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Query: 17m 12m vertical
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A self-supporting vertical antenna design for stationary-mobile HF-VHF operation is presented, emphasizing ease of construction with common materials like a fiberglass fishing rod and PVC pipe. The design focuses on creating a set of no-tuner monoband radiators for bands such as **2m**, **6m**, 10m, and 12m, with an overall radiator support length of 3.3m. The construction process details the assembly of the antenna base using a magnetic mount, PL-259 connector, and PVC pipe sections, which then supports the telescopic fishing rod. Radiator extensions are cut to achieve quarter-wave resonance on specific bands, with detailed instructions for 6m (50-51 MHz), 10m (28.5 MHz), and 12m (24.9 MHz). For lower HF bands like 15m, 17m, and 20m, the design incorporates base-loading coils, with specific turn counts provided (e.g., 21 turns for 20m). The project also suggests using an _antenna analyzer_ for precise tuning of extensions and coils, moving beyond theoretical values to achieve optimal performance. The author, _IK1ZYW_, notes that for 80m and 160m, the antenna becomes less efficient as a vertical, suggesting alternative configurations like an inverted-V dipole or asymmetrical inverted-L.
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Constructing an HF End-Fed Half-Wave (EFHW) vertical antenna, the resource details the winding of a monoband matching unit, inspired by _AA5TB_, designed to provide a 50 Ohm impedance match without a ground plane or antenna tuner. It specifies the use of a _T200-2_ ferrite core for the transformer, outlining the 13-turn secondary and 2-turn primary winding process with enamelled copper wire. The document also describes the integration of a coax capacitor, whose length is critical for tuning and varies by band, with specific starting lengths provided for 20m, 17m, 15m, 12m, and 10m operation. The practical application section guides the builder through tuning the antenna using an antenna analyzer, emphasizing the iterative process of spacing secondary windings and trimming the coax capacitor to achieve resonance at the desired band frequency. It highlights the antenna's low angle of radiation, beneficial for DX, and claims up to 2 S-points improvement over a _G5RV_ or similar doublet when used as an omnidirectional vertical. A comprehensive shopping list, including specific part numbers from _Rapid Electronics_, is provided, along with advice on selecting fiberglass fishing poles for support and suitable antenna wire.
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Operating on the 12-meter and 17-meter WARC bands often benefits from directional antennas that offer gain and front-to-back ratio in a compact footprint. This resource details the construction of a dual-band wire beam, specifically a _Moxon Rectangle_ design, for these two bands. It outlines the use of fiberglass tubing for spreaders, _Flexweave_ wire for the elements, and an aluminum hub with die-cast flanges to create a robust structure. The design allows for a single 50-ohm feed point, simplifying station setup and minimizing feedline loss. The project provides specific dimensions and material choices, enabling a homebrewer to replicate the antenna. While inspired by L.B. Cebik's (W4RNL) theoretical work, this implementation focuses on practical construction techniques for a physical build. The resulting antenna offers directional characteristics suitable for DXing and contesting on 12m and 17m, providing an alternative to full-sized Yagis or compromise verticals, particularly for those with limited space.
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Demonstrates the iterative design and construction of a **tapped HF/VHF mobile vertical antenna** by K0EMT, detailing four generations of development. The antenna supports operation on 80m, 40m, 30m, 20m, 17m, 15m, 12m, 10m, 6m, and 2m bands. Initial designs, like Generation 1, featured a 3/8" x 24TPI bolt in a PVC end cap with a 1" aluminum tubing mast, resulting in a 9'9" overall length and resonance around 6.9 MHz with the full coil. Subsequent generations refined the mast and coil forms, transitioning from aluminum to copper tubing (Generation 3, found too weak) and eventually fiberglass for the coil form (Generation 4, in progress). Coil tapping points were adjusted to achieve resonance without an external tuner in Generation 2. The project outlines material costs, totaling approximately $25, and mentions a successful 28 MHz QSO with EA3XA using an ICOM IC-706 mk II at 100 Watts. For 80m operation, an external wire with the maximum coil setting is used, or a 56" extender below the coil for stationary use.