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DL7JV shares his practical experience building and testing capacitive antennas, initially skeptical of their performance compared to magnetic loops and mono-band dipoles. His interest was piqued after hearing a Spanish station running 100 Watts on 80 meters with a 1-meter Micro Vert, making DX contacts into PY and UA0, despite the antenna being only 4 meters high in a garden. This prompted DL7JV to investigate further, consulting resources from DL7PE and DL7AHW, the latter providing DOS programs like "Mitspule.exe" and "Spulenprg.zip" for calculating antenna dimensions and coil conversions. The article outlines the construction of two prototype antennas: one for 7.050 MHz using a 75mm PVC pipe and another for 3.550 MHz with a 110mm PVC pipe. Both designs feature aluminum foil condensers and coils wound from 1mm² H07V-K wire. DL7JV provides specific measurements for the condenser capacitance, surface area, diameter, height, coil inductance, turns, and wire length for both 40m and 80m versions, along with RG58 feedline lengths. Initial reception tests for the 7 MHz antenna, placed indoors, yielded impressive S9+5 signals from a German station compared to an S8 from a 42-meter roof-mounted loop, even hearing a Japanese station. Transmission attempts on April 4, 2004, despite moderate solar storm conditions, resulted in successful QSOs on 7 MHz with EA5OT (579/559) and on 3.5 MHz with YT1NT (579/559) and G4KKI (579/559) using 100 Watts. DL7JV notes the antenna's sensitivity to coordination and feedline layout, suggesting a modification from DL7AXO involving a 500pF fixed capacitor and coil tap for improved SWR stability. He concludes that while the capacitive antenna is space-saving and performs well for reception and 100W transmission indoors, its transmit performance doesn't yet match larger antennas, with further outdoor field tests planned. DL7JV also intends to build a 1.8 MHz version.

Paul McMahon presents a compact VSWR meter designed for QRP portable use, ideal for SOTA operations with rigs like the FT817. The device, constructed from readily available components, employs a simple resistive bridge for wideband performance from 1.8MHz to 52MHz, with diminishing accuracy at higher frequencies. Key features include no need for external power, simple calibration, and operation with low power levels. The design, detailed with parts lists, schematics, and construction guidelines, ensures a 2:1 worst-case VSWR to protect transceivers during antenna matching. Calibration points are set for accurate VSWR readings at various loads.

This device was designed as an SWR and power meter for Radio Amateurs. In addition to SWR, it measures forward and backwards power, therefore can also be used as a wattmeter. With a large measuring range from 1 to 1000 watts, it is suitable for use from QRP to QRO

Analysis, design and construction of a simple & useful SWR meter from yesteryear! Schematic diagram, pictures and instructions to build a Monimatch style SWR Meter

Steve Nichols, G0KYA, presents a practical examination of ground systems for vertical antennas, drawing heavily on the empirical research of Rudy Severns, N6LF. He explains that a robust radial field is crucial for ground-dependent verticals, effectively replacing the antenna's "missing half" and mitigating severe RF absorption in lossy soil. Nichols clarifies that surface radials do not strictly require a quarter-wavelength; instead, deploying a minimum of 16 to 32 shorter wires often yields superior results compared to fewer, longer ones. The presentation also addresses the common SWR paradox: a poor ground might show a perfect 1:1 match, but adding radials, while potentially raising the SWR to around 1.4:1, significantly improves true radiation efficiency. Nichols defines counterpoises as elevated wire networks that substitute for earth connections, offering solutions for limited-space installations, such as the **Folded Counterpoise (FCP)** for 160 meters. This resource provides actionable engineering data for optimizing vertical antenna performance.

