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The K5OE 2-meter vertical mobile antenna design, detailed in this resource, employs a 3/8-wavelength vertical section complemented by four shortened radials, forming an off-center-fed vertical dipole. This configuration creates a self-contained lower half, enhancing efficiency compared to traditional 1/4-wave monopoles relying on vehicle bodies for a ground plane. The article specifies construction using PVC components, 10-gauge insulated wire for elements, and provides precise dimensions in both inches and centimeters for the 25-3/16" (64 cm) vertical and 7-3/16" (20 cm) radials. Performance data indicates an honest 3 dBi of gain at 6 feet elevation (2 dBi free-space), with a pattern favoring the horizon, suitable for Low Earth Orbit (LEO) satellite communications. At 20 feet high, the same antenna exhibits almost 6 dBi of gain, with a nominal 50 Ohm feedpoint impedance at 146.850 MHz. Tuning instructions involve trimming element lengths, with the author achieving a 1.2:1 SWR by pruning the mast to 24-3/4" and radials to 7". The resource highlights the antenna's effectiveness for mobile LEO satellite uplinks, particularly at low elevations, and its suitability for fixed, mobile, or portable operations. The flexible wire elements allow for easy folding, making it a practical choice for backpacking. The original design by K5OE was previously hosted on aol.com.

10 Meter WonderBar Antenna, present an SWR 1:1 over entire band, great DX, rotateable by hand, 8 ft long - build for about $20

The resource details the construction and performance of a dual-band 40/30 meter _Moxon_ antenna, evolving from an initial single-band 30-meter design that failed in a storm. It specifies materials such as four 10-meter fishing rods, galvanized iron TV antenna support pipes, 1mm diameter PVC-covered copper wire, and a piece of 75-ohm TV satellite cable for feedline. The document outlines the iterative design process, including initial resonance measurements of 9.9 MHz for 30 meters and subsequent recalculations to shift the center frequency by 300 kHz using _Moxon software_. Initial testing on a roof yielded SWR readings of 1.4:1 at 7.200 MHz and 1.5:1 at 10.280 MHz. After installation atop a 30-meter tower, the final SWR measurements were 1.1 at 7.130 MHz and 1.4 at 10.230 MHz, with a notable 30 dB front-to-back ratio on 40 meters. The 30-meter performance, while good, showed a front-to-back ratio of approximately 15 dB, suggesting a slightly high resonance. The antenna's placement on a 700-meter hill, with a significant ground drop in certain directions, is noted as a potential factor in its excellent DX performance, enabling daily contacts with the USA West Coast on 30 and 40 meters with 100 watts.

The ARRL ANTENNA Vol 5 COMPENDIUM features an article detailing two portable 6-meter antennas: a 2-element quad and a 3-element Yagi with telescoping elements. The 2-element quad exhibits a measured gain of **4.2 dB** over a dipole, while the 3-element Yagi achieves **5.8 dB** over a dipole. Both designs prioritize ease of construction and rapid assembly/disassembly for portable operations. Specific dimensions are provided for a 3-element 6-meter quad using #14 bare copper wire. The reflector element diameter is 6.2958 meters, the driven element 6.125 meters, and the director 5.8547 meters. Element spacing is 0.9398 meters between reflector and driven, and 1.1684 meters between driven and director. The SWR is under _1.26:1_ from 50 to 50.4 MHz, with a feed point impedance of 48.75 -j0.13 Ohms at 50.2 MHz, suitable for direct 50 Ohm coax feeding with a current _balun_.

A rotary trapped-dipole for 17 and 20 meters, as described by IZ7ATH, presents a practical solution for multi-band HF operation. The author, Talino, recounts his experience building this antenna for IK7ZCQ, detailing the evolution from an initial concept involving a grounded-driven element and gamma-match to a direct-fed, non-grounded design. His pragmatic approach, adapting available materials, is evident throughout the construction narrative, particularly with the use of eight tapered aluminum pipes for the driven element. Construction specifics include precise measurements for the aluminum tubing, with diameters ranging from 30 mm down to 16 mm, and a critical note on reducing tip thickness for weight optimization. The _traps_, initially a concern, are fabricated using 8 turns of RG58 coax on a 27 mm support, tuned to resonate at 18.1 MHz using a dip-meter. Talino emphasizes sealing the traps with RF glue and PVC tape to prevent water ingress, a crucial step for longevity. Field test results, conducted on a 10-meter pole in a clear garden environment, showed an SWR of 1.2:1 on 17 meters and 1.5:1 at 14.200 MHz. While SWR varied slightly when installed at Mario's QTH due to nearby objects, the antenna's performance remained commendable. The final half-dipole length is 46 cm for the 18 MHz tips, and the total weight is under 6 kg, with potential for further reduction.

