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Demonstrates the construction of **magnetic loop antennas**, detailing both multi-turn and single-turn designs. It covers a 30-inch diameter multi-turn loop for 80 meters, based on a February 1996 QST article, and an octagon single-turn loop made from 15mm copper tube with a 4.8-meter circumference, operating from 7 MHz to 14 MHz. The document also presents a smaller 800mm diameter loop for 14 MHz to 28 MHz, emphasizing the importance of high-voltage tuning capacitors. Covers the design and construction of custom **butterfly capacitors** and piston capacitors, including a split stator capacitor with 140 pF capacitance and a 6000 Volt rating, and a butterfly capacitor with 5-65 pF and 7200 Volt rating. It explains why butterfly capacitors are preferred over split stator types for high power applications due to lower losses and direct series connection of rotors, reducing resistive losses from wiper contacts. Material recommendations include clear PVC for plates and brass or stainless steel for non-magnetic hardware. Addresses practical considerations such as feeding the loop with a shielded 1/5 Faraday loop made from RG213 or RG8 coax, achieving VSWR 1.1 across bands, and optimizing its placement 180° from the capacitor. It also discusses mechanical joint resistance, dissimilar metal oxidation prevention using Vaseline, and a simple method for determining radiation angle with a TL-light tube. The guide includes diagrams for rotor, stator, and end plate construction.

Constructing a 2-meter 5/4 wave antenna, N1HFX details a design fully enclosed within 3/4-inch PVC tubing, addressing the significant velocity factor of PVC which necessitates a 19% reduction in physical length. The design incorporates a specific matching system using 300-ohm TV twin lead to counteract the highly inductive impedance component inherent in a 5/4 wave radiator. Key components include #18 stranded insulated wire for the radiating element, RG58/U coax, a PL259 connector, and a hardwood dowel for internal support, all carefully dimensioned for optimal performance within the PVC housing. The article provides precise cutting lengths for the twin lead and #18 wire, with the overall assembly measuring 77 3/4 inches, reflecting an approximate velocity factor of 0.81. Tuning instructions emphasize taking SWR readings with the antenna assembly inside the PVC, adjusting the #18 wire and twin lead in small increments to achieve a low SWR across the 2-meter band. The prototype antenna achieved SWR readings below 1.2:1 across the entire band, and N1HFX suggests an estimated 6 dB gain when properly mounted, offering a cost-effective alternative to commercial antennas.

Details the construction of a J-vertical antenna specifically for the 10-meter band, offering a practical alternative to a _Slim Jim_ design for 28 MHz. The resource outlines the use of aluminum tubing for the half-wave vertical section and coaxial cable for the quarter-wave matching section, providing specific calculations for element lengths based on frequency and coaxial cable velocity factor. It contrasts the performance of the J-vertical with center-fed dipoles and end-fed verticals, noting superior results in previous comparisons. The article further presents a more recent iteration of the J-vertical, constructed using a fiberglass pole and insulated wire, with updated dimensions for 28.8 MHz. It includes practical advice on weatherproofing connections and securing the antenna for durability against adverse conditions, referencing the survival of an original _J Vertical_ during 110 MPH winds in 1987. The SWR performance is reported as 1.1:1 at 28.6 MHz, maintaining below 1.5:1 across 28.3 to 29 MHz.

Amateur radio operators often seek reliable equipment for various modes and bands, from QRP operations to high-power DXing. Historically, Ten-Tec has been a notable manufacturer in the amateur radio market, known for its range of products including HF and VHF transceivers, RF amplifiers, and antenna analyzers. Their product line also encompassed specialized items such as QRP transceivers and kits, catering to enthusiasts of low-power communication, and antenna tuners for impedance matching. The company's offerings included test equipment vital for shack setup and maintenance, like SWR meters and RF analyzers, which assist in optimizing antenna systems and ensuring efficient power transfer. Additionally, Ten-Tec provided various accessories and components, supporting both commercial products and homebrew projects. The brand was recognized for its _made in the USA_ manufacturing, appealing to operators who prioritize domestic production. While the website currently displays limited product information, it mentions upcoming items like the _MODEL 594 PHOENIX_ and the _Tune-A-Tenna_, indicating potential future product releases.

The RXO Unitenna, a vertical wideband antenna, offers operation across the 7-21 MHz spectrum, covering the 40, 30, 20, 17, and 15-meter amateur bands. This design focuses on achieving a low SWR across a broad frequency range, making it suitable for general HF operation without requiring an external antenna tuner for minor SWR variations. The antenna utilizes a unique loading coil and matching network to maintain efficient radiation characteristics across its operational bandwidth. Construction details within the PDF document include specific dimensions for the radiating element and the counterpoise system, which is critical for vertical antenna performance. The design incorporates readily available materials, simplifying the build process for radio amateurs. Performance graphs illustrate the SWR characteristics across the 7 MHz to 21 MHz range, demonstrating the antenna's wideband capabilities. The document also provides guidance on feedline connection and grounding considerations for optimal field deployment. This vertical antenna configuration is particularly useful for hams with limited space, offering a compact footprint compared to horizontal wire antennas.

Optimizing the impedance transformation and common-mode current suppression in antenna systems often involves selecting an appropriate balun. This project presents a **hybrid balun** design, combining characteristics of both voltage and current baluns to achieve superior performance, particularly when used with an antenna tuner. The design addresses issues like **common-mode current** on the feedline, which can distort the antenna's radiation pattern and introduce RFI in the shack. The construction details include winding techniques for the toroid core, component selection, and practical considerations for integration into an existing antenna system. Performance comparisons are drawn against conventional balun types, highlighting the hybrid balun's effectiveness across the HF bands. The resource provides insights into the current distribution and impedance matching properties, crucial for efficient power transfer and reduced SWR.

