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This resource details the fundamental aspects of deploying longwire antennas, emphasizing ease of construction and installation for shortwave listening (SWL) and broadcast reception. It covers wire gauge selection, suggesting 14 to 24 AWG for general use, with heavier gauges (14-20 AWG) for permanent outdoor installations. Guidance is provided for various deployment scenarios, including indoor setups where the wire can be run around a room, temporary outdoor installations from balconies using light 18-24 AWG wire, and permanent outdoor configurations requiring higher placement and slack for tree movement. Feeding methods are discussed, recommending coaxial cable (50-75 ohms) to mitigate man-made interference, with instructions for connecting only the center conductor to the longwire. Safety precautions are highlighted, particularly avoiding contact with power lines and conductive materials, and managing static electricity buildup by unplugging the antenna after use and bleeding off charges before connection. The article also advises against using outdoor longwires during thunderstorms or snowstorms due to static and lightning risks. Optimal height considerations are presented, advocating for the highest safe placement, ideally a couple of feet above underlying structures, to maintain free air space. The text mentions a personal setup with one end at a roof peak (20 feet) and the other at a 17-foot mast, illustrating practical deployment without strict height requirements beyond safety and clearance.

Theory and construction of a novel trapless center-loaded off-center-fed (cl-ocf) dipole or windom antenna for the 80, 40, 30, 20, 15 and 10m hf amateur radio bands

This PDF article from April 2001 QST details the construction of the "NJQRP Squirt," a reduced-size 80-meter inverted-V dipole antenna. The resource provides a general construction sketch, a photograph of the assembled antenna, and specific dimensions for PC-board insulators. The antenna consists of two wire legs, each approximately **34 feet long**, separated by 90 degrees, fed at the center. It is designed for operation on 80 meters (3.5-4.0 MHz) as a quarter-wavelength antenna, requiring a low-loss feedline and an external antenna tuner due to its non-resonant feedpoint impedance. Construction utilizes readily available materials, including 1/16-inch glass-epoxy PC board for end and center insulators, and #20 or #22 insulated hookup wire for the elements. The feedline specified is 300-ohm TV flat ribbon line, with a note on potential trimming for tuner compatibility. N2CX reports the antenna's center should be elevated to at least **20 feet**, with ends no lower than seven feet above ground, resulting in a ground footprint of approximately 50 feet wide. The design prioritizes NVIS propagation for local 80-meter contacts. DXZone Focus: PDF Article | 80m Inverted-V Dipole | Construction Notes | 34 ft element length

The page describes a Double-L antenna for 80 and 160 meters bands, designed by Don Toman, K2KQ, with a simple, effective, and ground system-free design. The antenna is a center-fed half-wave vertical with horizontal top and bottom sections, providing good performance without the need for an elaborate ground system.

Details the construction of a J-vertical antenna specifically for the 10-meter band, offering a practical alternative to a _Slim Jim_ design for 28 MHz. The resource outlines the use of aluminum tubing for the half-wave vertical section and coaxial cable for the quarter-wave matching section, providing specific calculations for element lengths based on frequency and coaxial cable velocity factor. It contrasts the performance of the J-vertical with center-fed dipoles and end-fed verticals, noting superior results in previous comparisons. The article further presents a more recent iteration of the J-vertical, constructed using a fiberglass pole and insulated wire, with updated dimensions for 28.8 MHz. It includes practical advice on weatherproofing connections and securing the antenna for durability against adverse conditions, referencing the survival of an original _J Vertical_ during 110 MPH winds in 1987. The SWR performance is reported as 1.1:1 at 28.6 MHz, maintaining below 1.5:1 across 28.3 to 29 MHz.

