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The author shares a unique experiment with a 200ft Grasswire antenna—laying wire directly on the ground. Despite inherent losses, the setup enables successful radio communication with a Kentucky station, highlighting the antenna's practicality for portable use with minimal power.

Hostilog, developed by DF1LX using Python 3.5 and PyQT5, is a logging application designed for high-speed QSO data entry, achieving rates of 300–400 QSOs per hour from handwritten logbooks. The software prioritizes keyboard input, minimizing mouse usage for efficiency. It incorporates a cluster window with RegEx filtering capabilities and facilitates UDP transfer of QSO data to _DXkeeper_ from the _DXLab Suite_. The program supports basic rig control via _Hamlib_, with configuration examples provided for radios like the TS-590S using `rigctld`. Hostilog can process 50,000-line ADIF files in under 10 seconds and includes features for combining and sorting ADIF data. While primarily a Windows application, it runs under _WINE_ on Linux, with specific notes on Ubuntu compatibility. Recent updates, including a version from August 28, 2024, address bugs and improve UI, with documentation available in both German and English.

Miniature PIC microcontroller based keyer kit with convenient modes. The kit includes PCB, componets, knob and ready programmed PIC microcontroller. Author make available from his web site Circuit diagram, Component layout,List of components and downloadable Software

Learn how to easily improve your handheld VHF performance on the 2-meter band with the Flowerpot antenna. This simple DIY antenna made from coaxial cable requires minimal tools and materials, providing a big range upgrade compared to standard rubber-duck antennas. Discover how to build, tune, and optimize the Flowerpot antenna for excellent performance. Ideal for hams looking for lightweight, portable solutions for handhelds, mobile rigs, home stations, SOTA/POTA activations, and emergency communication.

CTR2-Mini is a small radio controller based on the Seeed Studios Wio Terminal. It can control many radios including FlexRadio 6000s. Multiple Minis can be used to control multiple slices on the Flex. It also has a special mode that allows two CTR2-Minis to control the Main and Sub VFOs on the FTdx101. An article on CTR2-Mini appears in the September 2022 issue of QST.

SkyRoof is an open-source, 64-bit Windows application designed for amateur radio operators and satellite enthusiasts, combining satellite tracking and Software Defined Radio (SDR) functionality in a unified platform. The software provides real-time satellite tracking, pass predictions, and visual representations through Sky View, Earth View, and Timeline displays. It features an SDR-based waterfall display covering VHF/UHF satellite segments with Doppler-corrected frequency scales, automatic satellite labeling, and visual tuning capabilities. SkyRoof supports various SDR devices (Airspy Mini, SDRplay, RTL-SDR), external transceiver CAT control, and antenna rotator integration. The application automatically downloads satellite data from SatNOGS and other sources, offers voice announcements for satellite passes, and includes comprehensive frequency control with Doppler tracking, manual corrections, and RIT functionality for enhanced satellite communication operations.

Building an efficient antenna begins with selecting the right aluminum stock. This article provides a comprehensive guide to sourcing aluminum materials for antenna construction. It covers different aluminum grades, their tensile strengths, tempering options, and their suitability for various antenna components. The article also recommends reputable suppliers in the UK, making it a valuable resource for antenna builders seeking durable and high-performance materials.

The Ukrainian Contest Club (UCC) website details contest activities, including a March 2026 contest calendar compiled by _UW3WF_ that excludes specific "exotic" tests, mini-tests, sprints, VHF competitions, and events organized by Russian entities. It lists major contests such as the ARRL International DX Contest, Stew Perry Topband Contest, and CQ WPX SSB Contest, providing dates, times, modes, bands (e.g., **10-160m**), organizers, log submission methods, and deadlines. The resource also highlights Ukrainian participation in various international contests, noting specific callsigns that represented the UCC, and acknowledges new Ukrainian records, such as UW5Y's new record in the ARRL DX CW Contest. The site presents contest results and rankings, including the top 20 Ukrainian contesters in the World Amateur Radio Contesting Association (WARCA) rating for 2019-2024, with _UW1M_ ranked #18 globally and #1 in Ukraine with **26,490.32** points. It also details the club's 12th place finish among 155 clubs worldwide in the CQ WPX Contest 2024 (CW + SSB). The resource includes information on WRTC 2026 participants from the club and lists members excluded due to collaboration with adversarial entities, reflecting the current geopolitical context.

