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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.

This article loaded with nice pictures and schematics, describes a 160-10 meter linear amplifier that uses a pair of 3-500Z triode power tubes. It was designed and constructed by William Moneysmith, W4NFR. The amplifier features fast warm up and 1500-Watt RF output with 100-Watts of drive.

An homebrew project for a 3 element coil-loaded Yagi beam antenna for 40 Meter band

Homemade Loaded Coil Dipole ( w8010 diamond ) for 10, 15, 20, 40 and 80 meter

In this article the author describes some new designs of ferrite loaded chokes for suppressing unwanted common mode currents at HF applied to feed lines like choke baluns, but also in the shack, applied to various coaxial, mains and data cables

Antenna for limited space, made from 24AWG wire helically wrapped around the top element of a 3-element cane pole, is basically a fully-loaded vertical and performance are limited and should represent the last resort for extreme cases.

The 60-page PDF document, "Antenna Systems and Theory For The Non-Technical Ham" by Jim Abercrombie, N4JA, provides a foundational understanding of antenna systems. It explains basic antenna theory, including how antennas work, electromagnetic wave polarization, and the role of frequency. The resource details various antenna types such as flat top dipoles, inverted-V dipoles, shortened loaded dipoles, G5RV dipoles, Carolina Windoms, and end-fed configurations. Vertical antennas, including ground-mounted trapped verticals and inverted-L verticals, are also covered. Directional beam antennas like monoband Yagis, cubical quads, and log-periodic arrays are discussed. Propagation modes, including ground-wave, direct wave, and skywave propagation, are explained in detail, with specific attention to the D, E, and F layers of the ionosphere and their effects on HF communication. Technical concepts such as standing wave ratio, decibels, resistance, and reactance are defined, along with calculations for half-wave resonant dipole lengths. The document addresses feed-line radiation, balun applications, and critical antenna and tower safety considerations. It aims to dispel common antenna myths and educate hams on making informed antenna choices.

A small dipole antenna installed inside a balcony. This linear loaded short dipole antenna has been designed at first for the 21 MHz and then adapted for the 20 meters band.

Amateur Radio 40m 20m 15m Half Wave Fan dipole antenna project with part list, pictures and drawing. Includes the option to expand the antenna to cover the 80 meters band

Performance of an unloaded ground mounted vertical as a multi-band HF antenna.

A free photo hosting service for amateur radio. Upload your own photos or browse through what others have uploaded.

A considerably shortened Magnetic Loop antenna with performance of a single conductor text book magnetic loop.

The OZ1CX center-loaded mobile antenna project details the construction of a compact **80-meter** antenna, specifically designed for mobile, portable, and stationary operations. It features a loading coil wound on a 50 mm PVC pipe with 1.5 mm copper wire, comprising 100 turns over 150 mm length, resulting in an inductance of 150 µH. The design incorporates a 1.5-meter whip and a 1.5-meter base section, with the coil positioned at the center for optimal performance on the 3.5 MHz band. Performance measurements indicate a **VSWR** of 1:1.2 at 3.7 MHz when mounted on a vehicle, achieving a bandwidth of 30 kHz for VSWR below 1:2. The antenna's efficiency is compared to a full-size dipole, showing a signal strength reduction of 3-4 S-units, which is typical for compact mobile HF antennas. Practical application notes cover tuning adjustments by varying the whip length and coil tap points, emphasizing the importance of a good ground plane for effective operation.

A dual band dipole antenna for 40 and 80 meters band. Total lenght of 26 meters, foreseen two coils at aprox 11 meters distance from center feed.

A simple dipole for 40m band feeded with 450-Ohm openwire feedline includes MMANA Gal files to download

Complete collection of the four main parts of this excellet research on modelling and designing half wave dipole antennas for 40 meters band, covering all aspects beginning from full wave length antennas, to shortened, loaded and reshaped dipoles

Simulation of a top loaded vertical antenna for 1.2 MHz

Experimenting a 20 40 meter short coil loaded dipole antenna with the goal to keep the total length under 40 feet so that the dipole can be mounted on two 20 foot fiberglass pole to make a 20/40 meter rotatable dipole.

The Alcorn County ARES group provides crucial **emergency communications** support within Alcorn County, Mississippi, operating under the Amateur Radio Emergency Service framework. This organization mobilizes licensed amateur radio operators to assist public safety agencies during emergencies, natural disasters, and other critical events when conventional communication infrastructure fails or becomes overloaded. Their activities include regular training exercises, participation in local drills, and maintaining readiness to deploy communication assets. Members engage in various aspects of amateur radio, including voice, digital modes, and message handling, ensuring a robust and redundant communication network. The group's focus on preparedness and community service aligns with the core principles of ARES, emphasizing rapid response and effective information relay during crises. They often collaborate with local emergency management agencies, such as the Alcorn County Emergency Management Agency, to integrate amateur radio capabilities into broader disaster response plans. Dustin Brumfield, KD5LAP, serves as the Public Information Officer, facilitating outreach and coordination. The club's operational area is specifically Alcorn County, Mississippi, contributing to local resilience.

