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This project outlines a simple, cost-effective 40m band HF dipole antenna design, ideal for beginners. Constructed with insulated copper wire and a 1:1 balun, it offers a 50-ohm impedance, suitable for both 40m and 15m bands due to the harmonic relationship. Calculations account for a K factor, ensuring optimal length and performance. Antenna modeling with 4NEC2 confirms practical access to both bands, though real-world results may vary. Lightweight materials and straightforward assembly make it an accessible and versatile amateur radio solution.

This paper by Leif Asbrink (SM 5 BSZ) presents a practical approach to designing very high gain Yagi antennas, focusing on the "brute force" optimization method. The method, described in a previous article, ensures convergence independent of initial guesses. The paper provides detailed tables of element lengths and positions for Yagi antennas optimized for 144.1 MHz with a 50-ohm feed point impedance, aiming for minimal losses and high accuracy in comparisons.

145 MHz is the target frequency for this 2-meter Skeleton Slot Yagi Stack antenna project. The design focuses on feeding two stacked Yagi antennas using a skeleton slot radiator, which is a unique approach for VHF enthusiasts. The project details the construction process, including the loop tapered matching section for impedance matching, ensuring optimal performance. The use of specific components like the EH789 element holder and MB456 main mast bracket is highlighted, providing clarity on the assembly process. The construction utilizes 20x20 box aluminum bar for durability and precision. Key dimensions, such as the element length (ER-ED4) and main boom spacing (MM123), are meticulously outlined. This attention to detail aids in replicating the antenna design accurately. The downloadable PDF offers comprehensive instructions, making it accessible for amateur radio operators interested in VHF antenna construction. This project is particularly beneficial for those looking to optimize their 2-meter band operations. The inclusion of a skeleton slot radiator and loop tapered matching section demonstrates advanced techniques in antenna design, catering to both intermediate and advanced builders.

VE1ZAC's analysis details the performance of **MFJ927** and **SGC239** autotuners with portable HF vertical antennas, specifically comparing 31 ft and 43 ft configurations. The resource originated from challenges encountered during a Maritime QSO Party roving operation, necessitating a lightweight and easily deployable antenna system. Target bands for the contest included 80, 40, 20, 15, and 10 meters, with a maximum power handling of 100 W CW. The author utilized a 30-foot carbon fiber push-up pole to support a vertical wire element, noting its 2 lb weight and reliability. EZNEC modeling was employed to predict performance, showing favorable results for a 30-foot vertical with elevated radials, particularly on 40 and 20 meters. Feedpoint impedance measurements, taken with an AIM4170C, are presented for various HF bands, both with and without a 41-foot RG6 stub designed to reduce reactance on 80 and 20 meters. The stub significantly improved matching on these bands, easing the tuner's workload. Operational tests revealed issues with the MFJ927's reliability during contest setup, leading to reliance on the K3's internal tuner. The SGC239, tested post-contest, performed flawlessly. A detailed side-by-side comparison covers mechanical aspects, connection options, power bias, impedance range, board quality, and documentation. Modifications to the MFJ927, including a new aluminum case, white paint for heat reduction, and upgraded impedance-measuring resistors, are also described.

The Zeppelin antenna, a J-type design, is presented as a two-band HF dipole, offering independent operation on harmonically related frequencies. This resource details its electrical configuration, comprising a half-wave radiator end-fed by a quarter-wave matching section, and explores its historical evolution from early Zeppelin airship applications to modern amateur radio use. The article specifically examines how a Zepp antenna tuned to 28.4 MHz (10 meters) exhibits a harmonic relationship with 15.4 MHz (20 meters), noting a frequency ratio of approximately 1.84:1, which deviates from a perfect 2:1 due to factors like elevation, wire separation, velocity factor, and end-effect. Antenna modeling results, including SWR sweeps at 28.4 MHz (1.1 SWR) and 15.4 MHz (1.6 SWR), are provided through Graph 1 and Graph 2, illustrating the antenna's performance across these bands. Current distribution patterns for both the 28.4 MHz (second harmonic) and 15.4 MHz (first harmonic) operations are visually represented in Figure 2 and Figure 3, respectively. The author also includes a 4NEC2 model's "Symbol Conversion file" definitions and calculated #14 wire dimensions for achieving resonance at 28.4 MHz, with the antenna positioned at a height of 33 feet. The discussion further highlights the antenna's versatility, suggesting its potential as a single-band, center-fed, 15.4 MHz half-wave folded end dipole when fed at a specific low current point. This analysis provides practical insights into constructing and optimizing a multi-band Zepp antenna for HF operations, emphasizing its unique harmonic characteristics and physical compactness.

