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The page provides detailed information on the G5RV antenna, its feeder arrangement, and efficient operation on HF bands from 3.5 to 28 MHz. It includes dimensions for installation in limited spaces, variations for different bands, and impedance matching details.

A switchable antenna for 80/160 meters by IK1ZOY. A new version of a 1/4L 80 m. dipole modified for use in 160 m. band. using it's own coaxial cable feeder to wrap a coil.

The G3TPW CobWebb antenna design provides a compact, horizontally polarized, omni-directional solution for 20m, 17m, 15m, 12m, and 10m bands. This antenna utilizes five full-size half-wave dipoles, each bent into a square configuration to achieve omni-directional radiation without the nulls typically found in straight dipoles. The design incorporates a single 50-ohm coaxial feedline with an integrated air-core choke balun, minimizing feeder radiation and reducing EMC issues. Construction details include using PVC-covered multi-stranded copper twin cable for elements, supported by a fiberglass cross. The document specifies tapping points for impedance matching to 50 ohms on all five bands, ensuring high radiation efficiency without lossy traps or loading coils. Physical dimensions are compact, with 2.6-meter (8.5 feet) sides and a total weight of 6 kg (14 lbs), making it suitable for mounting on a 20-foot aluminum scaffold pole. Detailed instructions for assembling the junction box, including terminal strip wiring and the coaxial choke balun, are provided with photographs and diagrams. The design emphasizes a confined electric field to reduce coupling to nearby conductors, which helps mitigate TVI and makes the antenna less sensitive to mounting height or ground conductivity.

How to make 450 ohm open feeder

The Windom is an Off-center wire multiband Antenna. The old version was fed just by a single-wire connected on 1/3 of antenna's overall length or with an open-line feeder (later versions). Here is another model with coaxial feeder, which is compatible with Solid States - 50 Ohm output transceivers .

Selecting an appropriate antenna system for shortwave broadcasting involves evaluating various types based on performance, cost, and operational parameters. This resource details the critical specifications for broadcast antennas, including average and peak power ratings, directivity, takeoff angle (TOA), horizontal beamwidth, and gain, emphasizing that a 100-kW transmitter requires an antenna rated for 150 kW average and 400 kW peak. It clarifies that low TOA signals travel thousands of kilometers, while high TOA is for local coverage, and nearly all modern shortwave broadcast antennas are horizontally polarized. The article explores specific antenna types, such as Log-Periodic Antennas (LPAs), which offer wide frequency ranges (e.g., 2-30 MHz) and directional patterns with 11 dBi gain, costing from $20K to over $100K for multi-curtain versions. Dipole arrays, also known as curtain antennas, are prevalent in international broadcasting, featuring steerable beams (±15° and ±30°) and mode-switching capabilities to alter TOA, with high/low pairs costing over $1 million. Fan dipoles are noted for omnidirectional patterns, smaller size, and lower cost for low-power applications, while rhombics, though simple, require resistive termination and incur several dB of I2R losses. Balun considerations are crucial, as most communications baluns are not rated for the higher average and peak powers of AM broadcast transmitters. Modern shortwave antennas utilize durable materials like Alumoweld wire rope for radiators and support elements, avoiding copper, fiberglass, or materials prone to stretching or deterioration. Feeder systems for high-power stations often require tapered-line baluns to convert 50-ohm unbalanced power to 300-ohm balanced for connection to the antenna.

The ZS6BKW multiband HF antenna, a design by ZS6BKW (G0GSF), functions effectively on multiple HF bands without requiring an Antenna Tuning Unit (ATU) for 40, 20, 17, 12, 10, and 6 meters. This antenna, approximately **27.51 meters** (90 feet) long with a 12.2-meter (40-foot) open-wire feeder, is a direct descendant of the _G5RV_ but offers superior multi-band resonance. It can be deployed as a horizontal dipole or an inverted-vee, with the latter requiring only a single support and maintaining an apex angle of at least 90 degrees to prevent signal cancellation. Performance data, recorded with an MFJ Antenna Analyser, indicates SWR values of 1:1 on 7.00 MHz (40m) and 14.06 MHz (20m), with SWR below 1.3:1 on 17m, 10m, and 6m. While primarily designed for these bands, the antenna can be adapted for 80m, 30m, and 15m with an ATU, preferably at the balanced feeder's base. The use of 450-ohm twin-lead for the feeder is recommended over 300-ohm for improved strength and reduced losses, especially in adverse weather conditions. This design, originally published in _RadCom_ in 1993 and featured in Pat Hawker’s "Antenna Topics," provides a compact and efficient solution for HF operation, particularly for those with limited space or resources.

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.