Constructing a **2-meter** J-pole antenna from readily available copper plumbing components offers a robust and cost-effective solution for VHF operation. This design, dubbed the "Plumber's Delight," functions essentially as a half-wave dipole fed by 50-ohm coax via a **gamma match**. It incorporates a quarter-wave copper tubing support, which, when affixed to a metal mast or tower, enhances forward power in the direction of the radiating elements. The original configuration utilized a small ceramic trimmer capacitor for the gamma match, suitable for up to 10 watts. A subsequent modification replaced this with a 50 pF variable capacitor housed in a plastic enclosure, accommodating higher RF power and improving weather resistance. The antenna elements are secured using a copper "T" fitting, and an SO-239 connector mounts directly to this fitting. Performance includes gain away from the support mast, and tuning is straightforward by adjusting the gamma match capacitor for a 1:1 SWR. The total cost for materials, excluding the capacitor and coax, can be under $10.

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.

A PIC16F876 based, automatic 1.8 to 60 MHz Digital SWR/WATTmeter capable of displaying both the SWR and P.E.P.power values, with a bar graph on the second line tracking the instantaneous power.

W5ALT Indoor Vertical Antenna is a base loaded vertical antenna that can be tuned on almost all HF bands by adjusting a big coil. Operating a ham radio station from an apartment in Maracaibo, Venezuela, the author demonstrates effective communication with over 100 countries using a custom-built indoor vertical antenna. Addressing common misconceptions, the design uses a balanced approach with radials and a base-loaded vertical element made from affordable materials. The antenna fits discreetly indoors, covers 6 to 40 meter bands, and achieves acceptable SWR with an MFJ tuner. Despite limited space and typical apartment challenges, the setup enables reliable DX contacts, confirmed by numerous QSL cards, proving indoor antennas can perform well in constrained environments.

SWR and RF power meter for home usage, 8 different RF probes with different characteristics and power ranges by OK1DX

Details the construction of a portable _Moxon_ antenna optimized for the 2-meter band, utilizing readily available materials like 6.5 mm aluminum elements and a 15x15 mm TV boom. The design emphasizes ease of assembly and portability, making it suitable for field operations. Performance specifications derived from MMANA modeling indicate a forward gain of **6.3 dBi** and a front-to-back ratio of **15 dB**. Lateral attenuation is reported at 40 dB, with a minimum SWR of 1.1 at 144.300 MHz, confirming efficient operation within the target frequency segment. The antenna is lightweight at 500 grams, quickly assembled in approximately two hours, and disassembles into a compact 40x15x8 cm package. Direct feeding with RG-58 C/U or KX-15 coaxial cable via a BNC connector simplifies deployment.

The "Largest YU Moxon" document details the design and construction of a substantial multiband Moxon antenna, primarily for 80m, 40m, and 20m operation. It presents specific design parameters derived from NEC-based simulations, including a 4-element 80m Moxon with 37 dB F/B and 7.81 dBi gain on a 47m boom, a 4-element 40m Moxon with a bidirectional pattern, and a 6-element 20m Moxon optimized for specific side lobes. The resource provides precise element lengths and spacing in meters for each band, alongside measured SWR results across the 3.650-3.800 MHz, 7.000-7.100 MHz, and 14.000-14.350 MHz segments. The construction narrative outlines the challenges and solutions encountered by the YU team, including the use of trees for support, the creation of "ugly" air-choke baluns from RG-58 cable wound on plastic bottles for each band, and the meticulous process of attaching wires to a rope boom. It documents the physical dimensions of the vineyard site (47 x 38m) and the azimuth orientation (340 degrees) chosen for the antenna. The document is distinctively useful for its practical insights into large-scale antenna deployment in a field environment, offering real-world SWR measurements and anecdotal performance reports from CQWW contest operations. It includes numerous photographs illustrating the construction process, the team members, and the finished antenna structure, providing visual context to the technical details.

10 to 20 meters band log-periodic antenna project with SWR Plots, boom lenght and element spacing.

Inline RF Power & VSWR Meter. A DIY meter 0 to 30 Watt with Average and Peak. Circuit Description, Arduino Nano software code and part list to DIY your own Digital SWR Meter

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.