This project delves into the development of a compact WSPR beacon, building on earlier experiences with weak-signal modes. Inspired by QRP Labs kits and modified open source designs, it integrates a Si5351 frequency generator, GPS module, and class E PA for efficient operation. Extensive optimizations—addressing drift, heat management, and power stability culminated in a portable, serviceable device. The beacon offers insights into propagation while minimizing reliance on main station equipment. Lessons learned highlight the importance of careful component selection and iterative design improvements for robust amateur radio experimentation.

Home made free utility can be useful to monitor which is the RX and which is the TX VFO and the correspondig frequencies. Works with Yaesu FT-5000.

A vertical delta loop is a practical antenna for low bands, popular for its simple design requiring just one support. Its shape, an equilateral triangle in free space, yields optimal gain and radiation resistance. Deviating from this shape lowers performance. The delta loop can be polarized either horizontally or vertically based on the feed point location. In vertical polarization, it acts as two quarter-wave verticals with the baseline feeding one side. This design minimizes radiation from the baseline while maintaining effective operation.

Chokes and isolation transformers are essential for receiving antennas to mitigate common mode current, which induces noise and interferes with signal quality. Common mode chokes, formed by winding feedline through ferrite cores, block unwanted current effectively. Proper selection of core material and winding turns ensures resonance near the operating frequency, reducing interference. Isolation transformers further minimize interference, crucial for multi-transmitter stations.

This PDF document provides a design guide for a mini ununtenna, a popular antenna option among hams. It includes detailed instructions and specifications for constructing this type of antenna, making it useful for hams looking to build or optimize their antenna setup. The guide is intended for amateur radio operators with some technical knowledge and an interest in antenna design. It covers essential aspects of the mini ununtenna to help hams improve their radio communication capabilities.

The PA0FRI Unbalanced/Balanced ATU is a home-built antenna tuner designed to efficiently match a W8JK 2-element beam antenna fed with a 450-ohm twin lead. Based on PA0FRI’s S-Match design, it optimizes energy transfer while maintaining balance, reducing losses, and ensuring proper radiation. The tuner uses a roller inductor, air variable capacitors, and a T200 iron powder coil, allowing fine-tuning across 14-50 MHz. Extensive lab tests confirm minimal attenuation and precise impedance matching, making it a reliable and efficient ATU for balanced antennas.

A C-Pole Antenna for QRPxpeditions describes a DIY C-Pole antenna designed for QRP (low-power) expeditions, inspired by KF2YN’s ground-independent vertical model. After adjustments, it achieved a 1:1 SWR at 14.060 MHz, rising to 2.5:1 at 14.35 MHz. A choke balun, comprising 15 turns of RG8X around a 4” can, was essential for optimal performance. Compact and self-supporting, the antenna enables reliable communication with minimal setup. Contacts included stations across the U.S., and even a 4,600-mile connection to Spain using only 5 watts.

The Butternut HF2V, originally a two-band vertical antenna for 80m and 40m, was enhanced by the user to include 30m and 20m bands for better digimode DX work during the solar minimum. The additions used components adapted from the HF6V and innovative methods for the 20m addition, either through a parallel vertical element or a lower-mounted independent element, minimizing band interaction. This modified four-band antenna now supports high power across popular HF bands using a single feedpoint.

WB5NHL describes setting up a 160-meter antenna on a small suburban lot, where standard options like Beverage antennas and 1/4 wavelength verticals require extensive space and ground systems. Instead, Guy Olinger's Folded Counterpoise (FCP) provides a solution. The FCP minimizes ground losses by using a folded wire design, allowing effective antenna placement in limited space. The FCP, fed with an isolation transformer, enabled WB5NHL's first 160-meter antenna installation, offering improved performance despite space constraints.

The Shrunken Quad antenna is a unique design that offers full-sized performance on the 10m and 15m bands while incorporating linear loading via a trap for operation on the 20m band. This design allows for effective communication in the HF spectrum, making it suitable for both casual operators and serious DXers. The quad configuration provides excellent gain and directivity, which is beneficial for contesting and long-distance contacts. Constructing the Shrunken Quad involves careful attention to dimensions and materials to ensure optimal performance. The antenna's compact nature makes it an excellent choice for limited space situations, allowing operators to enjoy the benefits of a quad without the need for extensive real estate. This project is ideal for amateur radio enthusiasts looking to enhance their station's capabilities with a versatile and efficient antenna system.