This project describes a high-performance EME antenna array consisting of two home-designed 9-element Yagis, each about 2.5 wavelengths long, combined into a 25-ohm system and matched to 100 ohms using 9/4λ sections of 50-ohm coax. The array supports rotatable polarity from 0° to 180°, allowing both horizontal and vertical polarization to optimize moonbounce performance under varying conditions. Despite operating for years without a balun—something another designer called “disastrous”—the system has delivered strong results, including copying very weak DX such as VK3KH at about -25 dB with only 120 W (around 2 kW ERP). The builder continues to refine the mechanics, having installed new gear motors and an upgraded follow-up control system in 2011.

This article explores the role of velocity factor (VF) in calculating stub lengths for VHF/UHF Baluns. It clarifies misconceptions about VF's relevance, distinguishing between coaxial cable interior fields and external stub fields. Practical examples, such as the Pawsey Stub and Coaxial Cable Balun, are analyzed alongside experimental findings. The results reveal that traditional VF adjustments are unnecessary for stubs with external fields but critical for internal coaxial applications. Historical and theoretical insights provide a comprehensive perspective for antenna enthusiasts and designers.

Twenty 1-watt carbon film resistors are configured in parallel to construct a 50-ohm **dummy load** for amateur radio applications. The design incorporates a heatsink for thermal dissipation and an **SO-239 connector** for RF input, making it suitable for QRP operations. This budget-friendly project details component selection, soldering techniques, and mounting procedures, achieving a continuous power rating of 10 watts and intermittent handling of up to 100 watts across HF and VHF frequency ranges. The resource provides a step-by-step guide for assembly. This construction offers an economical solution for essential shack tasks such as antenna tuning, transmitter testing, and SWR meter calibration without radiating an RF signal. The utilization of readily available components significantly reduces the overall build cost compared to commercial alternatives, providing radio amateurs with a functional and reliable test accessory. While specific VSWR measurements are not provided, the design prioritizes practical utility for low-power transceiver diagnostics and general RF experimentation.

Presents an online retail platform for amateur radio operators, showcasing a diverse inventory of equipment and accessories. The site lists popular transceivers such as the _Icom IC-7300_ and _Icom IC-7610_, alongside various antenna solutions including base, HT, mobile, and end-fed designs. Operators can find coaxial cable, including bulk options and products from "The Wire Man," essential for shack setup. The platform also stocks crimping and stripping tools, adapters, and power supplies, crucial for station maintenance and construction. Test equipment like _RigExpert Analyzers_ and accessories such as Daiwa meters and _West Mountain Radio_ Power Poles are available. Additionally, the site offers software from _Ham Radio Deluxe_ and _RT Systems_, catering to logging and radio programming needs. Shipping policies include free shipping on C.Crane Radios and most orders over $100.00 within the lower 48 states, providing clear purchasing incentives.

This resource presents a non-rigorous evaluation of the front-to-back (F/B) ratio of short Beverage antennas, specifically designed for low-band operation on frequencies such as 160, 80, 40, and 30 meters. The author, VE1ZAC, details the methodology used to measure the F/B ratio, which involves using a Millen Grid Dip Oscillator as a portable signal source. Measurements were taken by switching the antenna direction and recording S Meter and preamp readings to derive gain numbers. The document discusses the challenges faced in achieving accurate measurements and the assumptions made during the process, such as the calibration of S Meter units at 6 dB. This evaluation is particularly relevant for amateur radio operators interested in antenna performance on low bands.