The original G5RV antenna system consists of a center-fed horizontal 102' wire plus a 34' length of open-wire 525-Ohm feeder. Louis Varney, the antenna system's developer, intended two other features. Learn more at Cebik website

The document details the optimization and construction of the _Maria Maluca_ antenna, a compact 6-band (20m-6m) directional beam. It presents a comparative analysis of shortwave antenna principles, highlighting the efficiency gains achieved by using an open feeder line and tuner as a resonant unit, contrasting this with the losses associated with traps or capacitive loads in multiband antennas. The resource specifically revisits an older South American 2-element design for 10, 15, and 20 meters, applying modern NEC-based software to develop a six-band version. Performance data is meticulously tabulated, showing impedance, free space gain, gain at 12m height, elevation angle, and front-to-back (F/B) ratio for each band from 20m through 6m. For instance, on 15m, the antenna achieves 5.1 dBd free space gain and 13.72 dB F/B ratio. The construction section provides practical guidance on element assembly using aluminum pipes and hose clamps, detailing the use of a heavy-duty glass fiber reinforced polyamide rod for electrical separation and bending strength. It also specifies the use of 450-ohm _Wireman_ line CQ 552 for the transmission line. The document includes diagrams for rod fixing, an air-wound balun, and a vertical elevation diagram for the 15m band, illustrating its DX qualification. It also discusses the antenna's suitability for portable and expedition operations, noting its compact transport dimensions (max 1.50m length, 12 lb weight) and quick assembly time (under 15 minutes). The author, Dipl.Ing. Helmut Oeller, DC6NY, is identified as a source for material kits.

The 10-meter EH Antenna document details the construction and performance of a specific EH antenna design for the 10-meter band. It describes the integration of an L+L balanced matching network, a key component for impedance transformation, and highlights the addition of a tuned coaxial trap. This trap, consisting of 8 turns of RG58 coax wound around PVC tube and resonated at 29 MHz with a 10 pF capacitor, effectively inhibits common-mode current on the feeder, stabilizing antenna tuning. The resource presents a circuit diagram in Figure 1 and assembly details in Figure 2, illustrating the use of PVC plumbing tube as host material for dipole cylinders made from recycled aluminum tubing. It also explains the fabrication of capacitor stators and slider sections from thin aluminum tubing. The author, Lloyd Butler VK5BR, discusses initial challenges with feeder interaction and how the tuned trap resolved these issues, leading to stable tuning. Limited backyard tests indicate that the antenna, with the trap fitted close to the input connector, might exhibit similar field strength for both low and high angle transmission, suggesting a potential skewing of the signal. The document references previous articles by VK5BR in "Amateur Radio" for further operational details of the matching network and trap functionality.

A Half wave antenna has a high impedance feed point. This can be matched using a 1/4 wave stub matching section and converts the 40m vertical into an L-shaped 20m J-Pole antenna. The 300 ohm feeder used for this purpose must be kept away from the ground.

Connecting centre fed antennas, dipoles, yagis, rhombics, loops to coaxial cable, unless care is taken, it is not difficult to end up with feeder radiation resulting in power loss and the radiation characteristics changes

Over 1,000 stations in approximately 60 countries were worked using this modified twin-lead folded dipole, demonstrating its effectiveness with just 4 watts on 20 meters. This design, adapted from an ARRL Handbook concept, eliminates the shorting strap found in traditional folded dipoles, simplifying construction while maintaining performance. It utilizes readily available 300-ohm TV antenna feeder ribbon, making it a cost-effective solution for radio amateurs. The antenna's robust construction allows it to handle up to 100 watts without issues, even without a **balun**. The inclusion of a variable trimmer capacitor at the stub provides flexibility for tuning across different frequencies within a band, a practical feature for operators using transceivers like the Icom 735. Formulas are provided to calculate the precise dimensions for any desired operating frequency, enabling customization for various **HF bands**.

Optimizing a G5RV or ZS6BKW multiband wire antenna for HF operation often involves addressing common SWR issues and understanding feedline characteristics. This resource chronicles the construction and performance evaluation of a G5RV, initially built for 80m, 40m, 15m, and 10m bands, by a newly licensed Foundation operator. The author details the selection of materials, including 3.5 mm stainless steel wire for the doublet arms and enameled copper wire for the open-wire feeder, and the initial decision to omit a balun based on common online information. The narrative highlights the initial disappointing performance, characterized by high receive noise and poor signal reports on 80 meters, despite the transceiver's internal ATU achieving a 1:1 match. This led to experimentation with a coax current balun and further research into G5RV myths, such as SWR claims and the necessity of a balun. The author then describes modifying the antenna to the ZS6BKW configuration, which involves specific changes to the doublet and feedline lengths, and integrating a 1:1 current balun wound on a ferrite toroid. The modifications resulted in improved reception and transmit performance across the bands.