Building an End-Fed Half-Wave (EFHW) antenna from a kit, as detailed by Frank Bontenbal, PA2DKW, with process photos by Bob Inderbitzen, NQ1R, offers a practical approach for hams. This specific kit, a collaboration between ARRL and HF Kits, targets 10, 15, 20, and 40 meters, making it a versatile option for HF operations. Unlike a center-fed dipole, the EFHW is a half-wavelength antenna fed at one end, which simplifies deployment, particularly for portable use. The construction guide meticulously outlines the assembly of the 49:1 impedance matching network, crucial for transforming the antenna's high impedance (around 2,500 Ohms) to a transceiver-friendly 50 Ohms. Steps include preparing the enclosure by drilling holes for the coaxial connector and antenna connections, followed by the precise winding of enameled copper wire onto a toroid to create the transformer. The guide emphasizes careful insulation removal and soldering for reliable connections. Final assembly involves integrating a 100 pF capacitor for higher band compensation, soldering the transformer's primary and secondary sides, and conducting SWR tests with a 2K7 resistor or a half-wavelength wire. The document also provides examples of wire lengths for different bands, such as 16 feet for 10 meters or 66 feet for 40 meters, demonstrating the transformer's adaptability for various half-wavelength configurations.

This antenna is reported as being lower noise than conventional yagis and had a very low SWR for 500 KHz.

Reflected power and VSWR Metering on Yaesu FT-817, and proper interpretation of real values. The power output meter it is a relative indicator of the antenna match that the radio is experiencing. Reference table and how correctly read the values of the Yaesu internal meter.

QuickSmith provides an online _Smith chart_ for impedance matching, enabling users to drag virtual components onto a ladder network and observe dynamic trace movement. The tool displays live readouts for critical parameters such as VSWR, return loss, insertion loss, loaded Q, and bandwidth. It facilitates auto-matching to **50 ohms** with various network choices and supports _Touchstone_ file import, allowing _NanoVNA_ measurements to be plotted directly for analysis. Beyond basic matching, QuickSmith includes features for frequency and component sweeps, generating S11 and S21 response graphs. It also supports amplifier design, incorporating stability, gain, and noise circles, alongside microstrip and coax synthesis capabilities. The platform offers shareable links, worked examples, and guided tours, making it a practical resource for hams learning about RF circuit analysis and antenna optimization.

A 10-meter half-wave vertical antenna, designed by Thomas 4L/G8BAG, offers a practical solution for hams with limited space and materials. This "flower pot" design utilizes common hardware store items such as 60mm plastic drain pipes and 75 Ohm coax cable, demonstrating that effective HF operation doesn't require specialized components. The author details the coax preparation, including stripping the outer sleeve and braid at specific measurements like **2510 mm** and 2450 mm, and integrating it into the pipe structure. The construction emphasizes simplicity and low cost, providing an accessible path to getting on the air on the 10m band, especially when a horizontal beam is not feasible. The article notes an SWR of _1.5:1_ with 75 Ohm coax, managed by an MFJ 258 for impedance matching. This temporary solution proved robust, withstanding various weather conditions and achieving contacts across continents, including W, VK, BG, G, JA, and VR2, using 100W SSB from Georgia.

This article documents the author's journey in building, modifying, and testing a DIY short vertical antenna for 40, 30, and 20 meters, with potential 80m capability. Initially inspired by Parks On The Air (POTA), the author explores pedestrian mobile operation and details various experiments to enhance antenna performance. The piece highlights challenges, SWR tuning, portability, and practical results, emphasizing a balance between efficiency and size. Ultimately, it showcases the adaptability of DIY antennas for portable ham radio applications.

Remotely monitor the output power and SWR of your station via a web browser. WT32/ESP32 based project, combined with a directional coupler setup. It reads two voltages which are supplied by the directional couplers. From these, the respective power is calculated with the help of a calibration data table to be created by the user.

The _G3TSO_ Mobile Antenna Page details construction and tuning methods for mobile antennas operating across **10 to 160 metres**. The content describes a Hustler-based design, optimized for RF performance and vehicle speeds, featuring centre loading. For optimal operation on various bands, the loading coil placement requires clearance from the vehicle body. Antenna resonance is critical for efficient mobile operation. A mobile antenna's base impedance may be as low as 27 ohms, requiring specific matching to achieve maximum radiation, as a minimum SWR at the transmitter does not always indicate resonance or maximum output. Tuning involves physical adjustment of antenna length to achieve resonance at the operating frequency. The _G3TSO_ page outlines a tuning procedure utilizing a low-power signal source and a field strength meter to identify maximum radiation before impedance matching. Loading coil placement, either at the base, center, or top of the antenna, influences radiation efficiency and mechanical stability for mobile installations. Centre-loaded whips, such as the Hustler design, offer a compromise between efficiency and stability, often for single-band operation. Helically wound antennas, including those for **28 MHz**, may present base impedances around 17 ohms, resulting in a 3:1 SWR at resonance. Low resistance grounding at the antenna base is also specified for optimizing performance and minimizing RFI during mobile operation. DXZone Focus: Mobile | Any | Antenna Tuning | HF

This is a simple 2.4 GHz SWR meter which is based around surplus microwave hardware which can be easily found. The main component is a MECA -20/-20 dB Directional Coupler which has a frequency range of approximately 700 MHz to 2.5 GHz.

