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The W5GI Mystery Antenna is a versatile multi-band wire antenna designed for amateur radio operators. It covers frequencies from 80 meters to 6 meters, making it suitable for a wide range of operating conditions. The antenna features a low feed point impedance, allowing for easy matching with most radios, whether or not an antenna tuner is used. Its construction is straightforward, requiring only two vertical supports approximately 130 feet apart, making it ideal for hams without towers. Users have reported excellent performance, particularly on the 20-meter band, where it outperforms similar designs like the G5RV. This antenna is unique in its design, incorporating three half waves in-phase on 20 meters, resulting in a six-lobe radiation pattern. Despite its effective performance, the antenna is challenging to model, which adds to its mystique. The W5GI Mystery Antenna has gained popularity among amateur radio enthusiasts worldwide, with many users praising its ease of construction and effectiveness. Whether you're a beginner or an experienced operator, this antenna offers a fun and rewarding project that can enhance your HF capabilities.

Presents the KE4UYP linear-loaded vertical antenna design, which introduces very little loss on 80 or 160 meters, achieving an overall radiation efficiency of 80% to 85%. This design addresses common pitfalls of traditional base-fed verticals by placing the majority of the current at the top of the antenna, eliminating the heavy reliance on extensive ground radial systems. The author's initial 10-meter model, only three feet tall, yielded 5/9 signal reports to Anchorage, AK, and Europe, confirming its effectiveness. The antenna incorporates both vertically and horizontally polarized radiators, with a 1/4 wavelength horizontal counterpoise located at the feed-point, near the top, to create an almost totally omnidirectional pattern with high wave angle horizontally polarized radiation. This dual polarization ensures even illumination across all take-off angles, making it effective for both local contacts and **DXing**. The vertical element is linear loaded, adding capacitance reactance and making it longer than the horizontal element to achieve resonance and raise the feed-point impedance to 50 ohms. Fine-tuning the antenna requires careful adjustment, as tower reactance can vary. The article suggests starting with 80 feet for 80m and 170 feet for 160m for the vertical wire, then trimming for resonance. Bandwidth specifications include 300 kHz under 2:1 **SWR** on 80m and 100 kHz on 160m when suspended between trees, or 150 kHz on 80m when side-mounted on a tower.

This project details three variants of a vertical half-wave antenna design for the 4-meter (70MHz) amateur radio band. The antennas use end-feeding with a parallel-tuned circuit for impedance matching to 50-ohm coaxial cable. The first variant uses suspended flexible wire for portable use, the second employs a fiberglass rod with internal wire for permanent outdoor installation, and the third utilizes aluminum tent poles for quick mobile deployment. Despite the narrow bandwidth of the matching circuit, this suits the narrow 4m FM allocation well. The design offers an effective omnidirectional radiation pattern and can be constructed with readily available materials.

This Multiband Cubical Quad antenna a boomless Quad design with glass-fibre arms and a single coax wire connected to a remote antenna switch. This aerial work on 8 bands and has a 60-degree beam width. Despite achieving critical technical requirements, the antenna's three-dimensional structure presents obstacles, such as installation issues on fixed towers and risk of frost damage. The spider framework is built of stainless steel, with a compact 18-inch boom and strong angle iron arms. Tait use a variety of methods to fasten element wires and suggests placing them on the outside of the spreaders for improved insulation. The use of nylon twine or parachute cord between key attachment points allows for adjustable separation between pieces.

A three element wire yagi antenna for 7 MHz project plan with drawings and EZNEC model

GW4ALG's _136 kHz Pages_ document the evolution of vertical antennas for the 2200m band, starting with a prototype mounted on a house wall. This initial design, despite achieving the first **395 km** GM-GW QSO, suffered from significant insulation breakdown, high RF losses due to proximity to the house, and difficult tuning adjustments. The author details the challenges of maintaining resonance and matching with a variometer in the loft, noting that adding three earth spikes offered no measurable improvement over a simple water tap connection. The subsequent experimental 12m vertical, relocated away from the house, significantly reduced dielectric losses and proved far more effective. This antenna enabled GW4ALG to set a world DX record on 136 kHz with a **1916 km** QSO to OH1TN, and an intra-UK record of **703 km** to GM3YXM/P. The resource further explores the use of helium-filled balloons to extend the vertical radiator, achieving heights up to 27m, typically 20m, for enhanced low-band performance. Practical advice on balloon types, inflation, and critical insulation between the wire and balloon is provided, emphasizing safety and avoiding arcing.

The G5RV multiband HF antenna, designed by Louis Varney (G5RV) in 1946, is a popular compromise antenna offering good overall performance on most HF bands when paired with an external antenna tuner. The basic full-size G5RV measures 102 feet across the top for 80 through 10 meter operation and is fed at the center via a 34-foot low-loss feed-stub. This interaction between the radiating section and the feed-stub facilitates matching across 80-10 meters with a standard tuner, often eliminating the need for ladder line directly to the shack. The antenna's design center frequency is 14.150 MHz, configured as a 3/2-wave dipole on 20 meters, with its 102-foot length derived from long-wire antenna formulas. Construction details emphasize the matching section, which can be open wire, ladder line (window-type), or TV twin lead. Each type has a specific velocity factor (VF) affecting its physical length for an electrical half-wave on 14 MHz; for instance, open wire requires 33.7 feet (VF 0.97), ladder line 31.3 feet (VF 0.90), and TV twin lead 28.5 feet (VF 0.82). The article provides formulas for calculating these lengths and discusses the antenna's behavior on individual bands, from 3.5 MHz where it acts as a shortened dipole, to 28 MHz where it functions as two three-half-wave long-wire antennas fed in-phase. Practical construction notes include recommendations for vertical descent of the matching section, sealing the coax junction, providing strain relief, and winding a coaxial choke coil to mitigate common mode current. The resource also presents dimensions for double-size (204 ft) and half-size (51 ft) G5RV versions, along with their corresponding matching section lengths for various line types, making it a versatile reference for hams considering this classic wire antenna.

