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A Variable Base-Loading-Coil provides a practical solution for optimizing HF mobile whip performance across multiple bands. The design, as presented by VK4ADC, details a coil wound on a 50mm PVC former, utilizing 1.6mm enamelled copper wire for robust construction. This approach allows for precise tuning, a critical factor in achieving efficient radiation from a mobile setup, where antenna length is often compromised. My own field experience with similar base-loaded whips confirms the importance of a well-designed loading coil for maximizing signal strength and minimizing SWR. The VK4ADC design incorporates a sliding contact, enabling continuous adjustment, which is superior to fixed taps for fine-tuning resonance on the fly. This variable inductance allows the operator to quickly adapt the antenna to different HF segments, from 80 meters up to 10 meters, without needing to swap out multiple coils. The document includes specific winding data, such as the number of turns per inch and the overall length of the coil, which are essential for replication. It also touches upon the mechanical aspects of integrating the coil with a standard mobile whip, ensuring a stable and weather-resistant assembly for reliable operation during mobile DXing or casual rag-chewing.

The SCOTIA Bandhopper, a multi-band mobile vertical antenna, offers a unique sliding coil design for rapid band changes across 10m to 80m. Drawing inspiration from the classic Webster _Bandspanner_, this design improves efficiency through near-center loading, theoretically achieving up to **2.25 times** greater radiation resistance than base-loaded counterparts. The antenna, extending to approximately 10 feet on 80m, utilizes a 5-foot fiberglass tube with an internal loading coil and a 57-inch tapered steel whip, allowing continuous tuning across bands without changing coils or whip sections. Field results from GM3VLB and the SCOTIA team, based on over 40 years of /M and /P operations, indicate the Bandhopper significantly outperforms shorter mobile whips. Its slim profile minimizes drag, making it suitable for sustained motorway speeds. The design incorporates a novel "fixed spring contact" arrangement for the variable inductance loading coil, with two sets of contacts for 10/12m and 15-80m. Construction details are provided, including materials like boundary marker poles and specific wire gauges, with an estimated build cost of **£20** or less, depending on junk box availability.

The 1960s mobile/base antenna returns, double G Whip for base use.

A very efficient 80 meter Counterpoise antenna designed to reduce ground losses from inadequate radial systems beneath inverted L antennas, a project by DM2GM and DM4IM based on the original K2AV antenna concept.

A 6 dB gain Moxon rectangle antenna, designed for the 2-meter band, offers an excellent solution for hams seeking a compact, directional antenna for **SSB** operation, particularly in restricted spaces like an attic. This design emphasizes ease of construction using readily available materials such as 4mm OD brass tubing and plywood, making it an accessible project for many radio amateurs. The antenna's inherent characteristics, including a high front-to-back ratio of 37 dB and a 50-ohm feed impedance, contribute to its effectiveness in mitigating local noise and focusing radiated power. The project leverages the free MoxGen program for precise dimension calculations based on the desired frequency and wire size, and utilizes 4nec2 for pattern analysis, confirming a 3 dB beamwidth of 80 degrees. Construction involves bending brass tubing for the driven and passive elements, mounting them on an 800 x 350 mm plywood boom, and securing them with cable clips and epoxy resin. Initial SWR measurements at 144.3 MHz showed 1.6:1, which improved to 1.3:1 at 145.3 MHz across a flat band from 144.1 MHz to 145.5 MHz after adding a **coaxial choke** to mitigate common mode current.

Demonstrates how to construct an automatic band decoder, moving beyond manual selector switches for antenna and filter control. It addresses the challenge of varying band data outputs from different transceivers: Icom rigs provide voltage values, Yaesu rigs use Binary Coded Decimal (BCD), and Kenwood rigs lack direct band data output. The resource highlights a clever solution utilizing logging software like _CT (K1EA)_ and _DX4WIN_ to emulate Yaesu's BCD output via a PC's printer port, making the decoder compatible with any rig. The author details experiences building decoders based on designs by Bob _K6XX_ and Guy _ON4AOI_, noting K6XX's simple TTL chip design and ON4AOI's more comprehensive, opto-isolated unit capable of controlling ten outputs and bandpass filters like the _Dunestar_. It also references a _W9XT_ board design, which Steve Wilson, G3VMW, modified with BD140 transistors for source drivers, emphasizing safety. The author successfully cased an ON4AOI-based decoder in an old modem case, connecting it to an FT1000MP or a PC printer port to drive remote relays and a Dunestar Band Pass Filter.