Presents a detailed construction guide for a 9 dB, 70cm collinear antenna, utilizing readily available _RG58/U_ coaxial cable and PVC pipe for housing. The resource outlines the critical calculations for ½ wavelength sections at 444 MHz, incorporating the coaxial cable's velocity factor of 0.66, which yields a section length of 223 millimeters. It specifies the preparation and soldering of eight such half-wavelength sections, each cut to 231mm to allow for trimming, forming the core of the array. Further instructions detail the integration of a ¼ wave element (169mm #16 solid wire) at the top and a ¼ wave aluminum tube (160mm, 5/16 inch) at the bottom, crimped to the feed point's braid. The guide also addresses RF common mode current suppression by suggesting the use of _FT50-43_ toroids on the feedline. Final assembly steps cover mounting the antenna within ¾" PVC pipe using a wooden dowel, waterproofing connections, and initial SWR checks. The article also discusses scaling the design for different element counts and other VHF/UHF bands.

This utility program shows the impedance and reflection coefficient parameters (SWR, reflection coefficient magnitude Rho, or Return Loss RL in dB) at both ends of a transmission line and the details of power loss in the line. It includes built-in specifications for approximately 100 different line types. You can modify the specs to see how small changes affect the results or to specify custom lines. All program inputs may be changed directly or you can use spin buttons to make the changes.

The Portable EFHW antenna for the 40, 20, 15, and 10-meter bands utilizes a broadband transformer with a 1:49 ratio, designed on a PCB by either Jan or DL2MAN. The design incorporates an **FT114 core**, offering an alternative to the FT82 core. The antenna requires precisely 20.5 meters of DX Wire Ultralight for optimal performance. Additional components include DX Wires "Dyneema" 1mm rope and 1mm bricklayers string for structural support. The SWR plot indicates performance at two elevation heights: 5.5 meters (blue line) and 4 meters (yellow line), demonstrating optimization for low-elevation portable use without poles. The antenna's components, including spool and rope tensioners, are available for 3D printing, with spool dimensions scaled to 130% for a length of approximately 110mm. The design emphasizes simplicity and portability, suitable for field deployment.

When building antennas for the Wifi band (Like the 8dBi omni), a need for an easy way to check the antennas arose. A Voltage Standing Wave Ratio (VSWR) meter useable at the 2.4GHz band is however, hard to find.

The 1/4 wavelength vertical antenna project, initially designed for 20 meters, has evolved into a versatile portable solution covering 10 through 60 meters. K0BXB details its construction, emphasizing a bottom-loaded design with a tapped loading coil and four 10-foot counterpoise wires. The author shares personal experiences and field results, including **18 QSOs** during a park activation on 17m and 30m with 10 watts, and a **2,435-mile** contact with a contest station in Bonaire on 20m using 5 watts. Comparisons are drawn to commercial offerings like the _Wolf River Coils TIA_ and _QRPGuys Triband Vertical_, highlighting the DIY antenna's small footprint, light weight, and ease of tuning for POTA activations. The resource includes insights into using test equipment such as the _NanoVNA_ for SWR optimization and discusses various radiator lengths, from 17-foot wire to a 102-inch whip, demonstrating adaptability for different portable setups. Construction tips cover coil winding, tap placement, and connecting feedlines and radials using common components.

Constructing a 5-element quad antenna, the author aimed for low cost and simplicity, resulting in an effective design with 11 dBi gain and SWR of 2:1 or better across the 2-meter band. Using wood and dowels, the antenna costs under $8 and takes less than two hours to build with basic tools. The model predicts excellent performance, confirmed by ARRL Lab measurements. Practical field results demonstrate improved communication, even in simplex mode.