Over 75 years of engineering expertise underpins Bird Electronic's offerings in RF power measurement, critical for maintaining peak performance in amateur radio stations and professional communication systems. The company specializes in a range of test equipment, including wattmeters, SWR meters, and antenna analyzers, essential for optimizing antenna systems and ensuring efficient power transfer. Their product line extends to various RF components such as filters, cables, and connectors, all designed to meet stringent technical specifications for reliability and accuracy across diverse frequency bands. Bird Electronic's instruments, like the _Bird 43_ Thruline Wattmeter, are widely recognized for their robust construction and precise measurement capabilities, providing hams with confidence in their station's operational parameters. These tools enable accurate assessment of forward and reflected power, SWR, and modulation characteristics, which are vital for troubleshooting and maximizing radiated power. The company's commitment to innovation ensures that its products remain relevant for modern RF challenges, from HF through microwave applications, supporting both traditional analog and advanced digital modes.

Details a practical QRP wattmeter construction, leveraging a simplified SWR meter design by JA6HIC. The project focuses on a forward-only power measurement circuit, providing a functional instrument for RF power levels from milliwatts up to 5 watts. It maintains a 50-ohm input and output impedance, suitable for typical QRP transceivers and antenna systems. The resource includes the schematic for the "VSW" (Very Simple Wattmeter) and outlines a six-step alignment procedure. This calibration process involves using a known RF source up to 5W, setting full-scale deflection, and marking power increments. It also addresses minimizing frequency effects on readings with a 100pF trimmer capacitor, noting that measurement error is highest at the lower end of the scale. Construction notes mention using a piece of RG-213 coaxial cable for the inductance and coupler, with the wattmeter assembled in early 2003. The author provides an example measurement showing 0.8W into a dummy load and 1W into a 3-element beam.

BesserNet Reflectometer is a fun SWR calculator and simulator Java applet

Presents the design and construction of an automatically tuned 7-30 MHz mobile HF vertical antenna, originally published in _QEX / Communication Quarterly_ in 2003. The resource details a base-loaded vertical antenna system that mounts on a vehicle's roof, incorporating a variable inductor as its loading coil. A three-legged chariot, driven by a modified model airplane servo, travels inside the coil to adjust inductance. The control unit, featuring a _Basic Stamp microcontroller_ and SWR sensor, emulates a Kenwood AT-50 tuner for seamless integration with a _Kenwood TS-50_ transceiver, allowing automatic tuning across all ham bands from 40 to 10 meters. The project emphasizes practical application, providing a solution to the narrow-banded nature of mobile HF antennas and the inconvenience of manual band changes. It achieves a maximum SWR of 1.3:1 across its operating range. The mechanical design is thoroughly documented with detailed drawings, including a full-resolution GIF and AutoCAD R14 DWG files, illustrating components like the stainless steel whip, PVC coil tube, and the servo-driven chariot mechanism. Construction requires a lathe, but the author notes it can be accomplished with a hobby lathe, making it accessible to those with moderate mechanical skills.

This PDF document, authored by KT4QW in October 2004, details the construction and modeling of a dual-band, horizontally polarized hanging rectangular loop antenna for **10 and 17 meters**. The design, adapted from *The ARRL Handbook*, utilizes _NEC4WIN95_ software for scaling and optimization, targeting a 50 ohm feedpoint impedance. The resource includes a bill of materials, step-by-step construction instructions, and a discussion of the antenna's radiation characteristics. It presents NEC-generated elevation and azimuth patterns, comparing the loop's performance to a half-wave horizontal dipole at the same height and frequency. The 17-meter element is centered at 18.140 MHz for low SWR across the phone band, while the 10-meter element is centered at 28.500 MHz. Construction involves 14-gauge stranded copper wire and Schedule 40 PVC spreaders, with the total wire length calculated by the formula: Length in feet = 1005/MHz. The feedpoint impedance can be adjusted by modifying the rectangular aspect ratio. The document specifies hoisting the antenna to at least a half-wave above ground for testing. It notes that a balun was tested and found to have no measurable effect on SWR or radiation characteristics. A 2-meter scale model is presented to illustrate the physical design, and a "rotator" string is incorporated for directional adjustment up to 90 degrees.

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.