This project details the construction of a **full-sized 40-meter vertical antenna**, born from a renewed interest in 7 MHz operation and a desire for improved effectiveness over simple dipoles. The author, K5DKZ, initially focused on VHF experimentation, which provided an inventory of aluminum tubing and fiberglass spreaders for this endeavor. Before this vertical, K5DKZ utilized an 80/40 meter inverted-vee trap dipole and a 40-meter broadband dipole, but now primarily uses a pair of full-sized, phased, quarter-wave verticals spaced 35 feet apart for serious 40-meter work. The construction involves a base-heavy design for stability, using a 44.5-inch section of 1-1/4 inch steel TV mast driven into 1-3/8 inch aluminum tubing, insulated by a 105-inch section of Schedule 40 PVC pipe. The assembly reaches 31 feet, close to the 32 feet required for a quarter-wavelength on 40 meters, with fine-tuning achieved by winding wire onto a fiberglass spreader. The design is explicitly presented as a foundation for a two-element 40-meter Yagi beam, outlining modifications like substituting aluminum for steel in the base and using an inductive hairpin match for the driven element. The article also discusses tuning considerations for a large 40-meter beam, noting the 100 to 200 kHz upward frequency shift when raised, and suggesting methods for installation on a tower. The author emphasizes the cost-effectiveness and good performance of the monopole approach, especially when multiple verticals are needed.

A DIY guide to build your own compact multiband HF antenna based on the G3TXQ version using a 1:4 balun. This article includes the full part list and instructions to assembly, including the center plate.

A home made antenna tuner based on the W6JJZ basic concept that ,atches balanced loads without the use of lossy baluns, can provide band-pass filtering and harmonic attenuation.

The AE6AC 17-meter Moxon antenna project details the construction of a wire beam using readily available materials. This design utilizes four 16-foot fiberglass crappie poles for support, joined at the center with 3/4-inch Schedule 40 PVC pipe and "T" slip fittings. Wire segment lengths for 18.135 MHz were calculated using _Moxgen_ software by AC6LA, with specific dimensions provided in feet and inches for precise cutting. Key construction decisions include joining the crappie pole bases into a central hub and attaching the 16-gauge silver-plated copper wire to the pole ends. Dacron cord with a fisherman's knot secures the wire to the pole tips, while small wire loops at the corners maintain antenna shape. Plexiglas pieces serve as insulators for sections "A" and "C." The finished antenna, weighing less than 10 pounds, mounts on a fiberglass windsurfer mast and incorporates a 1:1 current mode ferrite bead balun. Performance measurements with an _MFJ-259B_ show an SWR better than 1.5:1 across the 17m band, with good front-to-back ratio and reported signal strength improvements of 2-4 S-units over vertical dipoles. Initial contacts included VK2AXB, ZF6GS, and KL1M.

Communication scanners, antennas and cables canadian dealer based in Norwich Ontario

A 5 elements homemade DK7ZB yagi antenna for 4 meters band based on a 50MHz TONNA

Amateur Radio HF Cubical Quad and Delta Loop antennas manufacturer based in Spain

An interesting article on loading short vertical monopole antennas, representing six different methods. Base loading, Center Loading, Top Loading, Continuous loading, half and half loading and capacitive top loading.

Fabricates baseplate components, and provides hardware kits for DIY hex beam, spiderbeam and moxon antennas.

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

A Compact and efficient multiband beam antenna based on a Modified W8JK Array by K5LJ

A vertical antenna for Six Meters band

A step by step approach for a ham radio vertical antenna mount using only a hole, gravel and a piece of plumbing pipe

A 10mm thick aluminum plate serves as the foundation for a homemade hexbeam antenna, designed to support the central mast and six radiating elements. The construction details include precise drilling for the central mast and the six fiberglass spreaders, ensuring proper alignment and mechanical integrity. The author, FY8PE, shares insights from his experience, emphasizing the importance of robust materials for long-term outdoor deployment. The design incorporates a specific arrangement for the spreader attachment points, allowing for easy assembly and maintenance of the hexbeam's unique geometry. While specific performance measurements are not detailed, the focus on structural strength and material choice suggests an emphasis on reliability in various weather conditions. The project provides practical guidance for hams looking to build a durable hexbeam base.

LnR Precision Inc. is a North Carolina based company that specializes in Par EndFedz amateur radio antennas and MantiZ QRP Transceivers. Their most popular products include End-Fed QRP portable antennas and HF FX Series QRP Transceivers.