Determining the actual need for an antenna tuner often hinges on the specific antenna and feed line configuration in use. While many hams believe a tuner is always essential, its primary role is to present a 50-ohm impedance to the transceiver, not to "tune" the antenna itself. For instance, a resonant dipole fed with _coaxial cable_ at its design frequency typically requires no tuner, as the feed line impedance closely matches the radio's output. However, operating a non-resonant antenna, or using a resonant antenna on multiple bands, frequently necessitates a tuner to manage high Standing Wave Ratio (SWR) on the feed line. The article clarifies that a tuner placed at the transceiver only matches the radio to the feed line, not the antenna to the feed line. For maximum efficiency with a non-resonant antenna, an _automatic antenna tuner_ (ATU) or a remote tuner placed at the antenna feed point is often more effective, minimizing losses in the feed line. The discussion also touches on the practical implications of SWR, noting that modern transceivers often fold back power at high SWR, making a tuner a practical necessity to achieve full output power, even if the antenna itself is not perfectly matched.

Details the construction and optimization of antenna systems for amateur radio satellite operations, focusing on practical, homebrew solutions for VHF/UHF bands. It covers building _groundplane antennas_ from salvaged materials, recycling old beam antennas into new configurations like a 2-meter crossed yagi, and constructing a 10-meter horizontal delta loop. The resource also explains antenna matching techniques, including folded dipole driven elements and quarter-wave transformers, along with the importance of accurate SWR measurements and minimizing coax loss. Demonstrates how to achieve a **1:1 SWR** by carefully trimming elements and adjusting radial angles on groundplane antennas. It provides insights into selecting appropriate coax and connectors, highlighting the benefits of Belden 9913 for low loss and the proper installation of _N-connectors_. The article also addresses RFI mitigation from computer birdies and presents a design for a silent triac antenna control circuit, offering practical solutions for common satellite station challenges.

Demonstrates a **shunt-feed** matching technique for Hustler mobile HF antennas, specifically the MO-3 mast with RM series resonators, to achieve optimal **SWR** on the 40-meter and 20-meter bands. It details the construction of a loading coil using 20 turns of #12 solid wire, 1.25-inch ID, spread to 5 inches, and provides tap points: 8 turns for 40m and 4 turns for 20m, connecting one end to the feed point and the other to ground. The resource presents specific SWR results, noting a 1:1 match at 7.258 MHz on 40m and 14.275 MHz on 20m, with SWR remaining below 1.5:1 across significant portions of the General phone segments. It highlights a noticeable improvement in both transmit and receive performance compared to a straight antenna setup, emphasizing the practical application of this matching method for mobile installations, particularly on a fender-mounted ball mount.

Presents a practical design for a **crossed-dipole turnstile antenna** specifically engineered for 2-meter Amateur Radio Direction Finding (ARDF) events. The author, WB6RDV, details a robust, omnidirectional, horizontally-polarized antenna, addressing the international ARDF rules requiring such characteristics at a height of two to three meters above ground. This contrasts with the vertical polarization often used in Southern California, highlighting the design's adherence to specific event requirements. The electrical design employs a classic crossed-dipole with a 75-ohm phasing section, resulting in a slight impedance mismatch and an SWR of approximately 1.3:1 with a 50-ohm feedline. Construction utilizes readily available and inexpensive PVC plumbing components and 1/8-inch bronze welding rod for elements. The guide provides step-by-step instructions for mechanical assembly, including drilling element holes at precise 90-degree spacing and preparing the RG-179 matching section. WB6RDV shares insights from his own build experience, discussing the use of plated brass versus aluminum spacers for element attachment and the effectiveness of crimping as an alternative to soldering. The document also covers final assembly, including the integration of ferrite beads as a choke balun and options for weatherproofing and alternative mounting configurations, emphasizing the adaptability of the design for other VHF bands through scaling.

A 1.5-meter telescopic whip antenna project for the Yaesu FT-817 QRP transceiver is presented, offering a cost-effective alternative to commercial portable antennas like the Whip Miracle. The design incorporates a **toroidal matching unit** with a rotary switch for band selection and a toggle switch for fine-tuning the coil taps. This setup allows operators to achieve a low **Standing Wave Ratio (SWR)** across various HF bands, despite the inherent limitations of a physically short radiator on lower frequencies. The construction details include photographs of the completed unit, showcasing the compact enclosure and the integration with the FT-817. A simple schematic illustrates the coil tapping arrangement and the switching mechanism, guiding hams through the assembly process. The project emphasizes practical, portable operation for **QRP** enthusiasts, acknowledging that while performance on bands like 80m or 40m will be modest, it can still facilitate contacts under favorable conditions with skilled operation.

The article details the construction of a "bug-catcher" style HF mobile antenna, emphasizing its low cost and ease of tuning. It outlines the use of readily available materials such as PVC pipe, #14 house wire for loading and matching coils, and a _RadioShack_ replacement whip antenna. The design allows for operation across 20 through 6 meters, achieving an SWR of **1.5:1** or less on each band segment. The resource provides a comprehensive materials list, step-by-step assembly instructions, and photographs illustrating key construction phases. It explains how to create the coil forms, wind the coils, and secure them with epoxy putty. Crucially, the guide includes a table of suggested coil-tap positions and whip extensions for specific bands, such as 6 turns on the matching coil and 8 turns on the loading coil for 20 meters, facilitating initial tuning. Furthermore, the document discusses installation considerations, including grounding, and offers practical advice for tuning the antenna using an SWR meter. It highlights the antenna's broadband characteristics and its ability to collapse the whip for garage storage, making it a practical solution for mobile HF operation. The author, KM4IE, shares personal experiences with worldwide CW and phone contacts using this antenna.

Presents a catalog of **QRP** transceivers, antenna tuners, and related accessories for amateur radio operators. The product line includes the ZM-2 antenna tuner, designed for efficient impedance matching across HF bands, and the NW-series QRP transceivers, offering low-power CW operation. Additionally, the site details various ladder line insulators and specialized connectors, emphasizing robust construction for field deployment and home station use. Each product listing provides specifications, operational parameters, and pricing information. Compares the features of different **QRP transceiver** models, such as the NW-40 and NW-20, highlighting their respective band coverage and power output capabilities. The ZM-2 tuner's performance is detailed with typical SWR reduction figures for various antenna types, demonstrating its utility for portable and fixed stations. Customer testimonials and product images illustrate the practical application and build quality of EMTECH's offerings, providing insights into their durability and ease of integration into existing amateur radio setups.