A project of a 5 Antennas Relay Switch Box, all Switches & Relays have both contacts wired in parallel to improve reliability of operation, to prevent static build up, when an antenna is not in use the feeder coax is grounded.

The official web-site of the firm IK-Telecom, Finland, manufacturer of base station antenna-feeder systems

An overview of coax cable often called coaxial feeder or RF cable, used to feed antennas and deliver radio frequency power from one point to another

1:49 UNUN using two stacked FT240-43 cores for end fed halfwave antenna. To match the end fed half wave antenna to the coaxial feeder, it is necessary to have a matching network or transmission line transformer.

Maxdao: offer you 7/16, N coaxial connectors, jumper cables, feeder clamps and grouding kits, surge arresters & brackets, wall entries and microwave components used in base tower, power dividers, couplers

1500 watts PEP SSB is the power handling capability of the MFJ-989C HF Antenna Tuner, a popular choice among amateur radio operators. Users have shared a wide range of experiences, with some praising its durability and performance over decades of use, while others criticize its build quality and accuracy. The tuner features a built-in dummy load, SWR-wattmeter, and a balun for balanced line feeders, making it versatile for various antenna setups. However, discrepancies in RF power readings and SWR measurements have been noted, with some users finding the dual scale meter to be off by about 20% compared to a Bird wattmeter. Long-term users report that the MFJ-989C performs well with proper antenna setups, but caution against tuning at high power without initial adjustments at lower power levels. Some have experienced issues such as arcing when exceeding 400 watts, while others have had no problems even at higher power levels. The roller inductor and capacitors are functional, though some users have had to perform maintenance like tightening screws or cleaning components to ensure reliable operation. Despite mixed reviews, the MFJ-989C remains in production, suggesting continued demand. It's a tuner that requires careful handling and possibly some DIY fixes to achieve optimal performance.

Different types of feeders, SWR and matching

Article on antenna feed impedance and the importance of matching RF andtennas to feeders, including notes on Radiation resistance, loss resistance, and efficiency are also detailed.

Article descrive the different types including coax and open-wire feeder and waveguide.

The resource, "Conventional Use of Transmission Line," meticulously details the operational principles of transmission lines, emphasizing the Transverse Electromagnetic (TEM) mode of energy transfer. It clarifies that for a line to function purely as a transmission line, all currents must be confined internally, with external fields ideally zero. The discussion differentiates between balanced and unbalanced lines, asserting that while both require equal and opposite currents within the conductors, the key distinction lies in the voltage relationship of each conductor to the surrounding environment. It highlights that a good antenna pattern does not inherently confirm proper feeder balance, and that common-mode currents can lead to RF in the shack and increased noise levels, even without pattern distortion. The article further explains that a transmission line can become a radiating conductor if energy is applied in a non-TEM mode, leading to common-mode issues. It cites classic texts like Jordan and Balmain's "_Electromagnetic Waves and Radiating Systems_" and Kraus's "_Antennas_" to support its definitions of TEM mode operation. The content also explores non-transmission line applications of parallel or concentric conductors, such as _coaxial dipoles_ and _folded dipoles_, which intentionally operate in non-TEM modes for antenna functionality. The author, _W8JI_, stresses that simply measuring equal currents is insufficient to confirm a balanced feeder; phase and voltage balance to ground are equally critical.

Voldatech, a manufacturer based in China, produces a range of RF feeder cables and site components essential for amateur radio installations and telecommunication infrastructure. Their product line includes various types of coaxial cables, such as **50 Ohm** and 75 Ohm options, along with a comprehensive selection of connectors like N-type, UHF, and BNC. These components are critical for maintaining signal integrity and minimizing loss in antenna systems, whether for a home shack or a remote DXpedition setup. The company's focus on _RF Coax cables_ and connectors directly supports the needs of radio amateurs seeking reliable transmission lines for their transceivers and antennas. Amateurs often compare Voldatech's offerings to established brands, evaluating factors such as impedance matching, shielding effectiveness, and durability under various environmental conditions. The availability of diverse cable types allows operators to select optimal solutions for different frequency bands and power levels, from QRP to high-power amplifier setups. Their products are particularly relevant for those constructing new antenna arrays or upgrading existing feedline systems, aiming to achieve maximum power transfer and reduce standing wave ratio (SWR) for efficient signal propagation.

Unlock the secrets of RF signal optimization in a presentation covering Balun essentials, diverse types, SWR Analyzer checks, revealing results, Ferrite impedance measurements, and practical applications on feeders and house conductors.

The loops are made of 10 mm round aluminum tube. No bending pliers was used to gently bend 90 degrees to obtain a square with 53 cm inner sides. Each loop has an impedance of approximately 100 Ohm. To connect both radiators in phase, a quarter wave long feeder of 100 Ohm is required.