This article describes a DIY RF field strength meter project inspired by VK3YE's "The Squeakie" design. The device, built around a 555 timer IC and a 1N4148 diode, converts RF signal strength into audible tones with proportional pitch. The author enhanced the original design by adding volume control, LED indication, and digital readout capabilities using an Arduino Nano and LCD display. The completed project functions as a versatile RF detection tool, suitable for antenna testing and fox hunting, while offering multiple output methods: audio, visual, and digital measurement display.

A 5/8-wavelength vertical antenna for 2-meter FM operation is detailed, focusing on eliminating loading coils by utilizing a series inductor to cancel capacitive reactance at the feed point, thereby presenting a 50-ohm impedance match. The design illustrates three basic configurations, including a method employing a short-circuited coaxial stub for inductance, as implemented by K4LPQ. An alternative design is presented where the center conductor of the stub is extended one-quarter wavelength, creating a signal-frequency short and allowing for an insulated wire stub to develop the required series inductance. The article provides electrical theory and mechanical considerations for building the antenna, emphasizing the adjustment of stub length for proper impedance matching. This technical documentation is intended for amateur radio operators interested in homebrewing VHF antennas, offering practical insights into impedance matching techniques for vertical radiators.

This page offers an online tool to calculate the dimensions for a quarter wave antenna based on a specified frequency. It helps hams design antennas for optimal reception and transmission properties, using 1/4 wavelength elements. The calculator ensures a matching impedance of 50 Ohm without the need for additional components. The page is useful for amateur radio operators looking to build efficient antennas for their radio communication setup.

Demonstrates the design and modeling of a **160m** vertical antenna, dubbed the "WindoVert," specifically for urban amateur radio operators with limited space. The resource covers the theoretical underpinnings of antenna height and radiation patterns, using EZNEC software to analyze current distribution and 3D radiation patterns for various configurations, including a Marconi-style "T" antenna. It details the integration of existing antenna components, such as a Carolina Windom balun and line isolator, into the new vertical setup, and the practical measurement of feedpoint impedance using an antenna analyzer. The article further explores the challenges of achieving low-angle radiation on Top Band, emphasizing the critical role of radial systems and mitigating ground loss. Author VE1ZAC presents EZNEC models illustrating the impact of lumped components and discusses the practical considerations of resonant frequency adjustment and impedance matching for **QRP** operation. The text details the calculation of required loading coil inductance and capacitance, and shares field results, including successful DX contacts on 160m and unexpected excellent performance on 30m.

The article describes adding lightning protection to Beverage antennas, which are long wires susceptible to lightning strikes. The author reviews common lightning protection circuits and discusses their components. They then detail their design based on existing methods, highlighting choices for components and reasoning behind them. Finally, the author presents the completed design and its implementation on their Beverage antennas.

SAT filters ensure effective full-duplex satellite QSOs by mitigating interference between 145 MHz uplink and 435 MHz downlink signals. Custom coaxial and SMD-based filters address transmitter harmonic interference and improve receiver isolation, achieving over 70 dB suppression in the undesired band. Designed for simplicity, these filters maintain optimal VSWR and are housed in shielded brass enclosures. Practical implementations with Yagi antennas demonstrate compatibility with SDR systems, enabling seamless communication even in challenging satellite conditions, such as low-elevation passes and DX pile-ups.

The UHF J-Pole antenna described here utilizes an aluminum angle bar and 4mm galvanized threaded rod for its construction, with dimensions based on a previously published design. Assembly involves drilling the angle bar, securing threaded rod sections with nuts, and connecting the coaxial cable via cable lugs, ensuring the braid connects to the shorter element. ROS adjustment is achieved by manipulating nuts approximately **30mm** from the angle bar, allowing for fine-tuning of the impedance match. Once optimal tuning is established, _super glue_ is applied to seal the coaxial cable ends and protect the threaded rod cuts from corrosion, enhancing durability. This project emphasizes rapid realization with common hardware, providing a practical solution for radio amateurs seeking a simple yet effective antenna for the 70cm band.