A multi band antenna for HF band capable to operate from 10 to 80 meters band depending on wire lenght loaded with a small inductance neat the feed end.

TLV80 is model of a Top Loaded Vertical Antenna is doing a good job for DX on 80 m band. A version for 80m-30m is provided.

Visualizing DXCC award progress often requires manual parsing of Logbook of the World (LoTW) reports, which can be time-consuming and prone to error. This web-based utility streamlines the process by allowing hams to upload their LoTW DXCC Credit Report spreadsheet, providing an interactive dashboard for tracking confirmed entities, bands, and modes. It processes .xlsx, .xls, and .csv files, performing all calculations client-side within the browser for privacy and speed. The tool presents a comprehensive stats overview, detailing total entities, confirmed slots, and overall completion percentage. It includes progress bars for bands from _160m_ through _2m_, and modes such as CW, Phone, and DIG. A sortable DXCC Entity Details Table lists each entity, its confirmed count, and specific missing band/mode slots, with a CSV export option. Further features include a Band/Mode Matrix grid for granular confirmed status per entity, toggles for specific bands like _6m_ and _2m_, and tracking for DXCC Challenge progress across 10 eligible HF/VHF bands. It also highlights nearly complete entities and identifies most-wanted DXCC entities based on the uploaded data.

Gimme Five reloaded, a compact 5 band QRP SSB transceiver in SMD technology. This unit covers 5 bands within the amateur radio spectrum (3.5, 7, 14, 21 and 28 MHz). Receiver is a single conversion unit with an interfrequency of 9 MHz. Transmitter uses 5 stages and has got a power level of 10 watts PEP output.

Top Loaded Vertical Antenna 3,5 MHz 80m and a 14 MHz Trap for the 20m band. The weight of this portable vertical antenna is less than 1 kg, including the ground network. The weight of the telescopic fiberglass fishing rod is another 1kg. The rod expands from 1.5 meters to 8 meters.

A 60-foot available space, for example, might necessitate a shortened multiband dipole array to cover 80, 40, and 15 meters effectively. This resource details the construction of such an antenna, combining full-size and coil-loaded dipoles on a single feedline. It addresses the common challenge of fitting multiple HF bands into restricted physical footprints, providing practical guidance for hams with smaller backyards or portable operations. The core of the offering is an interactive calculator that determines required loading coil inductance and dipole lengths for various amateur bands from 160m to 10m. Users input their available space, and the tool provides dimensions, coil turns, and an efficiency rating (Good or Fair) based on the antenna's electrical length relative to a quarter-wavelength. It also suggests suitable _PVC_ pipe diameters for coil forms. The article further illustrates a center feed-point assembly using an 18-inch section of 2-inch _PVC_ pipe, detailing eye-bolt spacing and coaxial connector installation. It emphasizes the importance of adequate spacing between parallel dipoles and offers customization options for the feed-point, including the addition of a _Balun_ for improved feedline isolation.

This article demonstrate how to build and mount a 40 meter loaded dipole using basic materials. This antenna reduce the overall length of an HF dipole through the use of loading coils.

All available frequencies & offsets configurations for repeaters can be downloaded as database for Kenwood MCP-2A memory channel programming software for TM-D710 & TM-V71. Zip file is no more available from the author, but the full table of frequencies is still online

This antenna just requires about 24m of free space instead of 41m that a normal half wave 80m antenna needs to hang up. The so called loaded dipole uses a coil in every dipole arm to electrically lengthen the mechanical too short dipole arms. Every coil has an inductivity of 120 microHenry.

This article shares the author's experience with building antennas. After putting a large magnetic loop project on hold, they decided to try a base-loaded vertical antenna. The author explains how they chose to design a new antenna from scratch, aiming for a frequency of 7 MHz. They describe the calculations needed to find the right coil inductance and how they used 3D-printed parts for the construction. The article wraps up with results from their initial tests, showing good communication on different bands and highlighting the success of their design.