Presents a detailed construction guide for a 2-element _Moxon rectangle_ antenna optimized for the 10-meter band, designed by L. B. Cebik, W4RNL (SK). This resource demonstrates how to build a compact beam antenna using readily available hardware store aluminum tubing, fitting within a 12-13 foot width. It highlights the antenna's performance characteristics, including a gain comparable to a 2-element Yagi (11+ dBi) and a front-to-back ratio exceeding 20 dB between 28.3 and 28.5 MHz, with an SWR below 2:1 across the entire band. The design emphasizes direct 50-ohm coax connection without a separate matching system, though a 1:1 choke _balun_ is recommended. The guide provides practical advice on element construction, corner fabrication using L-stock or radius-bent tubing, and the critical side-to-side length adjustment for SWR optimization. It details the feedpoint assembly using a chassis-mounting coax connector and discusses element-to-boom plate options, including spar varnished plywood or LE plastic. The author's experience with a test model on a 20-foot mast confirms stable feedpoint characteristics and excellent performance even at lower heights. The document also includes insights into the antenna's free-space azimuth patterns, noting a broad forward lobe and significant front-to-back rejection. It contrasts the Moxon with traditional Yagis, positioning it as an effective, home-buildable alternative for compact sites or _Field Day_ operations, particularly beneficial during periods of increased 10-meter activity.

Demonstrates the construction and performance of an updated ZS6BKW multiband dipole, a variant of the _G5RV_ antenna, specifically designed for HF operation. The article details a real-world installation using 13.5m copper wire elements and 12.2m of 450 Ohm ladder line, configured as a sloping inverted-V with the apex at 10m and ends at 4m above ground. It covers the critical aspect of impedance matching, incorporating an 8-turn choke balun at the feedline transition to RG-58U coax to mitigate RF common mode current. Measurements confirm favorable SWR readings below **1.3:1** on 7.1 MHz, 14.11 MHz, 18.06 MHz, and 24.8 MHz, indicating effective resonance across 40m, 20m, 17m, and 12m bands. The installation also shows usable SWR dips on 3.55 MHz (5:1), 29.02 MHz (2:1), and 50.84 MHz (3:1), extending its utility to 80m, 10m, and 6m with an antenna tuning unit. Initial on-air results report clear reception of stations over **5000km** away, validating its DX potential.

This resource details the construction and feeding of a vertical Moxon antenna specifically designed for the 20-meter band (14 MHz). It addresses the common issue of impedance variations at the feed point of vertical dipoles and Moxons, which typically requires the coax to exit at a specific angle (45-90 degrees) to maintain a good 50-ohm match. The presented solution involves opening the lower corner of the fed element and utilizing a transformer for impedance matching, simplifying installation and improving SWR. The alternative feeding method provides a stable match, eliminating the need for precise coax routing to achieve a low SWR. This design offers a practical improvement over conventional vertical Moxon feeding, making deployment significantly easier. The author, SM0DTK, confirms the efficacy of this setup, noting its fine performance and reduced installation complexity compared to traditional methods.

Presents the design and construction details for a VHF bicycle-mobile antenna, originally published in QST. The antenna utilizes a modified _Arrow J-Pole_ design, adapted for portable operation on a bicycle frame. Performance characteristics include a reported **1.5:1 SWR** across the 2-meter band, demonstrating effective impedance matching for typical handheld transceivers. Construction involves readily available materials, emphasizing lightweight components suitable for mobile deployment. The document provides a parts list and step-by-step assembly instructions, detailing the radiator and ground plane element lengths for optimal resonance at 146 MHz. Mechanical considerations for mounting on a bicycle are also addressed. The resource covers practical aspects of integrating the antenna with a bicycle, including cable routing and securing methods. It offers insights into achieving reliable VHF communications while operating in a mobile, low-power environment, making it relevant for field day activities or casual portable operation.

MoxGen is a **Windows** application designed to calculate dimensions and generate antenna model files for 50-ohm **Moxon Rectangle** antennas. Users input the desired design frequency in MHz and the wire size (AWG or diameter in inches/mm), and the software outputs the precise element lengths, spacing, and overall dimensions required for construction. It also creates a .maa file compatible with EZNEC, enabling further analysis and optimization of the antenna's performance characteristics. The software provides a visual representation of the Moxon rectangle, displaying key parameters such as gain, front-to-back ratio, and SWR at the design frequency. This allows radio amateurs to quickly assess the potential performance of their proposed antenna before physical construction. The generated EZNEC model facilitates detailed pattern analysis, impedance matching, and interaction with surrounding structures, proving useful for both initial design and fine-tuning.

This resource presents a detailed analysis of the W6NL 2-element 40-meter **Moxon Yagi** antenna, covering its design, construction, and measured performance characteristics. It outlines key specifications such as a free-space gain of 6 dBi, 11 dBi at 70 feet, and a direct 50-ohm feed. The document highlights the antenna's physical attributes, including 52-foot elements, a 27-foot boom, and a weight of 75 pounds, engineered to withstand 125 mph winds. Modeling was performed using **AO6** and K6STI software, with a focus on the unique functions of the transverse tip elements for Moxon coupling, physical balance, efficient capacitive loading, and reduced wind load. The presentation includes comparative data, showing the Moxon's superior front-to-back (F/B) ratio and wider bandwidth compared to traditional loaded Yagis. Performance graphs illustrate the SWR, gain, and F/B across the entire 40-meter band (7.0-7.3 MHz), comparing measured results against calculated values. Azimuth and elevation patterns demonstrate high F/B, with the antenna's pattern matching that of a full-size 3-element Yagi on a 30-foot boom. It also notes a gain difference of 1.5 dB down relative to a K3LR 4-element Yagi on a 50-foot boom, providing practical benchmarks for performance evaluation.