8 elements quad antenna for 2 meters band, centered on 145 Mhz

G5RV 40m Beam Antenna. Adding a 28 ft. piece of vertical wire to one end of a 102 ft. center-fed dipole turns it into a 40m beam with a very wide beamwidth

The **DF9CY Three-Element Antenna for 28 MHz** details the modification of a commercial PAN International CB antenna to optimize its performance for the 10-meter amateur radio band. This resource provides specific design parameters, including a design frequency of 28.300 MHz, a usable bandwidth of 600 kHz, and a return loss better than 20 dB centered at 28.270 MHz. It also specifies a gain exceeding 7.5 dBi and a front/back ratio greater than 20 dB. The feeding mechanism utilizes a **gamma match**, with setup instructions provided for its positioning. Modifications involved shortening each element's end by 40 mm, a straightforward process due to existing screw holes. The author also recommends replacing the original screws with V2A stainless steel hardware to prevent oxidation and upgrading the SO239 connector to an N-connector for improved reliability. EZNEC simulation files are available, showing azimuth and elevation diagrams with good front-to-back ratio and around 10 dB vertical attenuation. The antenna has been in service since October 1998, demonstrating good performance with 90 watts and even 750 watts, facilitating contacts with all continents from a modest 9-meter height.

A dual loop antenna, ZZ Wave Net HF Wire Antenna Project by VE6VIS. The antenna is basically a full wave 80 meter loop on top and a 40 meter loop on the bottom all supported from a 64 foot center support

The end-fed halfwave antenna is a resonant half wavelength long antenna like a dipole antenna except for it is fed at its end rather then in the center. This antenna is as old as radio and is probably best known as the Zepp Antenna

HF Horizontal Center-Fed Antenna

Operating on the HF bands, Kenwood's TS-990S and TS-890S transceivers represent their flagship offerings, providing advanced features for DXing and contesting. My personal experience with Kenwood gear, particularly the TS-590SG, confirms their reputation for solid receive performance and clean transmit audio, often noted in pileups. The TS-590SG, a popular choice for many hams, delivers reliable performance across the HF and 6-meter bands, making it a versatile station centerpiece. For VHF/UHF enthusiasts, the TH-D75A tribander offers 144, 220, and 430 MHz capabilities in a portable form factor. This handheld unit integrates D-STAR and APRS functionalities, appealing to operators who value digital modes and location-based services on the go. The inclusion of 220 MHz, a less common but valuable band, expands its utility for regional communications and specialized nets. Kenwood's enduring presence in the amateur radio market, dating back to 1955, underscores a commitment to quality and innovation. Their product range, from high-end base stations to feature-rich portables, continues to support a wide array of operating styles and technical requirements within the ham community.

Loop Recorder, a Windows-based software, offers continuous audio recording capabilities, specifically designed for capturing broadcasts from radio or internet radio sources. It features a **looping buffer** that prevents missing the beginning of desired audio segments, such as songs or specific transmissions. The application supports various audio formats including **MP3**, WMA, Ogg Vorbis, and WAV, allowing users to save recordings in their preferred codec. The software provides functionalities for scheduled recordings, enabling automated capture of content at predefined times. It caters to a range of users, from radio enthusiasts monitoring air traffic and scanner amateurs archiving communications, to professional environments requiring 24/7 broadcast storage or call center monitoring. The Pro version extends these capabilities for more demanding, continuous operational tasks. Compatibility spans multiple Windows operating systems, from Windows 9x up to Windows 10, ensuring broad usability across different system generations.

VE3SUN DX Monitor is a standalone Windows program which monitors the DX announcements available on the internet at DX Summit and presents the information in a sortable grid format and on a map centered on your location. Price USD 39.95

This antenna is not a true Windom, but rather an off center fed or OCF dipole works on 8 bands from 80 to 10 meters

A **mobile HF multiband antenna** project details the construction of a center and top-loaded design, optimized for 10 through 80 meters. This antenna incorporates a capacity hat positioned high on the whip for enhanced efficiency, differing from commercial bugcatcher designs. The coil construction prioritizes high Q and minimal loss through an air core, open spacing, and heavy gauge wire, contributing to its lightweight nature and suitability for portable operation with a proper counterpoise. Band switching is achieved by manually moving a jumper plug to various tap points on the coil, allowing for operation across multiple bands, with 17m being resonant when the coil is bypassed. The design, a result of nine months of experimentation by N1LO, includes detailed instructions for modifying a Hamstick antenna base, creating a jumper wire, and assembling the capacity hat using stainless steel wire and silver-bearing solder for robust connections. The loading coil utilizes nylon grommet strips around a PVC pipe for an air-core winding, ensuring high efficiency. Tap sockets are fashioned from silver-plated 5-way binding posts, providing low-resistance RF joints for band selection. Guidance on tap point determination emphasizes using an antenna analyzer like the MFJ 259B or 269 to achieve resonance, especially on 40m and 80m where feedpoint resistance can be low. The document also covers the installation of monofilament stays to maintain antenna uprightness at highway speeds, with specific attachment points for stability.