Presents an interactive online **Moxon antenna designer** tool, enabling radio amateurs to configure and analyze lightweight Moxon antennas for HF and VHF bands. Users can specify design frequency, element lengths, wire diameter, insulation, and support height. The tool visualizes the antenna in interactive 3D graphics and generates comprehensive performance charts, including azimuth, elevation, 3D, and polarization radiation patterns, VSWR charts, antenna current diagrams, and Smith charts. It also allows selection of various ground types (e.g., very poor soil, salt water, free space) to model environmental effects on antenna performance. The designer provides insights into how physical dimensions and ground conditions influence key antenna parameters like forward gain, front-to-back ratio, and feed-point impedance, which is typically close to 50 ohms. It also includes a feature to model the effect of coaxial cable losses on **VSWR** at the transmitter end, distinguishing it from the feed-point VSWR. This helps operators understand the actual radiated power efficiency versus the apparent match at the transceiver, offering a practical perspective on antenna system performance in portable operations.

This article details a ham radio operator’s experience setting up HF antennas in an antenna-restricted community. Initially using an AEA Isoloop magnetic loop for QRP PSK, the author later built an attic antenna system, including dipoles for multiple HF bands and a slinky dipole for 40 meters. The setup allowed for operation on six bands with acceptable VSWR. Despite space constraints and some compromises, performance was effective. The article highlights practical strategies, emphasizing experimentation and antenna modeling for optimizing performance in limited-space environments. A valuable guide for ham radio operators facing similar restrictions.

This page provides construction details for a 4-element 10-meter Yagi antenna with 28 Ohm impedance. It includes information on the elements, positions, diagrams, and data related to frequency, gain, front-to-rear ratio, radiation resistance, SWR, and loss. The content is aimed at hams or radio operators interested in building and optimizing Yagi antennas for the 10-meter band.

Addresses the common challenge of constructing effective dual-band antennas for VHF/UHF operations, specifically detailing a J-pole design. It covers the theoretical underpinnings, including calculations for quarter-wavelength radiator and stub sections, accounting for velocity factor and design frequency. The resource provides practical construction guidance using readily available materials like TV twin lead and coaxial cable, culminating in an antenna with a total length of approximately 52 inches. Performance metrics are presented, showing a measured SWR of 1.7:1 or better across most of the 2-meter band and less than 2:1 across the 70-cm band. These SWR measurements, referenced to 50-ohm impedance, were taken at the transmitter end of the feed line. The article also touches upon the necessity of a balun for proper impedance matching between the balanced J-pole and unbalanced coaxial feed line, suggesting a split-core cylindrical ferrite for this purpose.

The article describes a high-gain, compact beam antenna design for the 2-meter band (144-146 MHz). The NSH 4x4 Boomer is a 4-element antenna that is mounted on a 4-foot boom with an 8.2 dB gain, 1.2:1 SWR, and a front-to-back ratio of 18 db. It is designed for mobile operations and little area, making it perfect for field usage such as disaster management. The design employs regularly spaced parts with a straightforward gamma match for tuning, and the construction materials include a square boom and polished aluminum tubes. In local and portable tests, the antenna worked regularly, achieving contact distances of up to 15 kilometers.

This project describes the construction of a W3HH (T2FD) antenna for HF bands (3-30 MHz). While less efficient than a tuned dipole, it offers broad frequency coverage with a maximum SWR of 3.4 and reduces QRM (noise) significantly. On the 80-meter band, it shows slightly weaker signals than a dipole but with improved signal-to-noise ratio. The design includes non-inductive resistors, a 13:1 balun, and a "frog ladder" transmission line. Though not a high-performance antenna, it is compact and versatile, making it ideal for wide-band HF communication. Article in French

The document provides a detailed modification guide for the Zetagi HP201 SWR Wattmeter, converting it for HF amateur band usage. It replaces the original circuit with a Tandem Coupler based on the Sontheimer and Frederick directional coupler patent, enhancing accuracy and sensitivity. Key components include Murata toroid cores, scaling resistors, and a new calibration process. Challenges and solutions during the modification process are discussed, ensuring linear results across 160-10m bands. This guide also includes calibration instructions and theoretical insights into the coupler's operation.