This document outlines the construction of a homebrew Buddipole antenna variant, designed for portable use and emergency services. The antenna utilizes telescoping whips and loading coils, enhancing its versatility across various HF bands. Key components include fiberglass rods, brass fittings, and Anderson Power Pole connectors, ensuring robust electrical connections. The design emphasizes non-inductive materials to minimize interference, while practical assembly techniques, such as epoxy and heat shrink tubing, are employed for durability. This variant aims to improve upon traditional Buddipole designs, offering greater strength and functionality.

Analyzes the operational dynamics of the _IARU R1 VHF contest_, the world's largest 2-meter contest, focusing on factors enabling top performers to maintain consistent results amidst declining overall activity. The resource investigates the physical constraints that limit higher point totals, examining how technical capabilities, increased interference, and evolving station setups contribute to contest outcomes. It provides insights into the strategic and technical aspects of achieving high scores, such as the **1,000,000+ point** totals observed from leading stations. Compares the performance of various stations over time, highlighting the sustained success of top contenders and speculating on future trends in VHF contesting. The analysis delves into specific operational strategies and equipment choices that differentiate high-scoring stations, offering a detailed look at the competitive landscape. It also considers the impact of propagation conditions and operator skill on final scores, providing a comprehensive overview of the contest's intricate mechanics and the pursuit of maximum QSO points.

The Beverage on Ground (BOG) antenna offers ham radio operators a compact alternative to traditional Beverage antennas, requiring less space and fewer support structures. This implementation, optimized for 1.8-7 MHz bands, describes ideal parameters: lengths of 60-90 meters, height of 2-10 cm above ground, and specific load resistances based on configuration. The article details experimental methods for determining optimal load resistance and presents matching systems to convert BOG impedance to 50 ohms. While less effective than classic 200-300 meter Beverages, the BOG provides directional reception in limited space, though performance varies with ground conditions and weather changes.

A small windows utility to control VFO of the Yaesu FT-5000. It is capable to set frequencies for both VFOA abd VFOB. Tested with latest windows versions.

This document outlines various miniature projects undertaken by Mike Markowski to enhance his skills in GNU Radio. Key projects include an FM stereo receiver and an AM radio receiver, featuring advanced functionalities like pilot tone recovery and RDS integration. Additional experiments involve generating Gaussian noise, chirp signals, and Morse code decoding, emphasizing hands-on learning and customization in GNU Radio. The author encourages feedback and shares flow graphs and Python code for each project, aiming to foster community engagement and knowledge sharing.

This document provides comprehensive guidance on modeling and constructing multiband dipole antennas using traps. It addresses common segmentation issues in EZNEC modeling software, recommends optimal segment lengths for trap models, and compares trapped dipoles with paralleled multiband dipoles. While trap dipoles are significantly shorter, they exhibit lower gain and narrower bandwidth. Detailed instructions for building weatherproof coaxial traps include material lists, construction steps, and tuning methods. The guide notes that properly constructed coaxial traps introduce only minimal signal loss (0.6 dB) while offering practical multiband performance in a compact design.

The Communicator, a digital magazine by Surrey Amateur Radio Communications (SARC), offers over 125 pages of engaging amateur radio content. With contributions from regular columnists and minimal advertisements, it delivers practical articles, tips, news, and how-to guides for all levels of the hobby, reaching readers in over 165 countries.

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.

FT-240 toroids measurements. The data was measured using well-calibrated HP instrumentation. All plots have been adjusted to a frequency range of 1-100 MHz on the horizontal axis and a resistance/impedance range of 10-1,000 ohms on the vertical axis. This adjustment facilitates comparison among different materials and aids in determining their suitability for use on the HF ham bands.

When new to the 2-meter FM transceiver, securing a quiet frequency for chatter seems straightforward, but it's essential to navigate FCC rules and band plans effectively. Even though frequency allocations are consistent above 50 MHz for Technician licenses, adherence to specific segments within the 2m band—ranging from 144 MHz to 148 MHz—is crucial. This includes respecting designations for different modes like CW, SSB, and FM to prevent interference, particularly with satellites and exotic modes like EME. Understanding and following the structured band plans not only ensures legal compliance but also optimizes frequency use and minimizes disruptions in the amateur radio community.