A dual-bander for 80M and 40m. An Extended Double Zepp (EDZ) is a 5/4 wavelength center-fed dipole. This article will introduce the Half-Extended Double Zepp (HEDZ) which has characteristics that a lot of amateur radio operators should find quite interesting

This drawing shows a simple 10 meter wire J-pole antenna designed for 28.4 MHz. It is a vertical, end-fed Zepp-style antenna made from common materials and intended for easy home construction. The main radiating element is a straight length of stranded copper wire, either 14 or 18 gauge, cut to about 16.5 feet. At the top, the wire is supported by an insulator, allowing the antenna to be hoisted vertically. The matching section is made from 450-ohm ladder line, approximately 7 feet 9.5 inches long, and shorted at the bottom. This matching stub transforms the impedance so the antenna can be fed with coaxial cable. The feed point is tapped about 6 inches above the bottom of the stub, with the shield and center conductor connected at the proper points. A choke balun is formed with five turns of RG-58 coax in a 4-inch diameter loop to help reduce unwanted RF on the feed line. The drawing notes that this antenna has about 0 dBd gain, similar to a dipole, but offers an omnidirectional pattern and low-angle radiation when installed high. Its main advantage is practical performance, simple construction, and effective coverage for 10 meter operation.

The 20-meter homebrew **Moxon antenna** project by 9Y4DD, Dave, details the construction of a 14 MHz directional antenna using readily available and repurposed materials. Initial SWR readings at 6 feet were 1.2 at 14.000 MHz, 1.4 at 14.350 MHz, and 1.1 at 14.175 MHz, with a subsequent increase of 0.1 on all frequencies when raised to 15 feet. The design adheres to specifications provided by L.B. Cebik (W4RNL). Key components include a discarded domestic water pump pressure tank as the center mounting bracket, 1/2-inch PVC conduit for spreaders, and 1/2-inch CPVC hot water pipe inserts to enhance rigidity. The total weight of the antenna is 12.625 pounds, with a material cost of U.S.$36.63. The spreaders are 165 inches from the center, utilizing 2.5mm sq. stranded copper wire for the elements. Dave's design incorporates hexagonal 'spider webs' of waxed twine to stabilize the flexible PVC spreaders, addressing initial issues with wind-induced movement. Separators cut from 3/16-inch Plexiglas maintain an 8.6-inch element spacing. The antenna demonstrated effective DX contacts with Europe from Trinidad, showing improved noise reduction compared to an inverted V.

Understanding antenna gain is crucial for optimizing an amateur radio station's performance, particularly when evaluating shortened or compromised antenna designs. This resource provides a simplified explanation of antenna gain, focusing on the concept of _capture area_ to demystify the often-complex mathematical formulas found in antenna theory texts. It contrasts full-size dipoles with shortened versions, illustrating how physical length directly impacts an antenna's ability to intercept or radiate RF energy. The article presents practical examples, such as a 20m dipole with **0 dB/d** gain and a shortened 20m antenna exhibiting **-6 dB** less gain due to reduced capture area. It further details the significant efficiency losses in various shortened ground plane antennas for 40m and 160m, showing how a 40m center-loaded ground plane might only radiate **7%** of input power. These comparisons highlight the trade-offs involved in using physically small antennas and underscore the importance of minimizing coil losses for effective operation.

NS6T's Azimuthal Map generator provides a web form for creating custom azimuthal projections centered on a user-specified QTH. Users can input their location using latitude/longitude coordinates, a Maidenhead grid square (e.g., IO91um), or a city name, with support for both US and international locations. The system processes these inputs to render a map displaying true bearings from the specified origin. Output customization includes options for distance, with a recommendation for 17500 kilometers and 8.5" x 11" paper size for integration with PSTRotator software. The generated PDF can be zoomed and clipped for use as a .jpg file in PSTRotator/Maps directories. The tool also offers an experimental color azimuthal map variant. City data for non-US locations is sourced from The World Gazetteer. The resource encourages user feedback and problem reports via comments on the associated blog, aiming for continuous improvement of the mapping utility.