Learn how to design a Hentenna antenna, a portable asymmetrical double-loop antenna ideal for amateur HF or VHF bands. This page provides details on constructing and optimizing the antenna for maximum performance in DX communications. Discover how altering the antenna's vertical feed section can adjust the VSWR resonant frequency and how changing the support pole's position can alter the beam direction. Originally developed by Japanese 6-meter operators, the 'Hentenna' offers a unique design that allows for horizontal polarization when vertically oriented. Explore radiation patterns, VSWR charts, and antenna currents diagrams to optimize your antenna's performance for long-distance contacts.

Optimizing directional gain on the 40-meter band often involves complex antenna designs; this resource details the construction and performance of a reversible _Moxon_ array. The design provides directional coverage from southeast to west, with a switching mechanism to reverse the pattern towards east to northwest. Key design considerations include precise element spacing, the critical role of coil inductance for proper resonance, and the use of _NEC5_ for accurate electromagnetic modeling, ensuring the antenna performs as predicted across the desired frequency range. The antenna's performance is evaluated through on-air contacts, demonstrating effective signal propagation to regions like the Caribbean, South/Central America, the US, and Europe. The article presents measured SWR plots and gain patterns, comparing them against the _NEC_ model predictions to validate the design's efficacy. Practical application notes cover mounting considerations and the benefits of its reversible pattern for targeted DXing on 40 meters, offering a robust solution for operators seeking enhanced directional capabilities without a full-sized rotating Yagi.

This page provides guidance on designing an End-Fed Half-Wave (EFHW) or Random-Length antenna for amateur HF bands, such as 80 or 40 meters. The content explains how to optimize the antenna for multi-band use and match it to a 50-ohm system using an unun. Hams can generate radiation patterns, VSWR charts, and antenna current diagrams for their customized antenna designs. Understanding how antenna dimensions affect performance is essential for successful field operations. The page caters to ham radio operators looking to build efficient and effective HF antennas for their stations.

Details the construction of a portable 6-meter 4-element quad antenna, specifically designed for VHF and Field Day operations. The design emphasizes portability and rapid field assembly, utilizing a 10-foot boom, #12 bare wire elements, and fiberglass electric fence post spreaders. It presents specific dimensions for reflector, driven element, and directors, including spreader lengths, circumferences, and corner marks, all derived from a G0KSC design and modeled in EZNEC. The resource outlines the fabrication of synthetic lumber hubs that allow post-assembly adjustments along the boom, and describes spreader clamps made from ¾” OD fiberglass rod, drilled and tapped for 8-32 nylon thumbscrews to secure element wires. It provides instructions for reducing spreader ends to 0.370” OD for proper fit and details the assembly of the boom from two 1½” OD x 6’ aluminum tubes. Performance data from EZNEC modeling indicates a gain of 10.25 dBi (8.1 dBd) and a 20 dB F/B ratio at 50.150 MHz, with SWR values of 1.08, 1.09, and 1.11 at 50, 50.15, and 50.5 MHz respectively. The document includes a field test report from Field Day 2010, where the antenna was deployed at 21 feet, showing an SWR resonance 200 KHz below EZNEC predictions. It notes successful 5-watt QSOs into New York and Canada from Tennessee, highlighting the antenna's excellent directivity and gain compared to a 4 dBd Moxon. The antenna breaks down into easily transportable components, including two 5’ boom sections, a 3’ boom connector, 16 spreaders, and four element/spreader clamp assemblies.

Fifty-one MHz operation, often called the "magic band," benefits significantly from a well-designed antenna, and this resource details the construction of a rigid 6-meter _Moxon antenna_ using common DIY store materials. The author, 4L/G8BAG, shares his experience with the 6m band, highlighting its potential for long-distance contacts, with single-hop sporadic E propagation enabling QSOs up to **2,500 km** and multi-hop contacts reaching **10,000 km**. The project emphasizes cost-effectiveness and durability, utilizing yellow gas pipe with an internal stainless steel lining for the antenna elements. The article provides specific dimensions for the Moxon rectangle, derived from the 12mm internal diameter of the gas pipe's steel core, rather than the outer plastic. It also details the use of white PVC water pipe for insulators and mounting, ensuring a tight fit with the yellow gas pipe. Initial testing with an MFJ antenna analyzer showed an excellent 1:1 SWR across the 50-52 MHz range, even when using 75 Ohm satellite cable as a feeder. The construction process is straightforward, involving cutting and bending the gas pipe, fitting insulators, and connecting the feedline. The author's successful on-air results, including a 1000 km contact with a temporary vertical, underscore the effectiveness of the 6m band and the Moxon design. The resource concludes with a note on exploring heavier gauge gas pipe for future 10m antenna projects.

