Search results

Another approach to hidden HF antennas

F6EZX presents a detailed account of constructing a compact, multi-band _Levy antenna_ for portable holiday operations, specifically addressing issues with local QRM from a previous _Deltaloop_ setup. The article outlines the design criteria, including multi-band operation on 40m, 30m, 17m, 15m, 12m, and 10m, a symmetrical configuration to reduce interference, and a low take-off angle for DX. Construction involves 2x 10.3m radiating elements and a 15.3m open-wire feeder (ladder line) with 7cm spacing, made from 1.5mm2 copper wire and foam pipe insulation spacers. Theoretical calculations, referencing F9HJ's "_Les antennes Levy_" book, guide the determination of element lengths and feeder impedance characteristics, aiming for a good match across bands with a commercial antenna tuner. Initial field tests with the _VCI Vectronics VC300DLP_ tuner showed a 1:1 SWR from 80m to 10m, with some difficulty on 17m. The antenna, mounted as a 45-degree slopper with the high point at 12m, successfully facilitated DX contacts to South America, particularly Chile and Argentina, suggesting a lower take-off angle compared to the previous Deltaloop which favored Brazil. The Levy antenna significantly reduced TVI/RFI, attributed to its improved symmetry and greater distance from the QRA. While signal reports on 15m and 20m were 1-2 S-points lower than the Deltaloop, its performance on 40m and 30m was comparable, fulfilling the design goals for a portable, low-cost, multi-band solution.

A quarter-wave vertical antenna design for HF operation offers a practical solution for radio amateurs seeking a compact and efficient multi-band radiator. This project details the construction of a 5-band HF vertical, drawing inspiration from established commercial products such as the _DX COMMANDER_ and the MV6. The design emphasizes ease of assembly and disassembly, making it suitable for portable operations or installations with limited space. The article provides insights into various construction methods and offers practical tips for building a robust yet lightweight antenna. It highlights the benefits of a vertical configuration for DX contacts, particularly on the lower HF bands, and discusses real-world performance observations. The antenna is designed to cover multiple HF bands, providing versatility for various operating scenarios. Operators can achieve significant DX results with this type of antenna, often comparable to more complex arrays, especially when deployed with an effective ground system. The project aims to empower hams to build a capable antenna without significant financial outlay.

Operating a ZS6BKW antenna often involves understanding its lineage from the _G5RV_ design, with specific modifications by ZS6BKW to optimize performance on several bands. Through computational analysis and field measurements, the antenna's dimensions were refined to allow operation on 10, 12, 17, 20, and 40 meters without an antenna tuner. For 80, 30, and 15 meters, a tuner is necessary, though efficiency on 30 and 15 meters is noted as not particularly high. The physical configuration consists of two 13.755-meter radiating elements fed by a 12.20-meter section of 450-ohm ladder line. Tuning the antenna on the 20-meter band is critical, and any deviation in the ladder line's characteristic impedance necessitates recalculating the element lengths. The design is also referenced in the 12th edition of _Rothammel's Antennenbuch_, page 219. Proper common mode current suppression is crucial at the transition from ladder line to coaxial cable. This can be achieved with a common mode choke, such as several turns of coax wound into a coil or over a ferrite toroid like an Amidon T130. While a 1:1 balun is an option, it may introduce issues.

Antenne Cadre Project by F5NGZ, description by F5TZA in french

The antenna is a vertical dipole, around which four parasitic elements are forming a circle.