Accessing current operational statistics for a DXpedition is crucial for DXers planning their next contact. This Club Log page provides a detailed, real-time overview of the 3Y0J Bouvet Island operation, a highly sought-after DXCC entity. It presents a dynamic dashboard showing total QSOs, unique calls worked, and duplicate contacts, all updated as logs are uploaded from the remote location. Users can observe the expedition's progress and strategize their operating times. The interface features interactive charts and graphs, allowing operators to analyze the _3Y0J_ log data by band and mode, including CW, FT8, and SSB. A breakdown of QSOs by continent provides insight into propagation patterns and where the expedition has focused its efforts. The page also includes a map for checking real-time propagation conditions to Bouvet Island, which is invaluable for optimizing contact attempts. Further details include the first and last QSO times, total operating days, and the impact on users' DXCC totals, such as new bands, modes, or DXCC entities worked. This resource is a vital tool for the DX community, offering transparency and actionable intelligence for chasing one of the rarest entities on the air.

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

Here is a formula and calculator for creating a loaded (shortened) quarter wave vertical or balanced dipole. The calculation refers to either a loaded 1/4 wave or a loaded dipole

Experimentin wire antennas on top band using several type of aerials. This includes a 40 to 160 meters EndFed Half Wave kite antennas and 160m/80m loaded vertical antenna.

This blog chronicles the development of an 80-meter vertical antenna for amateur radio operation. The author constructs a top-loaded vertical using fiberglass poles, achieving significant performance improvements over their previous end-fed wire antenna. Comparative testing using the Reverse Beacon Network and on-air contacts demonstrates 8-10 dB gain on the east coast. The project evolved to include 40-meter capability through a modified design featuring a four-wire vertical cage, loading coil, and strategic guying system. Despite challenges with signal wobble during windy conditions, the vertical consistently outperforms the end-fed wire, particularly for reaching distant stations during nighttime propagation.

Dipole for 40m band. It is a simple linear loaded dipole feeded with 450-Ohm openwire feedline. Designed it for resonance at 7.050 MHz, can be tuned on 30m and 80m bands with an external antenna tuner. Build with simple electrical copper wire (2.5 mmq/13 awg) and two fishing poles with size of about 7 m/23 ft.

Presents an interactive **Ham Bands Explorer** web application, offering a live view of all amateur radio bands overlaid on a world map. This resource displays **CQ zones** and **ITU zones**, with geographical data sourced from HB9HIL/hamradio-zones-geojson under an MIT license. The interface provides a dynamic visualization of global band conditions, enabling operators to observe activity patterns across different regions. Users can select individual countries to retrieve and display their specific band plans, with frequency coverage details loaded from CountryData.json. The tool indicates 100% frequency coverage, ensuring comprehensive data presentation for selected regions. This functionality supports detailed analysis of national regulatory variations within the amateur spectrum. The application integrates both a map view and a live view, facilitating real-time monitoring and geographical context for band usage. It serves as a practical reference for understanding international amateur radio regulations and visualizing propagation characteristics across various frequency allocations.

80m Inverted-L Antenna, Base-loaded for 160m antenna. This antenna is not a good DX antenna however within small garden where true DX antennas would be impossible it has performed very well.

Cavity is often required at a busy site to not only prevent its receiver from being overloaded by off-frequency signals, but also be a good neighbour and prevent low-level signals from your transmitter from getting into other users receivers - not to mention the preventing of those other signal from getting back into your transmitter to generate spurious signals in its own right.

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.

Documents the A35EU DXpedition to Tonga, specifically targeting the _IOTA OC-049_ Tongatapu group during 2018. The resource outlines the operational bands from 10 to 160 meters and the primary modes utilized, including _CW_, _SSB_, RTTY, and FT8. It provides essential information for DXers interested in confirming contacts with this rare entity, detailing the logistical aspects of the operation and the specific island group activated. This page serves as an archive for the A35EU operation, offering QSL update information and confirming that all log queries were processed and a fresh log uploaded to _Clublog_. Such details are crucial for operators seeking to verify their contacts and apply for awards like DXCC or IOTA, providing a definitive record of the expedition's activity and post-operation administrative status.

The project details the construction of a portable multiband mobile antenna, designed for rapid deployment with an _Elecraft KX3_ for /M operations. It utilizes a coil and the car body as a counterpoise, enabling operation across multiple HF bands. The article presents a table of coil tap positions for 40m, 20m, 17m, 15m, and 10m, along with corresponding SWR measurements, demonstrating an SWR below 1.5:1 on all tested bands. Photographs illustrate the antenna's components, including the coil winding and mounting mechanism, and its deployment on a vehicle. The author provides insights into the antenna's performance characteristics, noting its resemblance to a vertical dipole despite the unconventional ground plane. The resource includes a parts list and construction steps, making it reproducible for other radio amateurs.