The author explores enhancing the performance of a 7-meter fiberglass squid pole wire antenna for amateur radio. The wire, resonant at 10MHz, poses impedance challenges on various bands. Experimenting with direct coax feed and UN-UN transformers, the LDG Z11-Pro2 auto-tuner is found effective but may show deceptive SWR readings. The author employs adjustable UN-UN ratios and introduces a custom "porcupine" coil to optimize the antenna's efficiency.

The _MFJ-915_ RF Isolator, rated for 1.8-30 MHz and 1500W PEP, exemplifies the product range available from The Ham Shop. The inventory includes various antenna support ropes, such as 3/16" _Dacron Polyester Rope_ in lengths from 100 to 1500 feet, alongside a selection of cables for _SignaLink USB_ sound card interfaces. Specific SignaLink cables are offered for radios like the Yaesu FT-847 (SLCAB847), Yaesu HTs (SLCABVXY), and the Elecraft K3 (SLCABHTY). Additionally, the shop provides modular jumper cables and modules, including the SLMOD8RY for Kenwood/Alinco 8-pin round mic jacks and the SLMOD8RI for Icom 8-pin round mic jacks. The product line supports diverse station configurations, encompassing antennas, coax, baluns, dummy loads, duplexers, insulators, microphones, power supplies, SWR meters, and watt meters.

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 page provides information on how to design an Off-Center-Fed Dipole (OCFD) antenna, suitable for amateur HF bands like 80 meters or 40 meters. The antenna design allows for VSWR minima on multiple bands, making it a good choice for multi-band use. Learn how to create an OCFD antenna in either flat-top or inverted-Vee form using a single support. The page also offers tools to generate radiation patterns, VSWR charts, and antenna current diagrams for your specific antenna design, helping hams understand performance factors. Ideal for ham radio operators looking to build their own effective antennas.

This article presents a novel Top Loaded End-Fed Half-Wave (TLEFHW) antenna design for 20-meter ham radio operation. The antenna features a compact 14-foot vertical radiator with a capacitance hat configuration, eliminating the need for radials or ground systems. Using EZNEC modeling and field testing, the design achieves a 1.5:1 SWR across the 20m band with a 4.11 dBi gain. Key features include quick deployment, lightweight construction, and directional radiation pattern with 110-degree beamwidth. The design, while requiring a 45-foot footprint due to the top hat, offers an effective portable solution for amateur radio operators seeking a no-ground, no-tuner 20m antenna option.

This report details a modification of a Diamond V2000 antenna, replacing its original two 0.50 m radials with two 1.55 m radials. Initial M5-threaded rods failed to fit; the housing required M6 threads. Custom radials were made using 8 mm OD aluminium tubing and M6-threaded stainless steel ends, secured with nuts machined to 9 mm. SWR issues on 6 m (>2:1) were largely due to a poor counterpoise connection, resolved during reassembly. NanoVNA measurements showed no adverse effects on 2 m or 70 cm. The final setup retains the two 1.55 m radials and original counterpoise. Other operators reported SWR degradation with similar mods—sometimes fixed by adding capacitance—but this was not observed here.