409 Shop is an Ham Radio and electronics online shop based on Hong Kong deliver worldwide. Ham Radio transceivers, batteries, swr meters, antennas and other ham radio accessories. Currently the shop seems to be out of business

Amateur radio accessories, power supplies, tvi filters, speakers, microphones, swr meters, preamplifiers, switches, cable and connectors,

The WN-1 is a precision RF Watt, SWR, and DC Meter to digitally monitor your amateur radio and emergency communications stations.

This technical note explores the application of **Moxon rectangle** antennas for WARC bands, specifically 17 and 12 meters, as compact directional alternatives to standard Yagis. It details three design approaches: a dual-band Moxon using open-sleeve coupling, a Moxon-Yagi combination, and a simplified 1.5 Moxon rectangle. The document provides specific dimensions in feet for aluminum tubing elements (0.75" and 0.5" diameter) for each configuration, along with projected free-space gain, front-to-back ratio, and feedpoint impedance (R+/-jX Ohms) across the respective band segments. Performance tables illustrate gain (dBi), front-to-back ratio (dB), and 50-Ohm VSWR for each design. The dual-band Moxon, despite its compact 7-foot boom, is not recommended due to extreme sensitivity to construction variations, leading to rapidly changing performance characteristics. The Moxon-Yagi combination, featuring a 17-meter Moxon and a 12-meter director-driver Yagi, is presented as a more practical and adjustable solution, offering stable performance with a 10-foot boom. NEC model descriptions are included for simulation in programs like EZNEC, NEC-Win Plus, AO, or NEC4WIN.

The N0KHQ Coax Square antenna, designed for 17 meters and built using RG-58 coaxial cable, presents an intriguing option for hams with limited space. L. B. Cebik, _W4RNL_, meticulously models and analyzes this array, clarifying its classification not as a modified Moxon, but as a distinct member of the "dual-coupled, 2-element, parasitic array" family. The design leverages the velocity factor of RG-58 (approximately 0.66-0.67) to achieve significantly shorter element lengths compared to full-size counterparts, resulting in a perimeter of 42 feet for the N0KHQ array versus 54 feet for a standard Moxon. _NEC_ modeling reveals the coax square's performance characteristics, including a forward gain of 5.6 dBi and a 23.7 dB front-to-back ratio on 18.118 MHz. While slightly less gain than a Moxon (6.0 dBi), its pattern exhibits Yagi-like nulls at 90 degrees, distinguishing it from the Moxon's wider beamwidth. The article also delves into the unique feedpoint considerations, explaining how the split braid and center conductor of the RG-58 driver effectively form a folded dipole, allowing for impedance transformation to achieve a good match for 50-Ohm cable. Despite its shortened elements, which inherently narrow the operating bandwidth, the coax square maintains satisfactory performance across the 17-meter band. The analysis emphasizes that while SWR curves are important, a holistic view of gain and pattern degradation across the band is crucial. This antenna is a viable solution for operators needing a compact, directional array, particularly for narrow bands like 17, 30, or 12 meters, where its high-Q performance is most effective.

Calculates precise dimensions for **Moxon rectangle** HF antennas, enabling hams to design antennas by inputting desired resonant frequency and wire diameter. This web-based tool, version 0.5, is a PHP front-end developed by W4/VP9KF, based on a public domain BASIC program originally authored by L. B. Cebik, W4RNL. It generates critical measurements for the driven element and reflector, ensuring proper spacing and element lengths for optimal performance. User feedback confirms the calculator's accuracy, with one user reporting resonance within 50 Hz of the design frequency for an 18 MHz antenna, eliminating the need for SWR adjustments. This contrasts with other online tools that resulted in significant frequency discrepancies. The tool's precision facilitates building **directional antennas** for specific bands, contributing to effective DXing and contesting operations.

An experimental antenna similar to the TAK spiral antenna was evaluated for SWR response over the frequency range of 7.0 to 7.3 MHz, or the 40-meter band.

Daiwa Industry, maker of power suppliers, coax cable and antenna switches, power meters, SWR meters, DC-DC converters

An easy to build single wire antenna for 160 and 80 meters with a better than 2 to 1 swr across the 80 meter band by K5GP

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.

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.