This web article by VK3BLG details the construction of an experimental 70cm (432 MHz) circularly polarized patch antenna, intended for satellite communication. The resource provides dimensions, feed point specifications, and impedance matching considerations for a single patch element, with discussion extending to array configurations for circular polarization. Construction involves a copper patch element on a dielectric substrate, fed via a coaxial cable. The design is based on information derived from AO-40 satellite antenna specifications, focusing on achieving circular polarization for satellite reception. The article includes specific dimensions for the patch and feed points, along with impedance values. Validation is implied through on-air satellite reception reports, with initial signal reports of **1 S-point above noise** for AO-40 beacons using a grid reflector, improving to **3-4 S-points above noise** with a 2-turn helical feed. The author references a _NanoVNA_ for impedance measurements and discusses the relationship between slot and dipole antennas in the context of patch design. DXZone Focus: Web Article | 70cm Patch Antenna | On-Air Satellite Reception | Circular Polarization

European supplier of radio communication receivers and scanners, transceivers, antennas, cables, connectors, GPS and accessories based in Prhaha Czeck republic.

A system designed to automatically tune small transmitting magnetic loop antennas, particularly beneficial for **contest operations** where rapid frequency changes are common. The core of the system involves a PC-based control application, AutoCap, written in C#, which monitors antenna SWR via an external meter and commands a motor interface to adjust the loop's variable capacitor. The software is compatible with Windows and Linux via the Mono framework, offering a graphical user interface for monitoring system status, SWR, power, and motor commands. Key components include one or more magnetic loop antennas equipped with DC or stepper motors for capacitor adjustment, an SWR meter with data output (such as the Telepost LP-100A or a homebrew serial/USB SWR meter), the AutoCap PC software, and a motor interface. The most effective motor interface utilizes an **Arduino-based controller** with custom firmware, providing precise control over both simple DC motors and stepper motors, and supporting features like motor braking for finer adjustments. The system allows for configurable SWR thresholds, pulse widths, and motor effort settings to optimize tuning speed and resolution. Optional radio integration provides frequency hints, enabling the algorithm to learn the relationship between motor actions and resonant frequency, thereby speeding up initial tuning responses. The software also supports antenna profiles, allowing operators to save and recall specific configurations for different loops, including accumulated frequency hint data.

This is a one for all antenna tuner with wide range tuning on all the HF bands. The tuner is based on a G3WQW design. DIY project by PD7MAA

Aduino-based Amateur Radio Antenna Rotator Controller that can emulate the Yaesu GS-232A or GS-232B interface by K3NG

The fan dipole antenna as an alternative to the paralled dipole antenna, to achieve a larger bandwidth and a better tuning by decreasing elenment influences.A project based on the W6HDG original concept.

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

Operating magnetic loop antennas requires careful consideration of RF safety, particularly regarding near-field magnetic field intensity. This resource presents calculations for magnetic field strength (H-field) at various distances from a magnetic loop, emphasizing that the H-field is significantly higher than the E-field in the near-field region due to the inductive nature of the radiating element. It provides specific formulas and examples for determining safe operating distances based on power levels and loop dimensions, crucial for compliance with RF exposure limits. The analysis compares calculated H-field values against FCC and ICNIRP maximum permissible exposure (MPE) limits for controlled and uncontrolled environments. It demonstrates that even at QRP power levels (e.g., 5W), the H-field can exceed MPE limits within a few feet of the antenna, necessitating greater separation distances than often assumed for electric field considerations. The practical application of these calculations helps amateur radio operators configure their stations to ensure personnel safety and regulatory compliance when deploying compact, high-Q magnetic loop antennas.

Spipral antenna principle by a concept of Bill Petlowany, K6NO. Tak Antennas are based on this principle, using spirals as dipole linear wires.

Based on a simple project based on a 2 elements Yagi for 20m band, and then becomed a triband yagi with a open-sleeve feed system

An Arduino uno based project to control an MFJ 998 antenna tuner via Icom CI-V interface by VE1ZAC

A ten element ultra-lightweight yagi beam antenna for 144 MHz based on YU7EF design concept

The QRZ.com callsign database serves as a fundamental resource for amateur radio operators worldwide, enabling rapid lookup of station information. Each entry, such as the one for _HB9DSP_, typically includes essential details for making and confirming contacts. Operators can find QSL routes, often indicating preferences like "via bureau or direct," which streamlines the exchange of QSL cards for award credit. Beyond basic contact data, these pages frequently offer insights into an operator's activities, including their participation in contests or DXpeditions. The platform also tracks metrics like "XML Subscriber Lookups," showing how often a callsign's data has been programmatically accessed, totaling **77670** for this specific entry. This functionality is crucial for logging software and other automated systems that rely on accurate, up-to-the-minute amateur radio data. While the page title mentions a "Home made multiband MOXON" antenna, the actual content primarily focuses on the callsign's biographical data within the _QRZ_ database.