Effective suppression of harmonics and parasitic radiation from HF transmitters is crucial, especially with the increasing sensitivity of VHF/UHF radio channels to interference. This project details a hybrid low-pass filter (LPF) designed to operate across the HF bands up to 51 MHz, making it suitable for 6-meter band operations while providing deep VHF/UHF suppression. The design addresses the challenge of modern interference landscapes, where even microvolt-level signals can disrupt wireless sensors and other simple VHF/UHF receivers. The filter utilizes a single elliptic link, combining high cutoff steepness with robust suppression in the hundreds of megahertz range. A key feature is the use of only two standard capacitor values, simplifying construction and component sourcing. The article provides a detailed schematic, performance characteristics, and _RFSim99_ model file, demonstrating a reflection coefficient S11 below 0.017 (VSWR < 1.03) across 1-51 MHz, ensuring minimal degradation to the antenna system. Construction notes include coil winding specifications and capacitor selection guidance, with recommendations for _FR-4_ assembly. Two capacitor sets are presented, with the first variant recommended for its lower RF current demands, keeping currents below 3 A at 1 kW passing power at 51 MHz. Fine-tuning involves adjusting frameless coils, with considerations for capacitor tolerance and high-frequency capacitance measurement accuracy.

This project presents a compact QRP SWR meter featuring a 0.96" OLED display (128x64 pixels) for high-contrast visibility, updated with software fixes for display compatibility, improved low-power performance, and support for ATtiny45/85 microprocessors. A 1.3" OLED version accommodates visibility needs. Designed for HF QRP transmitters (3-15W), it uses a Breune coupler with germanium diodes for accurate SWR measurement. Powered by a AAA battery, the meter offers a standalone solution for impedance matching, with a 3D-printed enclosure enhancing portability.

Fully functional weathervane conceals an efficient 2- meter base-station antenna. Your Neighbors and HOA won’t know it’s there and they will love the rooster-vane. The Rooster-Tenna is a covert 2-meter ham radio antenna disguised as a functional weathervane, ensuring seamless integration into residential environments. This improved version features a wide-spaced parallel-fed folded dipole in a compact skeleton slot design. Constructed from aluminum tubing and acrylic supports, it offers omnidirectional, vertically polarized performance suitable for repeater and satellite use. Easy to mount and tune, it achieves a low SWR across the 2m band. With 3D-printable parts available, the Rooster-Tenna blends practicality with stealth, making it an ideal solution for HOA-restricted areas

The article explores the concepts of return loss, VSWR, and S11 within the context of microwave engineering, highlighting the confusion arising from their definitions. It clarifies that these parameters, while seemingly distinct, fundamentally describe the same phenomenon related to wave reflection and transmission in microwave circuits. The discussion emphasizes the historical context and mathematical relationships among these terms, revealing that their interpretation can vary significantly across different engineering disciplines. Ultimately, it advocates for a pragmatic approach to using these parameters based on familiarity rather than strict definitions.

Presents the design and construction of a folding 5-element Yagi antenna specifically engineered for 144 MHz portable operation, particularly for VHF contest Rover categories. It details element dimensions, boom construction using ¾-inch pine, and a folding mechanism that reduces the 52-inch boom to 26 inches for transport. The document provides a table with precise element distances and lengths, including a 2.4 mm length correction for solid parasitic elements, and specifies the use of 3/16-inch solid aluminum for parasitic elements and brass tubing for the driven element. It also covers the bent dipole driven element design for impedance matching, balun implementation with Type 31 ferrite beads for common mode current suppression, and weatherproofing for the feed point. The resource includes predicted performance data from 4NEC2 modeling, showing SWR and return loss characteristics, as well as gain and front-to-back ratios at various frequencies across the 2-meter band. It reports a measured SWR of 1.2:1 at 144.2 MHz and 1.5:1 at 147 MHz, corrected for 25 feet of RG-8/M coaxial cable loss. The design offers approximately 1.5 dB more gain than a previous 4-element design, maintaining a decent SWR up to 147 MHz, and was successfully deployed in a winning June 2016 ARRL VHF Contest Rover entry.

This article describes the design and construction of a 4-meter band vertical sleeved dipole antenna, built to complement a newly acquired Yaesu FTDX10 transceiver. The simple yet effective antenna consists of modified coaxial cable housed in weather-resistant plastic conduit, featuring an integrated 8-turn choke coil. Despite common misidentification as an EFHW antenna, this design is actually a sleeved dipole that provides an excellent 50-ohm match across the band, achieving SWR values between 1:1 and 1.1:1. The project demonstrates an economical approach to entering the relatively quiet 4-meter band.

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.