Examining the demographic shifts within amateur radio, particularly concerning **radiosport** participation, this resource analyzes survey data from the National Contest Journal (NCJ) and two regional ARRL surveys. It focuses on the relationship between age and engagement in contesting, presenting findings that suggest older amateur radio operators tend to participate in more contests annually. The author, a spatial demographer, details the methodology, including data consolidation, georeferencing, and statistical analysis performed in collaboration with Dr. Scott Wright K0MD, covering ARRL November Sweepstakes participants from 2000 to 2020. The analysis also addresses the limitations inherent in using voluntary response samples rather than random samples, which may influence the generalizability of the results. Furthermore, the resource investigates the preferred sources of contest information among different age groups, noting that older contesters frequently rely on traditional publications like the NCJ, while younger participants show a preference for online platforms. This demographic review provides insights into the evolving landscape of **amateur radio contesting** and the generational differences in information consumption.

The multiband tuned doublet, or center-fed Zepp, is a simple and efficient HF antenna that operates effectively across most amateur bands using a balanced parallel-wire feedline and antenna tuner. Unlike coax-fed dipoles, it tolerates impedance mismatches with minimal loss. By selecting suitable feedline and dipole lengths, one can achieve stable multi-band operation. While it doesn’t match monoband Yagis, it offers excellent performance, low cost, and broad coverage. Its radiation pattern and efficiency vary with frequency, but it remains a practical and versatile solution for HF operators.

G6HKS Yagi Kits & Parts provides material kits for building high-performance PowAbeam Antennas, ideal for VHF/UHF enthusiasts interested in DXing. The kits feature advanced Yagi designs, including the unique ParAclip system, ensuring exceptional all-weather stability and minimizing detuning effects. With resources, tips, and support, the site aims to make antenna construction straightforward for amateur radio operators. The focus is on delivering top-tier performance at competitive prices, empowering users to build and enjoy their own high-quality antennas.

Chavdar Levkov, LZ1AQ, presents an experimental comparison of small wideband magnetic loops, building on his previous work on wideband active small magnetic loop antennas. His research focuses on increasing loop sensitivity by maximizing the short-circuit current, which is directly tied to the "loop factor" M = A/L, where A is the equivalent loop area and L is its inductance. Levkov's methodology involves reducing inductance and increasing area through parallel or coplanar crossed (CC) configurations, comparing these designs against a reference single quad loop of 1 m2 area. Experimental verification included testing three distinct loop types: a simple quad loop, two coplanar crossed (CC) loops, and eight parallel loops, all designed to have a total geometric area of 1 m2. Measurements were conducted at 1.8, 3.5, 7, and 10 MHz using a small transmitter 270 meters away, with a Perseus direct sampling receiver for precise signal level assessment. The results consistently showed that CC loops, particularly Loop 5 (two CC circular loops with 1.44 m2 total area), yielded significantly higher currents, up to 9.1 dB over the reference loop at 3.5 MHz, validating M as a reliable predictor of loop sensitivity. Numerical simulations using MMANA further corroborated the experimental findings, demonstrating an almost perfect correlation between the calculated M factor and the induced loop current for 15 different loop models. Levkov concludes that CC loops offer superior sensitivity for a given loop area, while parallel loops are advantageous for minimizing physical volume. Practical recommendations suggest using loops with an M factor greater than 0.5 uA/pT for quiet rural environments, and he provides a spreadsheet tool, WLoop_calc.xls, to aid in optimizing loop configurations for specific operational needs.

This tutorial demonstrates how to charge laptops or tablets, like the Microsoft Surface, using off-grid 12-volt batteries typically used for ham radio gear. The guide highlights the importance of selecting a reliable USB-C PD adapter, recommending a 15V, 60W minimum with 5–20V, 3–5A capability. Featured tools include a 100W USB-C adapter and a USB multimeter for monitoring power usage. The video also explores the compact, efficient Power Queen 50Ah LiFePO4 battery for portable power solutions.