TNXQSO.com offers a streamlined **log search** utility, specifically designed to consolidate QSL information for **DXpeditions** and special event stations. This online service aggregates data from prominent logging platforms such as Club Log, Logbook of The World (LoTW), and HRDLog, presenting a unified interface for radio amateurs to verify their contacts. The platform aims to simplify the process of confirming QSOs by providing direct links to the respective logging services, allowing users to quickly ascertain if their contact has been uploaded and confirmed. Users can input a callsign and band to retrieve immediate results, indicating whether a QSO is present in the linked logs. The service also supports DXpedition teams by offering tools for managing their own logs and QSL routes, without requiring an account for general log searching. This functionality proves particularly useful for DXers seeking rapid confirmation of rare contacts or for those managing their QSLing efforts across multiple platforms after a significant operating event.

The _Amateur Radio Logbook ADIF File Analyzer_ processes ADIF files locally within the user's browser, ensuring no QSO data is uploaded to a server. It generates a visual map of contacts and detailed statistics across various parameters, including band, mode, time, grid squares, and DXCC entities. The tool offers insights into operating patterns and station performance without requiring any software installation. Users upload their ADIF log files directly, and the analysis is performed client-side, providing immediate results. The output includes charts and graphs that visualize QSO distribution and activity. This approach prioritizes user privacy and data security, as logbook information remains on the user's computer throughout the analysis process. The analyzer supports standard ADIF formats, enabling hams to quickly review their log data for trends and achievements. It is a free, open-source utility designed for general amateur radio log analysis.

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.

This page discusses the CLEFHW (Coil Loaded End-Fed Half-Wave) antenna, a portable variation of the popular EFHW design for ham radio operators. The article explains how the CLEFHW allows for backpack portable operation without the need for trees or poles, making it ideal for POTA activations and rapid deployment scenarios. The author details the design, optimization for 20m band, and compares efficiency to full-length wire antennas. Suitable for hams interested in portable antenna solutions and quick setup options for amateur radio activities.

This page discusses the construction and design of a shortened 2-element Yagi antenna for the 40-meter band, focusing on the driven element. The author shares insights on adding hats to the coil to reduce losses and improve performance. The article also mentions the use of EZNEC modeling software and an AIM4170 analyzer for tuning. Amateur radio operators interested in such antenna design and optimization for the 40-meter band can find useful information and practical tips on this page.

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.

SKY Audio is a duplex remote audio software for Windows, allowing two-way audio transmission between devices. Users can send and receive audio, as well as engage in PTT functionality. The program offers low audio latency and the ability to configure connection settings. The freeware software can be downloaded from the provided link.

EU-DX Propagation Coach v0.9.3 processes live _Reverse Beacon Network_ (RBN) spot data, providing practical DX propagation guidance for European radio amateurs. The software offers a real-time RBN-based propagation overview, including directional guidance, enabling users to optimize band usage based on current conditions. It features five selectable European station locations and ten global DX reference centers, delivering propagation scoring for the 10, 15, and 20-meter bands, alongside a 40/80-meter overview. Dynamic azimuth and reverse-path information are calculated for each DX direction, assisting operators in precise antenna aiming. The application is distributed as a Windows ZIP archive, requiring full extraction before execution. A SHA-256 hash is provided for download integrity verification, ensuring the downloaded file matches the original. Users should note the software is provided "AS IS," and DL6UAA disclaims liability for any resulting damage or data loss. The tool is designed to run on Windows platforms, offering a dedicated utility for real-time propagation analysis.

This online tool is a specialized web-based utility for orchestrating multi-operator HF contest and DXpedition activities. This tool, _Rig2Cast_, assists station managers in meticulously planning operator shifts, ensuring adequate rest periods, and crucially, preventing operational conflicts such as assigning a single operator to multiple radios concurrently. It integrates support for SO2R operations and offers real-time simulation of operator requirements, a feature I've found invaluable in pre-event planning. The scheduling engine incorporates five distinct algorithms: greedy fairness balancing, round robin, maximum coverage, simulated annealing, and a fatigue-aware model. These algorithms enforce critical constraints like minimum/maximum shift durations and mandatory rest times across all radios, which directly impacts operator performance over long events. My field experience confirms that such robust constraint management is essential for maintaining peak efficiency during intense operations. Key features include distributed multi-station support, printable per-operator cards, flexible band activity windows, and real-time editable operator slots. The drag-and-drop shift management, coupled with full cross-radio swap support and smart constraint feedback (valid targets in green, invalid in red), streamlines complex scheduling tasks. The system's design ensures user data privacy, as no information is stored on the server; schedules are saved and reloaded locally.