An antenna originally planned in the sixties, a two element beam antenna tunable on several band, in french

Presents the Aceco product line, focusing on their range of frequency counters, RF testers, and specialized bug finders. It details the capabilities of the _FC-1000_ and _FC-2000_ series as user-friendly, affordable frequency counters operating up to 3 GHz. The resource also highlights the _FC-3002_ as a portable RF finder capable of automatically tuning _ICOM CI-V_ or AOR scanners to detected signals, emphasizing its utility in secure monitoring. Furthermore, it describes the _FC-5000_ series as a wideband FM receiver that rapidly locks onto and demodulates FM signals, outputting audio through a built-in speaker, making it suitable for counter-surveillance and radio communication testing. The page provides technical specifications and operational distinctions for each product series. The content is structured to differentiate between the core functions of frequency measurement, signal tracing, and FM signal demodulation across the various models. It clarifies that these devices are not traditional scanners but offer faster signal acquisition for specific applications. The information is presented in both English and German, with a note indicating ongoing translation efforts for the German sections. The resource serves as a product catalog and technical overview for Aceco devices, distributed by WiMo Antennen und Elektronik GmbH, providing essential details for potential buyers interested in RF measurement and surveillance tools.

A bazooka antenna design in German with dimensions for 20m and 40m band with RG174 coax cable stronger than the common RG58

Only 2x 10ft wide, performance similar to full-size dipole, covers whole band with SWR better than 1:1.2.

Building EH Antennas at Gemran radio club station house, by Matthias DH4FAW

A page describing how to home made a custom 9:1 balun for a common portable wire antenna. The author suggest to use 4C65 or FT140-61 toroids instead of the common Amidon T200-2

A multiband J-Pole antenna project that cover 144,220 and 430 MHz. The articles includes several pictures of this multi-band antenna, including handmade schematics and diagrams, project is mainly in Italian

This antenna was conceived mainly for high-speed digital transmission via satellite. The antenna is made of two full waves loops , mounted at right angles to each other. Then coupled together, 90 degrees out of phase over a horizontal circular reflector. With this configuration the antenna is omni directional and circularly polarized.

Constructing an End-Fed Half-Wave (EFHW) antenna offers a practical solution for HF operators seeking a multiband wire antenna without the need for extensive radial systems. This design typically employs a high-impedance transformer at the feed point, matching the antenna's inherent high impedance to a 50-ohm coaxial feedline. The article specifically details a 2012 approach, focusing on a transformer with a 49:1 turns ratio, which is a common configuration for EFHW antennas. The resource outlines the construction of a wire element cut for a half-wavelength on the lowest desired band, with specific coil arrangements enabling operation on harmonically related bands such as 40m, 20m, and 10m. It discusses the physical dimensions and winding details for the matching transformer, often utilizing a ferrite toroid core to achieve the necessary impedance transformation. The content provides insights into the operational principles and practical considerations for deploying such an antenna, including methods for tuning and optimizing performance across multiple amateur radio bands. While acknowledging that the presented information from 2012 may be superseded by newer insights, it serves as a foundational reference for understanding EFHW antenna theory and construction.

A coaxial cable trap is a fundamental component in multiband antenna design, enabling a single radiator to resonate efficiently on multiple frequencies by electrically shortening or lengthening the antenna element. This project focuses on constructing such a trap for a vertical antenna operating on the 10 MHz (30m) and 14 MHz (20m) amateur bands, providing practical insights into its fabrication and integration. The article outlines the specific dimensions and winding techniques for the coaxial trap, emphasizing the use of readily available materials. It details the physical construction of the vertical element, including the mast and radiating sections, to achieve optimal performance across both target bands. The author shares personal experiences with similar trap designs, noting their effectiveness in previous horizontal dipole configurations. Key construction steps are illustrated with _original photos_, showing the assembly of the trap and its incorporation into the overall antenna structure. The design aims for a compact footprint, making it suitable for limited space installations while still delivering effective DX capabilities on the **30-meter** and **20-meter** bands.

The Slim Jim VHF antenna, originally designed by G2BCX, is a folded half-wave dipole fed by a quarter-wave matching section. This version, built from a recycled professional aluminum dipole, demonstrates that various materials—such as copper, brass, or twin-lead—can be used. The article details the antenna’s construction, required materials, and tuning process, emphasizing mechanical stability and ease of assembly. With proper adjustment of the feed point, it provides excellent SWR across the band. Its durability and simplicity make it a practical and efficient VHF antenna solution.