Online antenna calculator for a basic 3 elements yagi uda directional antenna. The described antenna design offers a front-to-back ratio of at least 20 dB, a gain exceeding 7.3 dBi, and a bandwidth (SWR < 2) of approximately 7% around the center frequency. It has an input impedance of 50 ohms when using a straight split dipole, which can be substituted with a folded dipole of the same length, increasing the impedance to 200 ohms. A matching balun is required for coaxial feeder connection, and the boom should be made of a dielectric material, like wood.

Helical antenna or helix antenna is the antenna in which the conducting wire is wound in helical shape and connected to the ground plate with a feeder line. It is the simplest antenna, which provides circularly polarized waves.

Demonstrates the ZS6BKW multiband HF antenna, a design by ZS6BKW (G0GSF) that improves upon the G5RV by offering direct resonance on multiple bands without an antenna tuner. The resource details the antenna's 90-foot length and 40-foot 450-ohm twin lead downlead, emphasizing its suitability for hams with limited space or budget. It covers both horizontal and inverted-V configurations, noting the inverted-V's single-support advantage and the importance of maintaining an apex angle of at least 90 degrees to prevent signal cancellation. The author, G3UKV, shares his preference for 450-ohm twin lead over 300-ohm due to its superior strength and lower losses, especially in wet conditions, drawing from his extensive field experience. The document presents recorded SWR and impedance (R) measurements taken with an MFJ Antenna Analyzer, confirming excellent performance on 40m, 20m, 17m, 12m, 10m, and 6m, often with SWRs below 1.3:1. It also discusses the antenna's tunability on 80m with an ATU and suggests a method for 160m operation. G3UKV recounts receiving "excellent reports" on 7 MHz and 14 MHz, validating the antenna's effectiveness. Practical advice includes keeping antenna ends clear of ground by at least a yard to avoid detuning and the recommendation of a 1:1 current balun where the 450-ohm feeder connects to 50-ohm coax.

This presentation on antennas is a practical guide for amateur radio operators. The key takeaway is that the best antenna for your station depends on your constraints and goals. There is no magic solution and buying a wire antenna is not recommended as it might be expensive and not as effective. The presentation covers different antenna types including dipoles, verticals, Yagis and loop antennas. Important factors to consider when choosing an antenna include SWR, feeder types, and whether you need a balun. The author emphasizes that ATUs don’t improve a poor antenna and advises against obsessing over SWR readings.

Fifty-one MHz operation, often called the "magic band," benefits significantly from a well-designed antenna, and this resource details the construction of a rigid 6-meter _Moxon antenna_ using common DIY store materials. The author, 4L/G8BAG, shares his experience with the 6m band, highlighting its potential for long-distance contacts, with single-hop sporadic E propagation enabling QSOs up to **2,500 km** and multi-hop contacts reaching **10,000 km**. The project emphasizes cost-effectiveness and durability, utilizing yellow gas pipe with an internal stainless steel lining for the antenna elements. The article provides specific dimensions for the Moxon rectangle, derived from the 12mm internal diameter of the gas pipe's steel core, rather than the outer plastic. It also details the use of white PVC water pipe for insulators and mounting, ensuring a tight fit with the yellow gas pipe. Initial testing with an MFJ antenna analyzer showed an excellent 1:1 SWR across the 50-52 MHz range, even when using 75 Ohm satellite cable as a feeder. The construction process is straightforward, involving cutting and bending the gas pipe, fitting insulators, and connecting the feedline. The author's successful on-air results, including a 1000 km contact with a temporary vertical, underscore the effectiveness of the 6m band and the Moxon design. The resource concludes with a note on exploring heavier gauge gas pipe for future 10m antenna projects.

VE2AZX's 2013 Radio Talk presentation details the technical aspects of baluns, including reasons for their use, various types, and methods for performance verification using an SWR analyzer. The document specifically examines 1:1 voltage baluns and 4:1 voltage baluns, outlining their winding configurations and typical impedance transformations. It presents empirical SWR measurements for W2AU 1:1 baluns and Unadilla 4:1 baluns, tested with both 50-ohm and 200-ohm resistive loads across the HF spectrum. The presentation further explores the measurement of ferrite impedance and their application in mitigating common-mode currents on feeders and household conductors. Key concepts addressed include balanced-to-unbalanced transformation, ensuring feeder independence from the antenna, and reducing unwanted feeder radiation. The content emphasizes practical testing procedures to ensure optimal antenna system performance and minimize RF interference. Discussions also cover open-circuit tests with SWR analyzers and VNAs to assess winding inductance, distributed capacitance, and insulation quality. The presentation differentiates between voltage and current baluns, explaining how current baluns, particularly those utilizing ferrite cores, reduce outer shield currents without affecting internal coaxial cable currents, thereby preserving the antenna's intended radiation pattern.