This article describes the details of the design, which can be easily scaled for just about any HF band. The antenna described in this article is for the 20 meters band.

A 102-inch vertical whip, commonly a CB antenna, forms the core of this low-profile 10-meter antenna design, optimized for the 28 MHz band. The construction details specify three 8-foot radials made from scrap wire, connected to a common point. This simple yet effective setup is designed for ease of construction and deployment, making it accessible for operators with limited space or materials. The design emphasizes using readily available components, including PVC pipe for the mast and a SO-239 connector for the feedline, ensuring a straightforward build process for a resonant quarter-wave vertical. Field results indicate that this antenna provides good performance for local and DX contacts on 10 meters, despite its compact footprint. The author, N8WRL, shares practical insights into its construction and tuning, highlighting its suitability for temporary or permanent installations where a full-sized antenna might be impractical. Comparisons to more complex designs suggest that this low-profile vertical offers a respectable signal-to-noise ratio and effective radiated power for its size, proving that simple designs can yield satisfying on-air results.

K1JJ presents a compilation of insights regarding vertical radial ground systems, specifically applied to 160m vertical arrays. The resource details 19 distinct observations and recommendations, emphasizing that ground radials primarily reduce ground losses rather than influencing pattern formation. It explains that RF current flows inefficiently through average soil, necessitating copper radials to create a low-resistance path back to the antenna base. The content suggests that **50-60 radials** are generally sufficient to achieve optimal efficiency, with diminishing returns beyond that number, and that radials should be laid on the surface for best performance. The discussion also addresses practical aspects such as wire gauge, installation techniques using 'U' shaped staples, and methods for connecting radials in multi-element arrays. It highlights the importance of radial length, stating that 1/4 wave radials are a crucial minimum, and that for 160m, radials should be at least _100 feet_ long. The resource critically examines the efficacy of elevated radials versus ground radials, noting that while a few elevated radials may suffice for VHF, HF applications, particularly on 160m, require extensive ground radial systems to efficiently collect RF currents in the near field. It also touches on the impact of radial systems on parasitic elements and the significance of symmetrical radial patterns for minimizing losses. Further practical advice includes wire type recommendations, proper soldering and weatherproofing techniques for radial connections, and considerations for integrating steel towers into the ground system. The author shares personal experience with installing 60 quarter-wave and half-wave radials under each of three in-line verticals, expressing satisfaction with the results.

This antenna is designed for stations having a difficult time putting a decent signal on 160M from small or CC&R d lots. It is a 24.5 ft. vertical antenna, made from three 10 ft. PVC sections bolted together, and half wavelength of antenna wire helically wound around the PVC sections.

On December 12, 1901, Guglielmo Marconi successfully received the first transatlantic wireless communication, a Morse code "S" (three dots), at 04:30 GMT. This article details the setup for this groundbreaking experiment, noting Marconi's receiver in St. John’s, Newfoundland, Canada, utilized a _coherer_ and an antenna elevated by balloons and kites. The transmitting station at Poldhu, Cornwall, England, featured twenty-four 200-foot ships' masts and a 25-kilowatt alternator. The resource explains how this contact disproved contemporary beliefs about radio wave limitations due to Earth's curvature, later understood through _ionospheric propagation_. It frames Marconi's achievement as the "very first DX" in amateur radio terms, defining DX as telegraphic shorthand for distance and _DXing_ as the hobby of receiving distant signals. The article also provides external links for further reading on Marconi's experiments and the science behind transatlantic radio signal reception.

This article describes the construction of a three-band vertical antenna for the WARC bands (10, 18, and 24.9 MHz). Unlike a previous design using thin wire requiring a complex matching device, this version uses a telescopic set of pipes, reducing reactances and simplifying the matching device to two coils and two capacitors. The article provides details on the antenna model, the matching device circuit, and tuning methods, including the use of frameless coils and variable capacitors. With proper tuning, the antenna achieves a VSWR not exceeding 1.3 across all bands, demonstrating a practical and efficient design for amateur radio enthusiasts.

This comprehensive three-part guide examines baluns (balanced-to-unbalanced devices) and their critical role in ham radio antenna systems. The author explains how baluns prevent common-mode currents on feedlines, which can distort radiation patterns and cause unwanted RF in the shack. Various balun types are analyzed, including coiled coax chokes, ferrite-core designs (W2DU), and toroidal-wound versions (Guanella/Ruthroff). Construction techniques for 1:1, 4:1, 6:1, and 9:1 current baluns are provided with practical guidance on wire selection, winding methods, and ferrite core properties. The article emphasizes that proper balun implementation is essential for optimal antenna performance, especially with directional arrays.

W1JR-style common mode chokes are versatile tools for antenna experimentation. Three variants were constructed using RK4 ferrite cores and RG303 Teflon coax, differing only in output terminals: banana connectors for dipoles, N-connectors for antennas with existing terminals, and bolts with washers for vertical antennas. Materials included junction boxes, terminals, and small hardware. Assembly involves maximizing windings on the core, securing with ties, and gluing components. Improvements included switching to multi-stranded wire for durability. These chokes provide efficient, customizable solutions for various antenna setups.