Specialize in engineering, design and repair of all rf equipment. Dealer for two way radios, scanners, shortwave radios, wi-fi antennas, wifi amplifiers. Based in Fortuna, California.

Amateur radio accesories, power supplies, electronic parts, antenna controllers and antennas manufacturer based in Spain

Operating a modern amateur radio station often involves integrating various software tools, and LogHX aims to provide a unified environment for Windows users. The software facilitates comprehensive QSO accounting, allowing operators to track contacts and manage both e-QSL and traditional paper QSL exchanges, including via QSL managers or direct methods. It also offers real-time QSO preview and integrates with popular callbook data for quick lookups. LogHX supports various logbook database searches and maintains statistics for numerous awards, a critical feature for serious DXers and contesters. The program handles logbook import and export in widely used formats such as _ADIF_ and _Cabrillo_, ensuring compatibility with other logging applications. Furthermore, it interoperates with Telnet clusters and third-party ham radio software, enhancing its utility in a networked shack environment. Key functionalities include antenna rotator control, editable macros for PSK, RTTY, CW, and SSB operations, and CAT control via _OmniRig_ or direct interfaces. Embedded modules like MMVari, MMTTY, and CWServer streamline digital mode operations, while its multi-window structure allows users to customize their screen layout, preserving valuable monitor space.

Supplier of two-way radio products and accessories to large and small businesses, volunteer groups, radio amateurs and individuals. Transceivers, receivers, antennas cw keys based in London UK

The official web-site of the firm IK-Telecom, Finland, manufacturer of base station antenna-feeder systems

A portable VHF yagi antenna designed for SOTA operations based on the orignal DK7ZB concept.

Six elements yagi antenna for 6 meters band. This antenna design is based on the QuickYagi 4 software by WA7RAI, uses a 6.5 m boom, feature 12.0 dBi gain and 35dB front/back

Ham Radio Antenna parts and kits manufacturer, based in Germany

GAL-ANA is an Antenna-Analyzing Tool software, based on NEC2/MININEC3m engines currently available in demo mode for download

A low-cost SWR meter project based on Arduino that works with AutoCap automatic antenna tuner for magnetic loop antennas

The function of the XPhase is based on the fact that the interfering signal, received by an auxiliary antenna, is added phase-shifted to the signal received from the main antenna. When the phase-shift is more or less 180°, the interfering signal is canceled out.

Valcom Guelph specializes in the design and manufacturing of a full range of MF Beacon 100 KHz - 600 KHz, AM Broadcasting 540 - 1700 KHz, HF 1.8 - 30 MHz, VHF 30 - 300 MHz and UHF 300 - 1,200 MHz and SHF up to 6 GHz antennas based in Canada

Demonstrating the construction of a short dipole antenna tailored for the 60 meter band, this resource provides detailed instructions for radio enthusiasts with limited space. The design incorporates inductive loading using two inductors (L1/L2) made from PVC tubes, allowing for effective operation on 5 MHz. The antenna consists of 12 meters of wire, divided into four sections, with specific dimensions and materials outlined for optimal performance. Results from users indicate that this antenna can significantly enhance DXing capabilities on the 60 meter band. Feedback from operators suggests that while the design is effective, adjustments may be necessary based on individual setups, such as coil diameter and wire gauge. Many users report successful construction and operation, with some experimenting with variations to improve resonance. The practical application of this antenna design has led to successful contacts and improved signal quality, making it a popular choice among 60 meter band operators.

A vertical antenna project for the 7MHz made with some spare parts. Based on a broken 20 foot fishing pole, it is based on a good ground system made with radials and a capacitive hat done to increase the global radiation resistance of the antenna. A custom loading coil is also included in this project to perfectly tune the antenna to the CW portion of the 40 meters band.

Accessories, Antennas and Battery chargers. Radiators, Repeaters, Yagi, Mag, Car, Tetra, Marine, Multiband, Brackets, Mounting accessories, cables and connectors, radiokits, special cables etc. Based in Finland

Super Antenna Systems for HF - VHF - UHF Portable Stealth Mobile Base Backpack EmComm Ham Radio antennas