End-Fed Half-Wave Antennas (EFHWAs) are analyzed for their utility in portable QRP operations, emphasizing their simplicity, efficiency, and predictable radiation patterns compared to other portable antenna types. The discussion contrasts EFHWAs with vertical antennas, random length wires, and center-fed dipoles, highlighting the common pitfalls of each, such as ground system dependency for verticals and feedline issues for dipoles. The article details the electrical half-wavelength calculation using the formula L (Ft) = 468/F(MHz) and explains how EFHWAs can be resonant on harmonic frequencies, enabling multiband operation. Various deployment configurations are presented, including the inverted L, inverted Vee, sloping wire, and vertical setups, each with specific advantages for radiation angle and polarization. For instance, a vertical EFHWA offers a low angle of radiation suitable for DX contacts without requiring an extensive ground system. The resource also addresses the counterpoise requirements, suggesting a quarter-wavelength wire or connection to a metallic structure for decoupling. A schematic diagram for a simple parallel-tuned circuit tuner, based on the _Rainbow Bridge/Tuner_ design, is provided, detailing component values for 30 and 40 meters, including a 6 microhenry toroidal inductor and a 20-100 picofarad mica compression capacitor. The tuner's adjustment process for SWR matching is also outlined.

An antenna does not have to be resonant to work, as the primary reason for resonance is to eliminate the need for an impedance-matching device. A non-resonant wire dipole fed with open-wire line and an antenna tuner can function as an effective multiband antenna. Two wires are essential for powering an antenna, ideally with a balanced configuration like a dipole fed by parallel-wire line, though coaxial cable can be used with a 1:1 balun to mitigate RF feedback on the shield. Antenna gain is achieved by shaping and aiming RF energy, concentrating it in a particular direction, as seen in beam antennas or shaped radiation patterns of wire antennas. The function of an antenna tuner is to match the transceiver's 50 Ohm output to the antenna system's impedance, which can vary widely. Wire antennas do not always require center feeding; end-fed long wires or off-center-fed dipoles (Windom antennas) can be used, often requiring a counterpoise or radial system. Dipole antennas do not need to be perfectly horizontal; their legs can be bent, inclined, or even vertical, affecting feed point impedance. Vertical antennas shorter than a half wavelength necessitate a ground system, typically comprising radial wires, with more radials generally leading to greater efficiency. A 1:1 SWR indicates an impedance match but does not guarantee a good antenna, as an inefficient antenna with a poor ground system can still show a perfect SWR while wasting RF as heat. Always using the best feed line affordable is crucial for minimizing loss and maximizing RF signal delivery to and from the antenna.

Constructing a compact, two-band magnetic loop antenna for HF operation, especially from constrained locations like a balcony, presents unique challenges. OK1FOU's design, inspired by DJ3RW's 50 MHz loop, addresses these by employing an unusual side-fed configuration and placing the symmetric, two-section variable tuning capacitor at the bottom of the loop, directly connected to the coax shield. The article provides specific material recommendations, including two 1-meter wooden pales and about 3 meters of thick loudspeaker cable, noting the high current (60A at 100W) in the loop. Construction steps detail forming two turns with a 5 cm gap, using a GDO to pre-tune the open loop to a frequency slightly above the desired highest band, and then integrating the tuning and coupling capacitors. For 10/14 MHz, an open loop resonance of 16-17 MHz is suggested. Practical experience with the 10 MHz band from a third-floor balcony in Prague (JO70GC) shows a 1:1 SWR across most of the band without an external ATU. While DX traffic was modest due to the urban environment, QSO examples with RA6WF, LA6GIA, G0NXA, and LZ1QK on 10 MHz are provided, demonstrating its operational capability.

Demonstrates a practical modification to convert a standard G5RV antenna into a _160-RV_ for effective operation on the 160-meter band. This project addresses the challenge of achieving Top Band resonance with a common multi-band wire antenna, providing a solution for hams with limited space or resources for dedicated 160m antennas. The design utilizes a specific length of 450-ohm ladder line and a 1:1 current balun, acting as a matching section to bring the G5RV's impedance into a usable range for 1.8 MHz. The document includes a parts list, detailed construction steps, and tuning instructions, emphasizing the importance of precise measurements for the ladder line and coaxial cable sections. It also outlines the expected SWR characteristics and power handling capabilities, making it suitable for QRO operation up to 1.5 kW. The _AD1B_ design offers a straightforward approach for extending the utility of an existing G5RV.

This resource details the computer-optimized design of the _ZS6BKW_ multiband dipole, an evolution of the classic _G5RV_ antenna. It begins by referencing the original 1958 RSGB Bulletin article by Louis Varney G5RV, explaining the operational principles of the G5RV's flat-top and open-wire feedline on 20m and 40m, noting its impedance transformation characteristics for valve amplifiers of that era. The article then transitions to the rationale for optimizing the design for contemporary solid-state transceivers requiring a 50 Ohm match. The core of the project involves using computer modeling to determine optimal lengths for the flat-top and matching section, aiming for a VSWR of less than 2:1 on multiple HF bands. It discusses the process of calculating feedpoint impedance based on antenna length and frequency, referencing professional literature from Professor R.W.P. King at Harvard University. The analysis also considers the characteristic impedance (Z(O)) of the open-wire line, identifying a broad peak of adequate values between 275 and 400 Ohms. Specific design parameters for the improved ZS6BKW are presented, including a shorter flat-top and a longer matching section compared to the original G5RV, with a velocity factor of 0.85 for the 300 Ohm tape. The article confirms acceptable matches on 7, 14, 18, 24, and 28 MHz bands when erected horizontally at 13m, and also discusses performance in an inverted-V configuration, noting frequency shifts. The author, Brian Austin ZS6BKW, emphasizes the antenna's suitability for modern 50 Ohm coaxial cable without a balun.

The K0RWU 75-meter mobile antenna design features a 7.5-foot overall length, incorporating a 2.5-foot loading coil wound with #20 enamel wire on a 1/2-inch fiberglass rod, subsequently covered with 1/2-inch shrink tubing to increase diameter to 3/4 inch. This configuration achieved resonance at 3965 kHz with a 5-foot stainless steel whip. The antenna integrates a matching transformer, identified by larger turns near the PL259 connector, and is constructed using a modified Radio Shack CB antenna base. Construction involves drilling and epoxying a 1/2-inch fiberglass rod into a PL259 connector, feeding #20 enamel wire through the rod, and winding 17 turns of #18 matching coil wire between the PL259 sleeve and the center feed point. The main loading coil fills the 2.5-foot rod section. The design allows the antenna to bend for garage clearance and emphasizes maintaining a 50-ohm feed impedance to prevent vehicle electrical damage. The author also discusses experiences with a Yaesu ATAS-100 motorized antenna and a 10-meter antenna project, noting issues with auto couplers and the ATAS-100's performance on 17 meters. Future modifications considered include adding a small servo for band spreading and increasing the fiberglass rod length for a 3-foot loading coil to improve bandwidth. The antenna's sharp tuning, between 3960 kHz and 3970 kHz, necessitates careful adjustment of coil turns for optimal VSWR.

