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The 30/40 meter **vertical antenna** project by IK4DCS details the construction of a shortened, self-supporting design, reaching a total length of 5 meters. The antenna incorporates a linear loading section and a coaxial cable trap for 30 meters, based on the "Antenne Volume 2°" text by Nerio Neri (page 223). The design uses six radials, three for each band, positioned at approximately 90° inclination and at least one meter above the roof or ground, connected via a 1:1 balun at the feed point. Mechanical construction utilizes aluminum tubing, with a 2.30-meter primary radiator section (30 mm diameter) joined to a second part using a Teflon insert and a PVC sleeve for rigidity. The linear load, approximately 3.70 meters long, accounts for a 30% physical shortening of the quarter-wave element. A capacitive load, made from three 50 cm radials, is integrated into the 40-meter top section for fine-tuning. Final adjustments involved radial inclination for 40 meters, as initial testing showed increased SWR and interference on 30 meters due to nearby resonant structures. The author emphasizes the importance of clear space for optimal performance and provides drawings and photos to clarify the build process.

This article refers mainly to the old Cushcraft 1/4 wavelength AV series of antennas (12AVQ, 14AVQ etc) hence the references to radials. The R series (R5, R7 etc) are 1/2 wavelength antennas, and the radials are NOT 1/4 wavelength resonant.

This resource details the conversion of an 80m elevated vertical antenna to include 160m operation, focusing on a relay-switched design over a trap-based approach. It presents specific feedpoint impedance values, such as **32 ohms** for 80m and **14 ohms** for 160m, and discusses the challenges of SWR drift encountered with the prior trap system during RTTY contesting. The article thoroughly explains the design choices for elevated radials, referencing _N6LF QEX data_ to debunk common myths regarding radial length and height, demonstrating that non-resonant radials can offer superior current uniformity. The construction section provides practical insights into building the vertical, including guying strategies, material selection from scrap pipe, and weatherproofing the relay assembly. It highlights the use of a common mode choke for the relay switching line, measuring approximately 5K ohms on both 160m and 80m, and details the L/C matching network's role in achieving a 50-ohm match at the end of a 300-foot RG-11 run. The author describes a precise VNA-based radial trimming procedure, achieving resonant values within a 3 KHz range. The content emphasizes the practical application of theoretical antenna principles, particularly concerning the interaction between the vertical element, cap hats, and the matching network. It offers a candid assessment of component selection, such as using junkbox parts and acknowledging the need for future upgrades to static drain resistors. The article serves as a comprehensive case study for advanced antenna builders tackling multi-band vertical designs.

The Superantennas MP-1 portable HF antenna is analyzed for its design and field performance, particularly its high-Q loading coil and 3/8-inch mounting. The review details the antenna's construction, including an 8-inch vertical section, a large-diameter loading coil tuned by a sleeve, and a 4-foot whip that disassembles into six rods for transport. Initial testing with the supplied 10-foot ribbon cable "ground plane" yielded poor SWR and RF hot conditions, indicating an inadequate ground system. Further experimentation with longer radials and resonant counterpoises for each band improved matching and eliminated RF hot issues, but introduced significant operational complexity. The author notes the difficulty in optimizing both counterpoise length and coil setting without an antenna analyzer, and the sensitivity of the MP-1 to counterpoise deployment. The review also discusses the recommendation to tune for maximum received signals rather than minimum SWR, often necessitating an external ATU due to the antenna's typical low impedance. The **MP-1**'s critical dependence on resonant counterpoises for effective operation, especially when elevated, is highlighted as a major drawback for portable use. The author ultimately sold the antenna, concluding that despite its sound technical design, its fussy nature and the need for extensive counterpoise management or an ATU detract from its portability and convenience compared to simpler, less expensive dipole solutions. The **Superantennas MP-1** is deemed a flawed portable antenna, requiring considerable effort to achieve its claimed performance.

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.

Learn about the POTA PERformer antenna, a portable, elevated, resonant whip designed by Greg Mihran KJ6ER. Discover how this unique antenna requires fewer radials to be efficient, making it ideal for portable operations. Explore the benefits of using two radials for a directional radiating pattern, compared to just one radial. Find out how computer modeling can help optimize the performance of the POTA PERformer antenna for your ham radio activities.