Demonstrates the construction of an active loop converter specifically designed for the Low Frequency (LF) bands, addressing common localized noise interference in LF reception. The design integrates a sharply tuned circuit and a tuned loop antenna, utilizing the loop as the sole tuned inductive element. By applying positive feedback, the converter significantly increases the loop's effective Q, achieving factors between 1000 and 2000, which sharpens tuning and reduces noise. The circuit employs an _NE602_ mixer stage, feeding its output to an HF receiver, with a crystal-locked local oscillator at 4 MHz. A 20-turn, 0.8-meter square loop antenna with 500 uH inductance is detailed, connected via 2 meters of figure 8 flex cable. The converter offers three selectable frequency bands: 195-490 kHz, 150-220 kHz (including the New Zealand amateur band), and 128-160 kHz (covering the European amateur band). Performance measurements indicate an effective 3dB bandwidth of approximately 100 to 200 hertz at 200 kHz. The article provides insights into component selection, including an _LF353_ op-amp and a trifilar wound transformer on a ferrite core. Sensitivity figures are presented, showing 7.5 uV of converted output per 1 uV/meter signal strength into a 50-ohm load, or 37.5 uV into an _FRG7_ receiver, highlighting its capability to extract weak signals from noise.

Demonstrates the construction of a portable 2-meter repeater system utilizing a **Yaesu DR-1X** transceiver, configured for both analog FM and C4FM digital voice operation. The design emphasizes portability, robustness, and effective thermal management, incorporating a "wind tunnel" airflow system with a fan to maintain transmit module temperatures at 38 degrees Celsius during continuous operation. The system integrates a diplexer, control head, and is housed in a compact, lightweight case weighing under 8kg, designed for single-person deployment. Covers practical considerations for field deployment, including power sources, antenna types, and the overall system architecture for public service events and emergency preparedness. The resource details the modular "wrap around" construction, showing how components like thermal switches for fan control and Anderson Powerpole connectors are integrated. It highlights the system's ability to provide reliable communications support for club activities and emergency communications.

This presentation explores the practice of QRP (low-power) amateur radio operation in outdoor settings. It guides operators to identify their specific objectives for portable operations, which inform equipment and antenna choices. The discussion covers considerations including portability, operating modes, power requirements, and weather resistance. Various antenna designs are examined, from vertical configurations to dipoles and end-fed options, with emphasis on deployment practicality in public spaces. The presentation concludes with practical advice on selecting operating locations, RF safety, and resources for equipment and community support for QRP enthusiasts.

SO2R Focus Control and SO2R FC Server are freeware VB6-based tools enabling remote or local control of modern SO2R controllers (supporting OTRSP and MK2R protocols) outside contest logging sessions. The client (SO2R Focus Control) manages serial-connected controllers and can interface remotely via LAN or internet using the optional SO2R FC Server, which supports up to two concurrent clients. Key features include AUX port control with customizable labels, interlock options, AES-256 encrypted network communication, and compatibility from Windows XP through Windows 11. Designed for operators needing flexible station control—especially for remote antenna switching—both programs install cleanly via NSIS and uninstall completely.

The 4m Slim Jim antenna project provides a construction guide for a low-cost, high-performance aerial designed specifically for the 70 MHz FM band. This design achieves a 1:1 SWR across the 4m FM band with straightforward adjustment of the feed point, utilizing RG-58 coax. Its low angle of radiation contributes to effective signal propagation. Construction involves using plastic knitting needles as spreaders and a telescopic fishing pole for support, with components secured using two-part epoxy. Annealed bare single-core copper wire forms the radiating element. The setup process includes raising the antenna at least 3 meters above ground for tuning, adjusting the RG-58 feed point for optimal SWR, and then soldering connections. Waterproofing is achieved with yacht varnish. The design emphasizes low wind resistance for durability, making it suitable for exposed outdoor installations. A PDF construction diagram is available to supplement the written instructions.