Multiband Center-Loaded Off-Center-Fed Dipole (CL-OCFD) antenna that work on 80m 40m 30m 20m 15m 10m. The Center-Loaded Off-Center-Fed Dipole (CL-OCFD) antenna, developed by Serge Stroobandt, offers a versatile solution for amateur radio enthusiasts, covering multiple HF bands (80, 40, 30, 20, 15, and 10 meters) without the need for an antenna tuner. This innovative design utilizes a capacitor for resonance on the 80-meter band and a resistor to manage static charges. The CL-OCFD enhances bandwidth and simplifies operation, making it a significant advancement on OCF Dipole design.

The Double Bazooka Dipole is a very efficient single band antenna which is very quite, and does not require the use of a balun. This antenna consists of coax (RG58) or other 50 ohm type with the shield split at the center and the feedline attached to the open ends

The KD6WD Moxon Antenna Project details the construction of 50-ohm two-element wire beam antennas, specifically Moxon rectangles, for the 10, 15, 17, and 20-meter bands. It utilizes AC6LA's software for critical measurement calculations (A-E) based on center frequency and wire size. Construction involves 16-gauge silver-coated copper wire, 16-foot telescoping fiberglass crappie fishing poles as spreaders in an "X" configuration, and various hub designs including aluminum tubing or PVC joints. A 1:1 current balun is used at the feedpoint, with wire nuts for connections, often achieving a 1:1 SWR across the design band. The project highlights practical applications, such as running a kilowatt into the antennas for greyline DX contacts, consistently yielding excellent signal reports. Comparisons to quad loops show 4 to 5 S-unit improvements in both receive and transmit. The Moxon design, according to L.B. Cebik's analysis, offers superior forward gain and front-to-back ratio among wire beams. The author notes a "DX-Vane" effect where a freely suspended Moxon automatically points to the strongest DX signal. Attempts at dual-band operation (17/20 meters) with a single feed were unsuccessful, reinforcing the Moxon's monoband nature, with EZNEC plots provided for a 17-meter Moxon at 30 feet.

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 .

WB2VUO presents a practical examination of effective HF mobile antennas, focusing on the inherent efficiency challenges encountered on the lower bands, specifically 160, 80, and 40 Meters. The resource delves into the necessity of loading coils for mobile operation below 21 MHz, where full-sized antennas are impractical. It contrasts base-loaded and center-loaded designs, noting that base-loaded antennas are simpler for the average ham to construct but offer lower efficiency compared to center-loaded configurations. The author provides specific data for an 8-foot whip, detailing its electrical length and _radiation resistance_ across various HF bands, from **0.08 ohms** on 160 Meters to **16.1 ohms** on 12 Meters. This data highlights the extremely low radiation resistance on lower frequencies, which significantly impacts feedpoint impedance due to ground and feedline losses. The discussion includes practical considerations for feedpoint impedance, noting that a typical 8-foot whip on 10 Meters might present 30-45 ohms, allowing for acceptable SWR without an ATU. Construction sketches illustrate both base-loaded and center-loaded mobile antennas, with advice on material selection like galvanized steel for rugged bottom sections. The article also includes coil value charts from the _ARRL Mobile Manual_ for both base and center loading, emphasizing the importance of using large diameter wire to minimize losses and suggesting capacity hats to reduce coil inductance and improve performance on 160-40 Meters.

This page describes the loading coil (inductor) that W8WWV built for my center-loaded 160 meter band (1.83 MHz) vertical antenna.

The K5OE 2-meter vertical mobile antenna design, detailed in this resource, employs a 3/8-wavelength vertical section complemented by four shortened radials, forming an off-center-fed vertical dipole. This configuration creates a self-contained lower half, enhancing efficiency compared to traditional 1/4-wave monopoles relying on vehicle bodies for a ground plane. The article specifies construction using PVC components, 10-gauge insulated wire for elements, and provides precise dimensions in both inches and centimeters for the 25-3/16" (64 cm) vertical and 7-3/16" (20 cm) radials. Performance data indicates an honest 3 dBi of gain at 6 feet elevation (2 dBi free-space), with a pattern favoring the horizon, suitable for Low Earth Orbit (LEO) satellite communications. At 20 feet high, the same antenna exhibits almost 6 dBi of gain, with a nominal 50 Ohm feedpoint impedance at 146.850 MHz. Tuning instructions involve trimming element lengths, with the author achieving a 1.2:1 SWR by pruning the mast to 24-3/4" and radials to 7". The resource highlights the antenna's effectiveness for mobile LEO satellite uplinks, particularly at low elevations, and its suitability for fixed, mobile, or portable operations. The flexible wire elements allow for easy folding, making it a practical choice for backpacking. The original design by K5OE was previously hosted on aol.com.