The ZS6BKW wire antenna, a variant of the G5RV, utilizes a specific 13m (42.6 ft) length of 450-ohm window line as its matching section, feeding a 28.5m (93.5 ft) flat-top element. This design aims for lower SWR on 40m, 20m, 17m, 12m, and 10m compared to a standard G5RV, often achieving SWR values below 1.5:1 on these bands without an antenna tuner. The feedpoint impedance transformation provided by the window line allows for direct connection to 50-ohm coax on multiple bands. F4FHH's experience involved constructing the ZS6BKW and evaluating its performance against an _OCF dipole_ (Off-Center Fed) on various HF frequencies. The article includes observations on SWR readings and operational effectiveness, highlighting the ZS6BKW's suitability for multi-band operation. The antenna's overall length, including the flat-top and window line, is approximately **41.5 meters** (136 feet), making it a significant wire antenna for fixed station use. Comparative analysis with the OCF dipole provided practical insights into the ZS6BKW's advantages and limitations, particularly concerning bandwidth and tuner requirements.

This resource details the conversion of an 80m elevated vertical antenna to include 160m operation, focusing on a relay-switched design over a trap-based approach. It presents specific feedpoint impedance values, such as **32 ohms** for 80m and **14 ohms** for 160m, and discusses the challenges of SWR drift encountered with the prior trap system during RTTY contesting. The article thoroughly explains the design choices for elevated radials, referencing _N6LF QEX data_ to debunk common myths regarding radial length and height, demonstrating that non-resonant radials can offer superior current uniformity. The construction section provides practical insights into building the vertical, including guying strategies, material selection from scrap pipe, and weatherproofing the relay assembly. It highlights the use of a common mode choke for the relay switching line, measuring approximately 5K ohms on both 160m and 80m, and details the L/C matching network's role in achieving a 50-ohm match at the end of a 300-foot RG-11 run. The author describes a precise VNA-based radial trimming procedure, achieving resonant values within a 3 KHz range. The content emphasizes the practical application of theoretical antenna principles, particularly concerning the interaction between the vertical element, cap hats, and the matching network. It offers a candid assessment of component selection, such as using junkbox parts and acknowledging the need for future upgrades to static drain resistors. The article serves as a comprehensive case study for advanced antenna builders tackling multi-band vertical designs.

Presents the mechanical and electrical specifications for a 5-element Yagi beam antenna designed for the 6-meter band. The resource details element lengths, spacing, and boom dimensions, specifically utilizing _EMT conduit_ for construction. It includes a diagram illustrating the element layout, a coaxial balun connection, and a reported SWR curve, providing a practical blueprint for hams to replicate the design. The design achieves a reported SWR of **1.1:1** at 50.125 MHz, indicating efficient impedance matching across the primary 6-meter DX window. The boom length is specified at 2.44 meters (8 feet), with element lengths ranging from 2.87 meters for the reflector to 2.59 meters for the director 3. This configuration suggests a gain figure typical for a 5-element Yagi, likely in the range of **9-10 dBi**, making it suitable for local and sporadic-E DX contacts.

A GSM1800 Moxon Square antenna project is presented, detailing its construction using three 1.5mm copper wire pieces for the reflector and dipole elements. The design inherently offers a 50-ohm feedpoint impedance, allowing direct connection to 50-ohm coax without complex matching networks like baluns or gamma matches, which are prone to high attenuation at 1.8 GHz if not precisely built. The resource includes a construction plan, expected **SWR plots**, and **radiation patterns** for the GSM 1800 band, specifically covering the 1710-1785 MHz transmit (red zone) and 1805-1880 MHz receive (blue zone) segments. The SWR remains below 2:1 across the entire GSM 1800 band, with the main lobe consistently achieving 5-6 dBi gain. While the radiation pattern shows some changes across the band, these primarily affect the back of the antenna, maintaining consistent forward gain. Practical considerations for high-frequency operation are emphasized, such as minimizing coax length (e.g., under 1 meter for RG-174) and selecting appropriate connectors like N, SMA, or BNC to mitigate significant attenuation. The article also discusses direct connection to the phone's RF PCB for minimal loss and notes observed signal strength variations with antenna orientation despite crossed polarization at cell sites.

A 20-meter vertical _Moxon_ antenna, designed for portable operation, is detailed with specific dimensions for its driven and reflector elements. The project outlines the construction process, including the use of PVC pipe for the frame and #14 AWG insulated wire for the elements. The antenna's compact size and directional characteristics make it suitable for field day operations or limited space environments, offering a gain of approximately 5.5 dBi and a front-to-back ratio of 20 dB. Testing revealed a 1.2:1 SWR at 14.250 MHz, demonstrating good impedance matching across the target frequency range. The _Moxon rectangle_ design provides a clean radiation pattern with minimal side lobes, which is advantageous for reducing QRM from unwanted directions. This build offers a practical solution for hams seeking a lightweight, easily deployable directional antenna for 20 meters without the complexity of a full-sized Yagi.