The W6PQL 23cm Beacon Project describes a **1296 MHz** beacon designed for microwave propagation studies and equipment testing, capable of 30 watts output. It utilizes a PIC 16F628A microcontroller to generate CW and FSK keying for a crystal oscillator, followed by a series of frequency doublers and triplers to reach the target frequency. The final power amplification stage employs a Mitsubishi M57762 module, providing a robust 10-watt RF output. The design emphasizes stability and reliability for continuous operation, with the microcontroller code, written in assembly, provided for customization of the beacon's callsign and message. Originally located in CM97am and aimed at 140 true, the beacon used four 4-foot Yagis stacked vertically for a total ERP of 3kW. The article includes schematics, parts lists, and construction notes to guide builders, along with antenna pattern measurements. Although the beacon itself is no longer in service as of August 2010, the detailed documentation remains a valuable reference for amateur radio operators interested in building similar **microwave** projects or understanding beacon operation.

The Anytone AT-D878UVII Plus, a dual-band transceiver, supports both Analog and DMR modes, providing versatile communication options for amateur radio operators. This model is complemented by the Anytone AT-6666 Pro, which delivers a substantial 80W output, catering to users requiring higher power for their radio operations. For mobile and off-road applications, RadioSmart Solutions features a 4x4 Mobile Radio Package Deal, which includes the RTS DV-2135s Mobile Two-Way Radio. This package is specifically designed for reliable communication in challenging environments, often encountered during off-road adventures. An _RSS Rugged Off-Road Antenna_ is also available, engineered to withstand harsh conditions and ensure robust performance. The product range addresses the needs of individuals seeking durable and functional communication solutions for both general amateur radio use and specialized mobile deployments.

This document details the construction of a portable 6-meter 4-element quad antenna designed for VHF and Field Day events. The antenna features a 10-foot boom and utilizes #12 bare wire elements. Spreader arms are fashioned from 3/8" OD x 48" fiberglass electric fence posts, with a modification required to reduce the ends to 0.370" OD for proper fit. Alternatively, 3/8" OD fiberglass tubing with a pre-reduced diameter can be used. Synthetic lumber hubs allow for post-assembly adjustments by sliding and locking along the boom. Spreader clamps, made from 3/4" OD fiberglass rod, incorporate 3/8" x 1" deep spreader holes and 1/8" element holes with countersunk edges. These clamps are drilled and tapped for 8-32 nylon thumbscrews, using both taper and bottoming taps for secure wire fastening. The antenna is designed for field assembly in approximately 10 minutes, requiring only a wrench for mast attachment. It offers comparable gain to a 6-element OWA Yagi while being smaller and lighter.

Navigating the complex legal landscape of **antenna zoning** and permit acquisition for amateur radio installations requires specific knowledge, which Fred Hopengarten, K1VR, provides through his resource. This content details the essential steps and regulatory considerations for securing permits for antenna support systems and towers. It focuses on the legal and procedural requirements, offering insights into local ordinances and federal regulations that impact amateur radio operators seeking to erect significant antenna structures. K1VR's expertise as a telecommunications lawyer is evident in the practical advice offered, drawing from real-world scenarios in permit applications. The resource equips hams and their legal counsel with the information needed to successfully navigate municipal zoning boards and secure necessary approvals, contrasting with purely technical antenna design guides by emphasizing the administrative and legal pathways to installation.

Radio classifieds, technical articles, reviews and antenna designs for CB and Amateur bands.

A common mode choke/balun, essential for mitigating common mode current on antenna feedlines, is detailed in this construction and measurement guide. It utilizes eight Fair-Rite #2643167851 Mix 43 ferrites housed within a Hammond 1598JSGYPBK plastic case, with RG-8X coax cable forming the windings. The document references design principles from Ian White, GM3SEK's article on cost-effective ferrite chokes. Specific construction details include the layout of three coils to minimize inter-coil coupling and methods for securing the ferrites with foam tape. The resource presents comprehensive measured data, including isolation impedance (magnitude, real, and imaginary components), Q factor, inductance, and phase angle across various frequencies. It also covers the choke/balun's coax frequency response and return loss characteristics. Techniques for measuring choking impedance are thoroughly explained, focusing on S21 transmission measurements with a Vector Network Analyzer (VNA) and testing ferrite beads in both S11 and S21 modes. The guide describes a practical setup using an aluminum sheet or baking foil for measurements and outlines the calculation of series impedance from attenuation in a 50-ohm system. Additionally, it details a method for determining the balun's equivalent L and C around resonance by adding a parallel capacitor.