The resource details the construction and performance of a dual-band 40/30 meter _Moxon_ antenna, evolving from an initial single-band 30-meter design that failed in a storm. It specifies materials such as four 10-meter fishing rods, galvanized iron TV antenna support pipes, 1mm diameter PVC-covered copper wire, and a piece of 75-ohm TV satellite cable for feedline. The document outlines the iterative design process, including initial resonance measurements of 9.9 MHz for 30 meters and subsequent recalculations to shift the center frequency by 300 kHz using _Moxon software_. Initial testing on a roof yielded SWR readings of 1.4:1 at 7.200 MHz and 1.5:1 at 10.280 MHz. After installation atop a 30-meter tower, the final SWR measurements were 1.1 at 7.130 MHz and 1.4 at 10.230 MHz, with a notable 30 dB front-to-back ratio on 40 meters. The 30-meter performance, while good, showed a front-to-back ratio of approximately 15 dB, suggesting a slightly high resonance. The antenna's placement on a 700-meter hill, with a significant ground drop in certain directions, is noted as a potential factor in its excellent DX performance, enabling daily contacts with the USA West Coast on 30 and 40 meters with 100 watts.

Two live MP3 audio streams provide real-time reception of meteor forward scatter signals, allowing listeners to hear radar echoes from meteoroid disintegration. The system operates on **67.25 MHz**, utilizing an Icom PCR-1000 receiver with a 6-element Yagi antenna pointed skyward. This setup detects reflections from ionized meteor trails created at altitudes of 80 to 130 km, using distant Channel 4 TV transmitters in the southeastern USA as signal sources. Scientists Rob Suggs, Bill Cooke, and Jeff Anderson of the Marshall Space Flight Center Engineering Directorate developed this experimental radar to monitor near-Earth meteoroid activity. A typical day yields about one meteor ping per minute, with significantly higher rates during meteor showers. The optimal listening period is generally around dawn, from 0800 to 1400 UT, due to Earth's orbital motion encountering more space dust on the dawn side. The system's **CW demodulator** processes the 67.250 MHz signal, presenting it at approximately 700 Hz with a 3 kHz bandwidth and AGC off, inverting the passband for Doppler shift analysis.

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

Inverted V antennas is a dipole with the center raised on a mast and the endpoints near ground. Calculate dimensions online.

A 3.42-meter (11-foot 2-inch) extended-length mobile antenna project is presented, detailing its evolution from an initial 1.65-meter design. W5JGV shares his journey in optimizing mobile HF performance, noting that increasing the top whip length significantly improved radiation efficiency by reducing coil losses and allowing for larger wire gauges. The article includes a comparative table illustrating substantial gain increases, with the 3.42-meter version showing up to 40.6% efficiency on 21.2 MHz compared to a half-wave dipole. Construction details are thoroughly documented, from the use of hard-wall copper pipe for mast sections to the fabrication of custom loading coils. The author explains the necessity of an insulating brace for self-supporting coils and details a unique rotational alignment mechanism for off-center mounted coils to prevent snagging on overhead obstructions. He also describes a "Z" winding technique for 75-meter and 160-meter coils, which minimizes copper losses and manages dielectric losses. The resource provides specific loading coil data, including wire gauge, number of turns, coil length, and inductance values for bands from 18 MHz down to 2 MHz. It emphasizes that these coils may require fine-tuning based on individual vehicle and whip configurations, suggesting an antenna tuner for optimal mobile station operation across multiple HF bands.

A Center-Fed Half-Wave Dipole is probably the simplest of antennas to construct and use. It is usually suspended between two supports, from it's end insulators, and has the feedline hanging from the center.