An Arduino-based interface provides a remote tuner call command for Icom **IC7700** and **IC7800** transceivers, addressing the lack of a built-in function for external tuners such as the MFJ 998RT. This setup initiates a low-power transmit signal, typically 15 watts, allowing the remote autotuner to perform its matching sequence. The article details the required CI-V line communication and modifications to existing Arduino code, specifically referencing contributions from Jean-Jacques ON7EQ for improved Icom interrogation routines. The system involves a sequence of steps: storing the transceiver's current mode and power, disabling the internal autotuner, activating a control relay to interrupt the amplifier line, switching to RTTY mode at low power, and initiating transmit. The transmit duration is manually controlled by the operator, observing the SWR meter until a low SWR is achieved, then a second button press stops the transmission. A built-in 4-second transmit limit provides a safety measure. After tuning, the routine restores the original mode and power settings, re-enables the internal autotuner, and performs a brief 2-second RTTY transmission for internal tuner adjustment. The circuit diagram includes a Panasonic form 2 relay for amp control and emphasizes critical delays in the Arduino code for stable operation at 9600 baud CI-V communication. Compatibility with logging software like DXLab, N1MM, and N3FJP is noted, with specific interrogation time settings required to avoid conflicts.

Constructing a **J-Pole antenna** from 450 Ohm ladder line for 2-meter (144 MHz) and 70-centimeter (440 MHz) operation involves specific calculations and assembly steps. The design, based on an earlier KD6GLF concept using 300 Ohm twinlead, features a ¾ wavelength radiator and a ¼ wavelength matching stub, functioning as an end-fed half-wave antenna without requiring ground radials. It offers a gain of 2.4 dB over isotropic. The resource provides the formulas for determining the lengths of the ¾ wave radiator and ¼ wave stub, incorporating a velocity factor of 91% for 450 Ohm ladder line. For 146 MHz, the radiator measures 55 3/16 inches and the stub 18 3/8 inches. Construction details include cutting a 57¾-inch piece of ladder line, stripping 4 inches from one end, and attaching a 24-inch section of RG58 or RG8X coax with a 3-5 turn RF choke. SWR adjustment is achieved by sliding a shorting bar or by incrementally trimming the elements at a 1:3 ratio (stub to radiator). The goal is a 1:1.1 SWR at 146 MHz, which typically yields 1:1.2 at 446 MHz. The article also discusses power handling, noting that while 10-15 watts is fine, 50 watts may increase SWR to 1:2.1, and advises keeping the antenna away from other objects to prevent coupling and SWR degradation.

Demonstrates various technical projects and tutorials for amateur radio operators, focusing on digital modes, monitoring, and station setup. It covers topics such as implementing a _WSPR_ station, setting up ADS-B reception, configuring a _DXSpider_ cluster, and utilizing monitoring tools like Prometheus and Grafana. The resource provides practical guides for integrating modern IT solutions with ham radio activities, including Docker and Linux environments for radio applications. This site also features a publicly accessible online logbook, offering detailed statistics on QSOs by band, mode, and geographical zone, with visual mapping of contacts. It includes a comprehensive amateur radio lexicon, explaining hundreds of terms, and provides a real-time display of the F4HXN station's local weather conditions. The resource also aggregates information on upcoming ham radio events and offers a **SWR simulator** for antenna analysis, allowing users to visualize ROS changes based on frequency and antenna parameters.

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 Open NEC2 Viewer for Android provides a mobile platform for **NEC2** antenna modeling, enabling users to visualize and analyze antenna designs directly on their devices. It integrates the robust NEC2 computational library, leveraging the Method of Moments for full-wave electromagnetic analysis, and utilizes the Google Filament renderer for interactive 3D visualization of antenna structures, segmentation, and wireframes. The application facilitates the calculation of geometric parameters and antenna characteristics across specified frequency ranges. Key functionalities include parametric analysis, offering real-time computation of **radiation patterns** (RP), antenna gain, Voltage Standing Wave Ratio (VSWR), and input impedance. Users can configure flexible calculation settings to control scan step, frequency range, and various control cards, allowing for detailed electromagnetic analysis tailored to specific design requirements. Designed for radio engineers, antenna developers, radio amateurs, and students, the app is distributed as open-source software under the GNU General Public License v3.0. It provides a portable and accessible tool for electromagnetic modeling, making advanced antenna analysis capabilities available on Android devices.