The ZS6BKW antenna, a popular multiband wire antenna, offers improved band matching compared to the traditional G5RV. This construction guide details the process, beginning with specific dimensions: 13.11 meters (43 feet) for the 450-ohm ladder line and initial dipole arm lengths of approximately 14.8 meters each. It emphasizes the critical role of an _antenna analyzer_ for accurate tuning, particularly for determining the velocity factor of the ladder line and achieving a 1:1 impedance match. The article outlines the materials required, including a 1:1 current balun, 450-ohm window line, wire for the dipole arms, and a 50-ohm non-inductive resistor for testing. It provides a step-by-step procedure for cutting the ladder line to its electrical half-wavelength, explaining how to calculate the velocity factor using measured and free-space frequencies. For instance, a measured 50-ohm impedance at 12.54 MHz with a calculated free-space half-wavelength frequency of 11.44 MHz yields a velocity factor of 0.91. Final adjustments involve hoisting the antenna to its operational height and fine-tuning the dipole arm lengths to achieve optimal SWR, specifically targeting 14.200 MHz. The _ZS6BKW_ design is noted for its performance on 80m, 40m, 20m, 10m, and 6m, though it is not optimized for 15m operation. The author, _VK4MDX_, shares practical tips for durable construction using stainless steel wire and cable clamps.

The resource details the construction of a 6-meter _Moxon_ antenna, presenting two distinct versions: one horizontally polarized for 50-51 MHz CW/SSB and another vertically polarized for 52-54 MHz FM. It specifies the use of 5/8 inch OD and 1/2 inch OD aluminum tubing, with 3/8 inch OD solid aluminum for corners, and provides a comprehensive material cutting schedule. The design aims for robust, portable construction, with all materials costing under $100. Detailed drawings and EZNEC models are referenced for precise dimensions and assembly, ensuring accurate element spacing and impedance matching. The EZNEC model for the H-POL version predicts a gain of **11 dBi** and a front-to-back ratio of **25 dB** at 50.5 MHz, while the V-POL version shows a gain of **6.7 dBi** and a front-to-back ratio of **36 dB** at 53 MHz. The article includes practical SWR measurement advice, noting the impact of coax length and loss on analyzer readings. Field tests during a tropical storm demonstrated the antenna's durability and performance, yielding numerous contacts across significant distances, including California, Colorado, and Texas, on SSB and PSK.

The **2M Moxon antenna** design presented operates at 144 MHz, providing a compact, directional solution for VHF communications. Construction involves aluminum tubing for the elements, with specific dimensions for the driven element and reflector to achieve optimal performance. The design aims for a good front-to-back ratio and a relatively low SWR across the 2-meter band, making it suitable for portable or fixed station use where directivity is beneficial. Element lengths are critical for proper resonance and pattern. The driven element measures approximately 38.5 inches, while the reflector is slightly longer at 40.5 inches. Spacing between the elements is 12 inches, forming the characteristic Moxon rectangle. This configuration yields a gain of about 5.5 dBi and a front-to-back ratio exceeding 20 dB, which is advantageous for reducing interference from unwanted directions. Feedpoint impedance is close to 50 ohms, allowing direct connection to coaxial cable without complex matching networks. The antenna's lightweight structure, typically under 2 pounds, facilitates easy deployment and rotation, making it a practical choice for field operations or as a compact home station antenna.

Demonstrates the design principles and performance characteristics of **corner reflector antennas**, emphasizing their high gain and directional properties. It covers critical design factors such as the corner angle and the spacing between the radiating dipole and the reflector vertex. The resource explains how reducing the corner angle increases gain but lowers feed impedance, making matching more challenging. Practical angles of 90 degrees or 60 degrees are discussed, with 90 degrees offering easier impedance matching despite slightly lower gain. Details key design considerations, including reflector side length exceeding two wavelengths and reflector width greater than one wavelength for a half-wave radiator. It specifies reflector construction using wire netting, sheet metal, or parallel metal spines spaced less than 0.1 wavelength. The article provides a table with general dimensions for UHF and VHF bands, noting typical impedance values of 50 to 75 ohms and expected SWR of 1.7:1 on the lower band edge. Adjustable radiator-to-vertex spacing is highlighted as crucial for final tuning.

A 50-ohm 10W resistor forms the core of this portable QRP antenna, designed by _K0EMT_ for convenient operation on 160m and 80m. The construction involves soldering the resistor to a BNC connector, with one lead to ground and the other to the center conductor, then insulating the assembly. This minimalist design aims to provide a highly portable solution for low-band QRP operations, acknowledging the inherent trade-offs between antenna size and efficiency. Testing with an antenna analyzer revealed low SWR on both 160m and 80m, with a Yaesu FT-817 confirming good matching. While 40m and 30m showed higher SWR, the primary focus remains on the lower bands. The author successfully tested the antenna with **2.5W CW** output, demonstrating its practical application for QRP field operations where ease of deployment is paramount, even if it means sacrificing some **gain** compared to full-sized antennas.

Accurately determining an antenna's feedpoint impedance is crucial for optimal performance, especially when experimenting with new designs or making adjustments. While SWR meters provide basic information, a full complex impedance measurement reveals the resistive and reactive components, which are essential for proper matching. Modern antenna analyzers, like the _Palstar ZM30_ or MFJ259B, simplify this task, but measurements taken through a transmission line require careful interpretation due to impedance transformation. This resource details a calibration method to precisely account for the effects of the feedline. It explains how a transmission line can significantly alter the measured impedance, illustrating this phenomenon with a Smith Chart example where an 80m antenna's [22 + j6] Ohms feedpoint impedance transforms to [82 + j45] Ohms after a 10m line. The guide demonstrates using a transmission line calculator applet, such as the one by W9CF, to reverse this transformation. It outlines the process of calibrating a specific length of RG174 coax, showing how an initial 26ft estimate was refined to **25.85ft** to accurately predict a known 22 Ohm load, significantly improving accuracy over uncalibrated results.

Optimizing the ZS6BKW antenna for full HF band coverage often requires specific modifications beyond its standard configuration. This resource details several enhancements, beginning with a simple series capacitor to improve 80m SWR, a technique W5DXP found effective for permanent installation due to its minimal impact on higher bands. Further improvements include a 10-inch parallel open stub for 10m resonance, shifting the frequency to 28.4 MHz with an SWR of approximately 1.8:1, a practical solution for Technician class operators. The document then explores a switchable matching section, adding or subtracting one foot of ladder line at the 1:1 choke-balun, which significantly impacts higher frequency bands and eliminates the need for a tuner on 17m. W5DXP's _AIM-4170D_ antenna analyzer measurements confirm these effects. More advanced modifications involve a parallel capacitor for further 80m SWR reduction, requiring remote switching for multi-band operation, and relay-switched parallel capacitors at specific points on the 450-ohm matching section to achieve low SWR on 60m, 30m, and 15m. These detailed steps, including _Smith chart_ analyses for the challenging bands, aim to transform the ZS6BKW into a truly all-HF-band antenna, reflecting W5DXP's practical experience in antenna tuning.