End-Fed Half-Wave Antennas (EFHWAs) are analyzed for their utility in portable QRP operations, emphasizing their simplicity, efficiency, and predictable radiation patterns compared to other portable antenna types. The discussion contrasts EFHWAs with vertical antennas, random length wires, and center-fed dipoles, highlighting the common pitfalls of each, such as ground system dependency for verticals and feedline issues for dipoles. The article details the electrical half-wavelength calculation using the formula L (Ft) = 468/F(MHz) and explains how EFHWAs can be resonant on harmonic frequencies, enabling multiband operation. Various deployment configurations are presented, including the inverted L, inverted Vee, sloping wire, and vertical setups, each with specific advantages for radiation angle and polarization. For instance, a vertical EFHWA offers a low angle of radiation suitable for DX contacts without requiring an extensive ground system. The resource also addresses the counterpoise requirements, suggesting a quarter-wavelength wire or connection to a metallic structure for decoupling. A schematic diagram for a simple parallel-tuned circuit tuner, based on the _Rainbow Bridge/Tuner_ design, is provided, detailing component values for 30 and 40 meters, including a 6 microhenry toroidal inductor and a 20-100 picofarad mica compression capacitor. The tuner's adjustment process for SWR matching is also outlined.

This PDF document, authored by KT4QW in October 2004, details the construction and modeling of a dual-band, horizontally polarized hanging rectangular loop antenna for **10 and 17 meters**. The design, adapted from *The ARRL Handbook*, utilizes _NEC4WIN95_ software for scaling and optimization, targeting a 50 ohm feedpoint impedance. The resource includes a bill of materials, step-by-step construction instructions, and a discussion of the antenna's radiation characteristics. It presents NEC-generated elevation and azimuth patterns, comparing the loop's performance to a half-wave horizontal dipole at the same height and frequency. The 17-meter element is centered at 18.140 MHz for low SWR across the phone band, while the 10-meter element is centered at 28.500 MHz. Construction involves 14-gauge stranded copper wire and Schedule 40 PVC spreaders, with the total wire length calculated by the formula: Length in feet = 1005/MHz. The feedpoint impedance can be adjusted by modifying the rectangular aspect ratio. The document specifies hoisting the antenna to at least a half-wave above ground for testing. It notes that a balun was tested and found to have no measurable effect on SWR or radiation characteristics. A 2-meter scale model is presented to illustrate the physical design, and a "rotator" string is incorporated for directional adjustment up to 90 degrees.

An antenna does not have to be resonant to work, as the primary reason for resonance is to eliminate the need for an impedance-matching device. A non-resonant wire dipole fed with open-wire line and an antenna tuner can function as an effective multiband antenna. Two wires are essential for powering an antenna, ideally with a balanced configuration like a dipole fed by parallel-wire line, though coaxial cable can be used with a 1:1 balun to mitigate RF feedback on the shield. Antenna gain is achieved by shaping and aiming RF energy, concentrating it in a particular direction, as seen in beam antennas or shaped radiation patterns of wire antennas. The function of an antenna tuner is to match the transceiver's 50 Ohm output to the antenna system's impedance, which can vary widely. Wire antennas do not always require center feeding; end-fed long wires or off-center-fed dipoles (Windom antennas) can be used, often requiring a counterpoise or radial system. Dipole antennas do not need to be perfectly horizontal; their legs can be bent, inclined, or even vertical, affecting feed point impedance. Vertical antennas shorter than a half wavelength necessitate a ground system, typically comprising radial wires, with more radials generally leading to greater efficiency. A 1:1 SWR indicates an impedance match but does not guarantee a good antenna, as an inefficient antenna with a poor ground system can still show a perfect SWR while wasting RF as heat. Always using the best feed line affordable is crucial for minimizing loss and maximizing RF signal delivery to and from the antenna.

Ham radio store and online shop

A slightly different 6M antenna project by N1GY, an Off center fed antenna for the 50 MHz.