The _DX EXPLORER_ blog serves as a personal chronicle of amateur radio experiences, particularly emphasizing homebrew projects and DIY radio equipment. It provides insights into constructing various transceivers and receivers, such as the Minimalist CW Transmitter and the Sputnik Regenerative Receiver, offering practical guidance for those new to the hobby. The content often details the assembly and operation of low-cost kits like the $3 Pixie Transceiver, demonstrating accessible entry points into radio construction. Beyond building, the site also features reviews of commercial gear, including the Tidradio TD-H8 Radio, providing an operator's perspective on performance and utility. The author, YO6DXE, shares a learning journey, aiming to inspire fellow enthusiasts to engage with the technical aspects of amateur radio. This resource covers a range of topics from basic circuit explanations to practical operating tips, fostering a deeper understanding of radio principles. The blog's focus on personal experimentation and project documentation makes it a relevant resource for hams interested in hands-on learning.

When installing a mobile antenna, optimal placement significantly impacts performance. Factors such as gain, antenna type, ground plane availability, mounting style, and environment must be considered. Antenna designs, such as 1/4 wave and 5/8 wave, have distinct radiation patterns ideal for specific settings—urban areas or flat terrains, respectively. Ground plane size requirements differ by frequency, impacting effectiveness. Among vehicle mounting options, the car roof center provides the best ground plane and minimal obstruction, ensuring peak performance, especially at higher frequencies like 800 MHz.

This page discusses the use of the new Version 4 RTL-SDR dongle for simple QRSS reception. The author shares their experience with connecting the dongle to a PA0RDT miniwhip antenna and using RTLSDRlop QRSS software. They encountered issues with Linux but found a solution with a new driver. The page also provides information on coupling multiple dongles to one antenna and adding selectivity with a divider-filter box. Hams interested in experimenting with RTL-SDR technology, antenna setups, and software for QRSS reception will find this content useful.

This project documents the construction of a coaxial 50 MHz notch filter to eliminate inter-band interference between 50 and 70 MHz transceivers. Using RG-213 coax and based on quarter-wave stubs, the filter achieved a 44 dB attenuation at 50.060 MHz while maintaining low insertion loss on 70 MHz. A dual-stub design broadened the notch response and minimized attenuation on 70 MHz to 0.2 dB. Fine-tuned using an FA-NWT network tester and Elecraft XG3 signal source, the filter effectively resolved interference for seamless dual-band operation.

The CW keyer with memories, inspired by SOTA activities, features three on-the-fly programmable memories for hands-free operation during logging or specific calls. Designed for low power consumption, it uses AAA batteries and an Arduino Mini, optimized for minimal energy use with a sleep function. The compact design fits in a small TEKO box, with a printed circuit board for easy assembly. The keyer includes customizable software for various CW modes and settings, programmable via paddles and command mode. It's an efficient, portable solution for amateur radio enthusiasts seeking enhanced CW functionality.

This software enables remote monitoring of the Kenwood TS-590SG HF transceiver. Based on a lightweight, text-based monitor was developed using Python and ncurses. It connects via rigctld, displaying key metrics like frequency, power, SWR, and TX/RX state with minimal data usage. Ideal for low-bandwidth remote operation, it works over SSH or mobile data. The software is open-source under GPL v3.

This project outlines a simple Lead Acid/SLA battery monitor, designed to alert users when battery voltage falls below 10.6V. The monitor, based on a PIC16F1827 microcontroller, checks the voltage of up to five batteries and triggers an alarm if any drop too low. The system operates in various modes, including self-test, monitoring, and alarm. This updated version improves upon the original 1999 design, offering a more modern microcontroller and extended functionality for workshop use, with minimal impact on battery charge.

KISS703 is a 703 Hz narrowband digital mode for amateur radio, designed for simple, low-power operation without computers. A 500 Hz pilot tone ensures frequency alignment, replaced by unique tones for 37 symbols (letters, numbers, space). Built from common discrete components, it draws about 40 mA at 12 V, ideal for SOTA/IOTA use. The receiver uses amplification, wave shaping, and a pulse-counting frequency meter for manual decoding via a calibrated meter. Transmitter and receiver calibration involves marking meter positions for each tone, enabling fully self-contained messaging with minimal hardware in portable or fixed operations.