Demonstrates the construction of a 144 MHz turnstile antenna, detailing its design for omnidirectional, horizontally polarized VHF operation. The resource outlines the physical dimensions and materials required, including specific lengths for the radiating elements and the use of _RG-58_ coaxial cable for phasing. It covers the assembly process, emphasizing the critical spacing and connection points to achieve the desired radiation pattern and impedance matching for the _2-meter band_. The article presents measured _SWR_ performance across the 144-146 MHz segment, showing a low SWR of 1.2:1 at 144.5 MHz, which is suitable for general VHF use. It compares the turnstile's performance to a 9-element Yagi, noting the turnstile's advantage in providing consistent signal strength from all directions without requiring a rotator. Practical application for local FM simplex and repeater operations is implied, offering a simple yet effective antenna solution for fixed or portable stations.

The ZS6BKW multiband antenna, an optimized variant of the classic G5RV, features a 102-foot (31.1 m) horizontal span and a 39.1-foot ladder line matching section. This design, derived by G0GSF (formerly ZS6BKW) in the early 1980s using computer programs and _Smith charts_, aims for improved SWR across multiple HF bands compared to its predecessor. Construction details specify Wireman 554 ladder line and #14 AWG THHN copper wire for the radiators, with precise instructions for determining the velocity factor (VF) of the ladder line using an antenna analyzer or dip meter, ensuring accurate physical length for the matching section. The radiator length is electrically 1.35 wavelengths for the 20-meter band, requiring careful trimming during tuning. Field measurements with an _AIM-4170C_ analyzer by KI4PMI and NC4FB demonstrated good SWR curves and bandwidth on 6, 10, 12, 17, 20, and 40 meters. The antenna was deemed unusable on 15 and 30 meters due to very high SWR, but an LDG AT-100PRO autotuner successfully brought 6 and 80 meters into tune. Contacts were made on 80, 40, 20, and 17 meters, including a **17-meter** contact to Spain. EZNEC models for 80-6 meters are provided, along with an AutoEZ model by AC6LA, which predicted good SWR for 80-10 meters. W5DXP's modifications for an all-band HF ZS6BKW are also referenced.

Demonstrates the adaptation and construction of a 7-element DK7ZB Yagi antenna for the 4-meter band (70 MHz), utilizing components from a defunct 2-meter CUE DEE Yagi. The resource details the modifications made to the original DK7ZB design to fit the shorter CUE DEE boom length, specifically adjusting element lengths for 6mm rod elements while reusing existing mounting holes for the reflector and last director. It provides precise element lengths for the reflector, dipole (12mm aluminum tube), and five directors, along with a note on cutting elements for transport. The article includes a 4NEC2 simulation file for performance analysis and an SWR plot, confirming the antenna's electrical characteristics. It also specifies the calculation for the quarter-wavelength matching cable using SAT752F coaxial cable, resulting in a 909mm length. Practical application is shown with the finished antenna in operation at JO20XC, listing several activated Maidenhead squares such as JO56PA and JP40KS, validating its effectiveness for portable 70 MHz operations.

The ZS6BKW multi-band antenna, an optimized variant of the classic G5RV, is presented with detailed construction and tuning instructions. This resource outlines the antenna's design principles, which were developed by _Brian Austin (G0GSF)_ using computer programs and Smith charts to achieve optimal dimensions. It provides specific guidance on calculating and adjusting the lengths of the radiators (L1) and the matching ladder line (L2), emphasizing the critical role of velocity factor (VF) in achieving resonance. The article includes a step-by-step procedure for empirically determining the VF of ladder line using an antenna analyzer, ensuring accurate physical lengths for the matching section. It details the tuning process for the radiators, offering practical tips for incremental adjustments to achieve the best SWR curve. The resource presents SWR measurement results obtained with an _AIM-4170C_ analyzer across multiple bands, alongside predicted SWR graphs from an AutoEZ model. It confirms successful contacts on 80, 40, 20, and 17 meters, including a **17-meter DX contact** to Italy. EZNEC and AutoEZ models for the ZS6BKW antenna, covering 80 through 6 meters, are provided for download, allowing further analysis and customization. The document specifies component details, such as the use of Wireman 554 ladder line and #14 AWG THHN copper wire, and discusses the antenna's performance characteristics, noting high SWR on 15 and 30 meters but successful tuning on 6 and 80 meters with an external tuner.

The X80 multi-band HF vertical antenna, a commercial iteration of the Rybakov design, exhibits a physical length of 5.5 meters, or approximately 18 feet, and is constructed from aluminum tubing. It operates as a non-resonant vertical, requiring an external antenna tuner for impedance matching across its intended operating frequencies. The antenna's design incorporates a 1:4 UNUN at its base, facilitating a nominal 50-ohm feed point impedance for the coaxial cable. Performance observations indicate effective operation on 40 meters, 20 meters, 15 meters, and 10 meters, with reduced efficiency on 80 meters and 160 meters due to its relatively short electrical length for these lower bands. Comparative analysis with a G5RV dipole and a half-wave end-fed antenna reveals the X80 offers a lower take-off angle, beneficial for DX contacts, particularly on the higher HF bands. Field tests conducted with an Icom IC-706MKIIG transceiver and an LDG AT-100ProII autotuner demonstrate the X80's ability to achieve acceptable SWR across 80m through 10m. The antenna's compact footprint and ease of deployment make it suitable for restricted spaces or portable operations, though its performance on 80 meters is noted as a compromise compared to full-size resonant antennas.