Presents the design and construction of the OK2FJ Bigatas, a portable, automatically tuned vertical antenna covering 80 through 10 meters. It details two distinct control systems: one utilizing BCD band data from Yaesu FT-857/897 transceivers, and another employing voltage level sensing for the Yaesu FT-817. The resource provides specific instructions for building the antenna's radiating element, loading coil with switchable taps, and the control circuitry, emphasizing the use of readily available components. The article outlines the physical construction of the antenna, including the use of duralumin tubes for the radiator and a PVC tube for the coil form. It specifies coil winding details, tap points, and the integration of radial wires for ground plane operation. The control electronics section provides schematics and component lists for both the BCD decoder (using a 74LS42 IC) and the voltage comparator (using an _LM3914_ bargraph driver), enabling rapid, automatic band switching without the minute-long tuning delays common in other systems. Crucially, the antenna achieves rapid band changes, with typical SWR values centered on common operating segments, such as **3.7 MHz** for 80m SSB. It also discusses modifications for CW operation on 80m and the trade-offs between antenna efficiency and full-range automatic tuning on higher HF bands, where manual adjustment of radiator length is suggested for optimal performance on 15m, 12m, and 10m. The resource includes construction photos and a discussion of cable requirements for reliable operation.

Based on the N2PK design, this swr meter use a stockton directional coupler

This project outlines the construction of a 3-element reversible quad antenna specifically designed for the 40-meter band. The materials required include pushup towers, pressure-treated posts, insulated wire, and various electrical components such as relays and a balun. The construction process is straightforward, beginning with the installation of the posts in a straight line, followed by the assembly of the antenna elements and their elevation to the desired height. The antenna's design allows for directional signal reception, making it ideal for operators looking to enhance their communication capabilities on the 40-meter band. The project includes detailed instructions on tuning the antenna for optimal performance, ensuring that operators can achieve the lowest SWR possible. Additionally, the design can be adapted for other bands by extrapolating dimensions, providing versatility for amateur radio enthusiasts. Overall, this reversible quad antenna project is suitable for both beginners and experienced operators, offering a practical solution for improving signal strength and directionality in 40-meter communications.

An easy to build single wire antenna for 160 and 80 meters with a better than 2 to 1 swr across the 80 meter band

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.

A 20-meter Moxon antenna design provides a compact directional solution for the 14 MHz band, achieving approximately **5.5 dBi** of forward gain and a front-to-back ratio exceeding 20 dB. This rectangular wire array, consisting of a driven element and a reflector, offers a smaller footprint than a traditional 2-element Yagi, making it suitable for space-constrained installations. Construction details focus on specific dimensions for the wire elements, fed with 50-ohm coaxial cable. The _Moxon rectangle_ inherently delivers wide bandwidth and a clean radiation pattern, simplifying tuning with a relatively low SWR across the entire 20-meter band. Its robust performance makes it a practical choice for both fixed stations with limited tower space and portable _DXing_ operations. The design's characteristics are particularly beneficial for contesting and long-haul communications on 20 meters.

Details the construction of a **17-meter Moxon Rectangle** antenna, specifically engineered for mounting on a mast beneath an existing beam. The design incorporates insulated wire calculations (0.95804 x generator length) to compensate for velocity factor differences, utilizing readily available materials such as crappie poles for elements, PVC for the boom and mast, and a Budwig HQ-1 dipole connector for the 50 Ohm coax feed. The project outlines a step-by-step assembly process, including mast construction from PVC T-connectors and pipe, element fabrication from crappie poles, and securing elements to prevent droop. Initial testing demonstrated an SWR of 1.3:1 on 17 meters, achieving a 5-8 signal report into Texas with 100 watts. Subsequent reinforcement and elevation of the antenna resulted in a 15 over 9 report from Florida. Comparative testing against an 88-foot center-fed Zepp antenna indicated superior performance, with the Moxon consistently outperforming the Zepp and receiving signals the Zepp could not. A notable DX contact with JA8NFV in Hokkaido, Japan, yielded a 5-9+ signal report both ways using 100 watts.

Constructing a high-gain, compact antenna for 2 meters often involves balancing theoretical performance with practical build challenges. WB8AHT recounts his journey in building a 6-element _Super Duper Moxon_ antenna for 144 MHz, inspired by designs from M0PXS and GW3YDX. He initially encountered discrepancies in published dimensions for the _HAARP Antenna_ and the _Super Moxon_, leading to on-air SWR issues and suboptimal performance. His methodical approach involved cross-referencing, direct communication with Phil Simpson (M0PXS), and iterative adjustments to element lengths based on observed results and a _SARK-110 Antenna Analyzer_ scan. After modifying the reflector/driven element and third director dimensions, the antenna achieved a respectable 1.35:1 SWR at 144.200 MHz. Field testing with 50 watts yielded contacts up to 500 miles, suggesting performance close to the 15 dBi gain predicted by _4NEC2_ software, despite its compact 40-inch boom. The article includes specific construction notes, such as tubing sizes (1/2-inch and 3/8-inch aluminum) and feedpoint spacing (50mm). The author's experience highlights the importance of real-world validation for antenna designs, even those with strong theoretical backing. He provides a table of tubing lengths for 6m, 4m, and 2m versions, along with his final, optimized dimensions, offering a practical blueprint for fellow hams interested in replicating or further experimenting with this high-performance, small-footprint VHF antenna.