Radio Center radiaficion, Gps, Garmin, Kenwood, Yaesu, Navilock, dealer in Spain

The Windom antenna was widely used in the 1930s and is named after the amateur that wrote a comprehensive article about it

W0OXB All-band Centerfed Zep Antenna 160m-6m

The N0KHQ Coax Square antenna, designed for 17 meters and built using RG-58 coaxial cable, presents an intriguing option for hams with limited space. L. B. Cebik, _W4RNL_, meticulously models and analyzes this array, clarifying its classification not as a modified Moxon, but as a distinct member of the "dual-coupled, 2-element, parasitic array" family. The design leverages the velocity factor of RG-58 (approximately 0.66-0.67) to achieve significantly shorter element lengths compared to full-size counterparts, resulting in a perimeter of 42 feet for the N0KHQ array versus 54 feet for a standard Moxon. _NEC_ modeling reveals the coax square's performance characteristics, including a forward gain of 5.6 dBi and a 23.7 dB front-to-back ratio on 18.118 MHz. While slightly less gain than a Moxon (6.0 dBi), its pattern exhibits Yagi-like nulls at 90 degrees, distinguishing it from the Moxon's wider beamwidth. The article also delves into the unique feedpoint considerations, explaining how the split braid and center conductor of the RG-58 driver effectively form a folded dipole, allowing for impedance transformation to achieve a good match for 50-Ohm cable. Despite its shortened elements, which inherently narrow the operating bandwidth, the coax square maintains satisfactory performance across the 17-meter band. The analysis emphasizes that while SWR curves are important, a holistic view of gain and pattern degradation across the band is crucial. This antenna is a viable solution for operators needing a compact, directional array, particularly for narrow bands like 17, 30, or 12 meters, where its high-Q performance is most effective.

Easy Quad calculator, enter center frequency to get a quad antenna size

An antenna system is more easily interfaced to a radio when the input reactance at the feedline terminals is low or close to series resonance

Design your owm HF shiortened dipole. Includes a diagram of a lumped-constant loaded dipole antenna that is intended to fit in available space, rather than requiring a full 1/2 wavelength, at a specified frequency

Presents the design and construction of the OK2FJ Bigatas, a portable, automatically tuned vertical antenna covering 80 through 10 meters. It details two distinct control systems: one utilizing BCD band data from Yaesu FT-857/897 transceivers, and another employing voltage level sensing for the Yaesu FT-817. The resource provides specific instructions for building the antenna's radiating element, loading coil with switchable taps, and the control circuitry, emphasizing the use of readily available components. The article outlines the physical construction of the antenna, including the use of duralumin tubes for the radiator and a PVC tube for the coil form. It specifies coil winding details, tap points, and the integration of radial wires for ground plane operation. The control electronics section provides schematics and component lists for both the BCD decoder (using a 74LS42 IC) and the voltage comparator (using an _LM3914_ bargraph driver), enabling rapid, automatic band switching without the minute-long tuning delays common in other systems. Crucially, the antenna achieves rapid band changes, with typical SWR values centered on common operating segments, such as **3.7 MHz** for 80m SSB. It also discusses modifications for CW operation on 80m and the trade-offs between antenna efficiency and full-range automatic tuning on higher HF bands, where manual adjustment of radiator length is suggested for optimal performance on 15m, 12m, and 10m. The resource includes construction photos and a discussion of cable requirements for reliable operation.

A simple antenna that can be erected very fast, only need one center support, and do not take up much storage room. Works from 40 to 10 meters band

The W1TAG LF Receiving Loop is a specialized antenna project for LF reception, designed to mitigate local noise and enhance weak signal pickup on the lower frequencies. This square loop, measuring 6 feet per side, utilizes 14 turns of #12 THHN wire wound on a PVC frame, offering a robust mechanical structure. The design incorporates a series-tuned circuit with a coupling transformer, allowing for tuning from over 400 kHz down to _45 kHz_ using a switched capacitor bank. Construction details include the use of 1.5-inch PVC pipe for the frame, with specific measurements for spreaders and drilled holes for wire threading. The two 7-turn sections of wire are connected at the center, providing an option for a center tap. The loop rotates on a 1-inch steel pipe, enabling directional nulling of noise sources. The tuning unit, housed in a box clamped to the PVC, employs a 1:2 step-up transformer wound on an _FT-82-77 core_ and uses relays to switch capacitance values from 50 pF to 6400 pF, providing precise frequency adjustment. The current setup connects to the shack via 100 feet of RG-58, feeding into a W1VD-designed preamp, with plans for a balanced, shielded twisted pair cable upgrade.

This is a popular antenna design as the performance is very good across the HF bands and requires little or no tuning. It is a dipole fed off center with a 4:1 current balun at the offset feedpoint. The antenna shown covers 80, 40, 20 and 10 meters with 15 meters and WARC bands