Designing and constructing portable wire antennas for HF operations, this resource explores several configurations including the _foldback dipole_ for space-constrained setups and an inductively shortened dual-band dipole for 20m and 40m. It details the calculation of inductance for shortened elements, providing a Visual Basic 6.0 program screenshot that illustrates determining coil parameters like turns and length for a **25.5 uH** inductor. The document emphasizes practical considerations such as adjusting wire lengths for optimal SWR, noting that a dual-band dipole achieved SWR below 2:1 on both 20m and 40m, with careful adjustment bringing it under 1.5:1. Further, the resource describes a half-wave antenna matched with a coaxial stub, a method often referred to as the _Fuchskreis_ in German amateur radio circles, to transform the high feedpoint impedance to 50 Ohms. This monoband solution, for a 20m application, uses a stub length of **2.98m** (0.216 lambda multiplied by coax velocity factor) and a shorted stub of approximately 48cm. The coaxial stub design is highlighted for its resilience to ground proximity, allowing it to be rolled up or laid on the ground with minimal SWR impact, making it highly suitable for portable QRP operations.

End-Fed Half Wave matching unit project, based on a FT140-43 with SWR plot tests made using capacitor and without.

Presents construction details for Moxon antennas, specifically focusing on 10-meter and 17-meter band configurations. It covers practical aspects of building these directional wire arrays, including element spacing, feedpoint considerations, and material choices for optimal performance. The resource emphasizes homebrewing techniques suitable for amateur radio operators. Discusses the advantages of the Moxon rectangle design, such as its compact footprint compared to a full-size Yagi and its favorable front-to-back ratio. It provides insights into achieving proper impedance matching and structural integrity for portable or fixed installations. The content includes photographic examples of constructed antennas. Explains the iterative process of tuning and optimizing Moxon antennas for specific frequency segments within the 10m and 17m bands. It offers guidance on minimizing SWR and maximizing gain, drawing from real-world building experiences to assist constructors in replicating successful designs.

DK7ZB's fan dipole designs address the challenge of operating multiple HF bands with a single feedline, providing practical construction details for **multiband wire antennas**. The resource outlines specific lengths for half-dipoles across various band combinations, including 10-15-20m for classic bands and 12-17-30m for WARC bands. It emphasizes the importance of proper spacing between resonant elements to avoid impedance interaction and high SWR, a common issue when frequencies are too close. The article details the use of **current baluns** built with FT240-43 or FT140-43 cores, specifying turns and cable types for 1KW and 400-Watt power levels. It includes a correction table for adjusting dipole lengths based on frequency shifts, aiding in fine-tuning resonance. The 20+40m dipole is noted for its ability to operate on 15m with an ATU, demonstrating versatility.

Constructing a mobile HF antenna presents unique challenges, particularly when aiming for multiband operation and robust mechanical stability. This project details N1GY's adaptation of the KM4IE $20 antenna and the _Texas Bugcatcher_ design, focusing on practical build considerations and on-the-road performance. The author shares insights from winding coils on 2-inch PVC forms and integrating a salvaged fiberglass core from an old Hamstick-style antenna to enhance structural integrity, preventing potential failures from stress on PVC joints. N1GY's build includes a custom matching coil and a commercially sourced MFJ loading coil, carefully integrated into the design. The article provides specific tap settings for bands from 75 meters to 15 meters, achieving SWRs as low as **1.2:1** on 40 meters and **1.6:1** on 75 meters. Mechanical testing involved driving at speeds up to 70 MPH on Interstate routes, confirming the antenna's durability and the effectiveness of its PVC brace system. Further modifications address real-world usability, such as simplifying antenna removal for car washes. The ground strap was updated with a Power Pole connector, and the brace attachment to the luggage rack was converted to wing nuts, reducing removal time from 30 minutes to approximately _five minutes_. This iterative design process highlights practical solutions for mobile HF operation.

Presents the construction of a 2-meter **Skeleton Slot Yagi** stack, detailing the design process and practical considerations for VHF operation. The author shares insights from building and testing this antenna, emphasizing its performance characteristics for local and extended range contacts. The project outlines the specific dimensions and materials used, providing a clear path for other radio amateurs to replicate or adapt the design for their own stations. The resource covers the unique aspects of the Skeleton Slot radiator, explaining how its geometry contributes to gain and pattern control. It includes discussions on impedance matching and feedline considerations crucial for optimizing power transfer and minimizing SWR. The article draws on real-world testing, offering practical results that validate the theoretical design. This project serves as a valuable reference for those interested in custom VHF antenna solutions.

The TransWorld Antennas TW4040 The Adventurer Monobander™ is a portable HF antenna designed for rapid deployment in field operations, including **SOTA** and **POTA** activations. This manual details the antenna's assembly, tuning procedures, and operational guidelines for optimal performance on the 40-meter band. It outlines the specific components, such as the telescoping whip and base unit, required for proper setup. Instructions cover mast erection, radial wire deployment, and impedance matching to achieve a low **VSWR** across the designated frequency segment. The document also provides guidance on antenna orientation and environmental considerations for portable use. It specifies the antenna's power handling capabilities and physical dimensions when fully deployed and collapsed for transport.

The Superantennas MP-1 portable HF antenna is analyzed for its design and field performance, particularly its high-Q loading coil and 3/8-inch mounting. The review details the antenna's construction, including an 8-inch vertical section, a large-diameter loading coil tuned by a sleeve, and a 4-foot whip that disassembles into six rods for transport. Initial testing with the supplied 10-foot ribbon cable "ground plane" yielded poor SWR and RF hot conditions, indicating an inadequate ground system. Further experimentation with longer radials and resonant counterpoises for each band improved matching and eliminated RF hot issues, but introduced significant operational complexity. The author notes the difficulty in optimizing both counterpoise length and coil setting without an antenna analyzer, and the sensitivity of the MP-1 to counterpoise deployment. The review also discusses the recommendation to tune for maximum received signals rather than minimum SWR, often necessitating an external ATU due to the antenna's typical low impedance. The **MP-1**'s critical dependence on resonant counterpoises for effective operation, especially when elevated, is highlighted as a major drawback for portable use. The author ultimately sold the antenna, concluding that despite its sound technical design, its fussy nature and the need for extensive counterpoise management or an ATU detract from its portability and convenience compared to simpler, less expensive dipole solutions. The **Superantennas MP-1** is deemed a flawed portable antenna, requiring considerable effort to achieve its claimed performance.