Homebrewed SWR meters projects by G3TXQ

Are you experiencing very high SWR with the 10M Modification to Ameritron AL-811 amplifier ? This is a good forum topic to fix this problem.

The resource provides an in-depth analysis of the W6NL 40m _Moxon Yagi_ antenna, utilizing a NEC-2 model to simulate its performance. It details the antenna's design parameters, including element lengths and spacing, and explores critical operational aspects such as feedpoint impedance, SWR across the 40-meter band, and radiation patterns. The document systematically presents the model's setup and the methodology for evaluating the antenna's behavior in different environments, including free space and over real ground. Performance data derived from the NEC-2 model illustrates the antenna's forward gain, front-to-back ratio, and beamwidth. For instance, the model predicts a free-space gain of approximately **6.5 dBi** and a front-to-back ratio exceeding **20 dB** at resonance. Comparisons are drawn between free-space performance and operation at various heights above average ground, demonstrating the impact of ground proximity on take-off angle and overall efficiency. The analysis also touches upon the antenna's bandwidth characteristics, indicating its suitability for the entire 40-meter band with acceptable SWR.

Presents the construction and performance characteristics of a **2-meter vertical Moxon** antenna designed by WB5CXC. The antenna utilizes 1/2-inch PVC and #6 copper ground wire for its physical structure. Performance data includes measured front-to-back ratio using a local repeater, demonstrating significant signal attenuation when rotated. The resource provides **antenna pattern** plots, with blue tracing the design at 146 MHz and red indicating performance at 148 MHz. Gain and SWR plots are also included, alongside a detailed diagram of the antenna's physical layout. The design emphasizes a good front-to-back ratio, aligning with modeling predictions.

This array has been in use since 1989. The SWR from 3.5 to 3.9 is below 1.5:1. The F/R of the array is 20dB average and with some signals even better.

Operating a ZS6BKW antenna often involves understanding its lineage from the _G5RV_ design, with specific modifications by ZS6BKW to optimize performance on several bands. Through computational analysis and field measurements, the antenna's dimensions were refined to allow operation on 10, 12, 17, 20, and 40 meters without an antenna tuner. For 80, 30, and 15 meters, a tuner is necessary, though efficiency on 30 and 15 meters is noted as not particularly high. The physical configuration consists of two 13.755-meter radiating elements fed by a 12.20-meter section of 450-ohm ladder line. Tuning the antenna on the 20-meter band is critical, and any deviation in the ladder line's characteristic impedance necessitates recalculating the element lengths. The design is also referenced in the 12th edition of _Rothammel's Antennenbuch_, page 219. Proper common mode current suppression is crucial at the transition from ladder line to coaxial cable. This can be achieved with a common mode choke, such as several turns of coax wound into a coil or over a ferrite toroid like an Amidon T130. While a 1:1 balun is an option, it may introduce issues.

The document details the construction of a compact, two-element Quad antenna specifically designed for the 10, 12, and 15-meter HF bands, featuring a single feedline for all three bands. It provides specific dimensions for the driven element and reflector loops, along with boom length and spacing, emphasizing a **0.12 wavelength** spacing between elements. The design incorporates a gamma match for impedance transformation and uses PVC tubing for spreaders, aiming for a lightweight yet robust structure suitable for portable or restricted-space operations. Performance measurements indicate a forward gain of approximately **6 dBd** on 10 meters and a front-to-back ratio of _20 dB_ on 15 meters, demonstrating effective directivity and signal rejection. The antenna exhibits a VSWR below 1.5:1 across the target bands, achieved through careful tuning of the gamma match. This compact Quad offers a viable directional solution for HF DXing and contesting, particularly where full-size Yagis are impractical.

A delta loop antenna for 6 meters band with SWR diagram , construction plan and some pictures by IZ8EWD in Italian