Delta loop antennas, particularly the 30 meter variant, offer unique advantages in terms of vertical polarization and omni-directional coverage. The construction process detailed by VE3VN highlights common mechanical and electrical challenges faced by amateur radio operators. Key design considerations include minimizing interaction with existing contest band antennas, achieving low elevation angles for DX chasing, and ensuring the antenna remains off the ground for agricultural clearance. The article provides specific measurements, such as the loop's height and feed point impedance, which are critical for optimizing performance. The use of NEC modeling software illustrates the importance of accurate resonance calculations, revealing how proximity to the tower affects both pattern and impedance. This practical account serves as a resource for hams looking to build effective antennas while navigating typical construction hurdles.

This comprehensive article dispels common misconceptions about Standing Wave Ratio (SWR) in amateur radio. The author explains that SWR is not an antenna property but a measure of the entire antenna system, representing the mismatch between transmission line and load impedance. Contrary to popular belief, modest SWR values (under 3:1) typically cause minimal power loss in HF applications. The article demonstrates mathematically why obsession with achieving 1:1 SWR is often unnecessary, explains when SWR matters more (QRO, QRP, VHF/UHF), and explores effective matching techniques including proper ATU placement and quarter-wavelength transformers.

This page details the construction of an ATU-100 (N7DDC) automatic antenna tuner. It provides a photographic build log from the arrival of parts to the final assembly, including winding the tandem match and connecting the OLED display and optional control buttons. The author discusses modifying the EEPROM for QRP operation by setting the minimum tuning power to 1 Watt. Key components shown include the SWR bridge, relays, and the custom case made from a Macbook Pro cover. The article references external GitHub pages for full information, R0AEK's pages for helpful details, and a video by MW0SAW regarding EEPROM settings for different ATU-100 variants. The build focuses on practical steps and includes tips like modifying RG58 strands for PCB fit and adding capacitors to button connections to prevent RF interference with the CPU. The author plans further testing during SOTA or portable activities.

This article details the design and construction of a compact 20-meter QRP SSB transceiver by Pete Juliano, N6QW, measuring just 2 x 4 x 2 inches—small enough for a shirt pocket. Inspired by a 1963 QST design and refined from a prior version, it employs bilateral circuits, a 4.9152 MHz homebrew crystal filter, switched-crystal VXO for 60 kHz coverage (14.160-14.220 MHz), and standard components like ADE-1L mixers and IRF510 PA for 1W output. Key innovations include a double-sided PCB skeletal frame for shielding and isolation, Vectorboard sub-assemblies, and ultra-miniature relays. The bilateral receiver/transmitter shares stages, omitting AGC for simplicity, while a W3NQN LPF and optional 10W external amp enable DX contacts. Tune-up focuses on crystal matching and bias for linearity. Videos on YouTube demonstrate performance, confirming excellent stability and audio. Total cost nears $100, prioritizing portability over features like CW.

This page by ARCTICPEAK provides a calculator for determining ERP and EIRP (Effective radiated power and effective isotropic radiated power). The tool is designed to help hams calculate and understand the power radiated by their radio equipment. The content is useful for ham radio operators who want to optimize their transmission power and comply with regulations. LA8OKA Martin has created this resource to assist hams in accurately measuring their radio signals.

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.

Antenna project for a home made quagi antenna for UHF Bands, 432 MHz. This projects is done using some aluminium bar rods and includes design and pictures of the project

The article discusses the construction of a UHF band-stop stub filter to protect an APRS receiver from potential damage during a balloon launch. The author, who communicates using a 441 MHz transmitter, needed to ensure that the RTL-SDR dongle receiving at 144 MHz wouldn't be damaged by the transmissions. The solution involved creating a quarter-wavelength open stub filter using coaxial cable, which attenuates the 441 MHz signal while allowing the 144 MHz signal to pass through. The filter's design is based on the principles of constructive and destructive interference, with careful measurement and trimming to achieve the desired frequency response. The final filter provided 34.8 dB of insertion loss at 441 MHz and minimal loss at 144 MHz, effectively protecting the receiver.

The LKJ Wednesday Night Special Antenna, designed by John Whiteman K5LKJ, is a compact 50-foot coil-loaded dipole for 80-meter operation, ideal for space-limited hams in residential areas. Using two 1-inch diameter PVC coils with 87 turns of #16 magnet wire each—placed 10 feet from the center—it tunes to 3.910 MHz for local nets like BVARC Rag Chew. Constructed with #14 wire, ceramic insulators, and Mini-8X feedline, it handles 1000W, performs well at low heights for NVIS, and requires a tuner for bandwidth. Collaborative tuning by club members ensured success.