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Antennas : 20M : 20 meter Vertical Antennas
  • 4m Tall Vertical Dipole for 20m - Constructed in May 2008, this innovative 4m tall electrically full-size halfwave vertical dipole, tunable to multiple bands, offers HF coverage despite its space-saving design. Inspired by cost-effective DIY alternatives, the antenna design departs from conventional center-fed approaches, utilizing asymmetrical dimensions. Despite resonance challenges, the antenna's performance remains viable, boasting broad bandwidth and adaptability, as demonstrated through SWR measurements and EZNEC predictions.
    [ Hits: 65 | Votes: 0 | Rating: 0 ]
Antennas : 40M : 40 meter Vertical Antennas
  • Vertical bazooka antenna for the 40m  new - A quarter wave vertical omni-directional antenna for 7 MHz. Formulas for dimensions in feet and meters are provided. Ideal radial angle is between 35° and 45°. Velocity factor (Vf) varies based on coax type.
    [ Hits: 129 | Votes: 7 | Rating: 6.85 ]
Antennas : End-Fed
  • TEFV Terminated End Fed Vee Antenna - The Terminated End Fed Vee Antenna (TEFV) is a travelling wave antenna with constant current distribution. Unlike traditional resonant antennas, TEFV operates without standing waves, using a terminating resistor for broadband efficiency. With a combination of vertical and horizontal polarization, it offers wide bandwidth from 1.8 MHz to 30 MHz, eliminating the need for a tuner. Key components include a 9:1 unun transformer and a 500-ohm terminating resistor. Grounding and counterpoise enhance performance, and it can handle power losses of up to 30%. TEFV provides an effective, versatile antenna solution for amateur radio and broadcast applications.
    [ Hits: 183 | Votes: 2 | Rating: 6.5 ]
  • Delta Loop vs End Fed Half Wave on 20m - Intrigued by a German OM positive experience with a 20m delta loop, the author replicated the design, noting its favorable 50-ohm impedance compared to their 40m version. Testing against a vertical EFHW, the delta loop excelled within EU but lagged at longer distances. Despite needing more testing, the user leaned towards the EFHW for its overall performance and practicality.
    [ Hits: 123 | Votes: 0 | Rating: 0 ]
  • G4WIF End Fed Half Wave Antenna - Opting for a visually appealing inverted L configuration, G4WIF anchors the End Fed Half Wave antenna to an old clothes line pole, seeking cost-effectiveness in their endeavor. Despite initial misconceptions about transformer components, a £7.95 investment in a T240-43 toroid and DIY mounting container resolves the issue. Reflecting on commercial alternatives, G4WIF's homemade solution proves both economical and sufficient for their amateur radio needs.
    [ Hits: 77 | Votes: 0 | Rating: 0 ]
Antennas : End-Fed : End Fed Half Wave Antenna
  • 1:49 unun for end fed half wave antennas - 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.
    [ Hits: 386 | Votes: 10 | Rating: 8.1 ]
  • End-Fed Half-Wave Antenna for 20m 40m 80m - How to Design and Build a Field Expedient End-Fed Half-Wave Antenna for 20m, 40m and 80m. This Shorty 80m EFHW comprises a 49:1 autotransformer (to match the very high impedance at the end of a half-wave wire), a half-wavelength wire for 40m (also a quarter-wavelength for 80m), a loading coil and a short tail wire. The coil and the short tail wire (about 6 feet) make up the other quarter wave on 80m.
    [ Hits: 139 | Votes: 1 | Rating: 4 ]
  • Comparing Mobile whip versus EF HW Vertical - PH0NO conducted field tests comparing a mobile antenna (DX-UHV) to an end-fed half-wave wire. Results on 20m showed the end-fed wire outperforming the mobile antenna, with a significant difference in signal strength. On 40m, the end-fed wire surpassed the mobile antenna in spots and reach. While the mobile antenna is more practical, the end-fed wire offers superior performance. Further testing is planned.
    [ Hits: 81 | Votes: 0 | Rating: 0 ]
Antennas : Feed Lines : Coax Stubs
  • The Quarter-wave stub - The Quarter-wave stub can be used for many purposes. If it is left with an open end it can be used as a notch filter to attenuate certain frequencies. A quarter wave length of a transmission line can also be used as an impedance transformer, to know more about the Quarter-wave impedance transformer
    [ Hits: 134 | Votes: 1 | Rating: 8 ]
Antennas : Horn
  • What is Horn Antenna - Horn Antenna - The energy of the beam when slowly transform into radiation, the losses are reduced and the focussing of the beam improves. A Horn antenna may be considered as a flared out wave guide, by which the directivity is improved and the diffraction is reduced. One of the first horn antennas was constructed in 1897 by Bengali-Indian radio researcher Jagadish Chandra Bose in his pioneering experiments with microwaves. The modern horn antenna was invented independently in 1938 by Wilmer Barrow and G. C. Southworth. This Horn model antenna is suitable employed in the UHF or SHF radio bands. Making this horn model antenna it will be easy for a beginner to make if it works in the 10GHz frequency, because small dimensions so it is not so difficult and also offers gain up to 25dBi.
    [ Hits: 74 | Votes: 0 | Rating: 0 ]
Antennas : Magnetic Loop
  • Automatic Magnetic Antenna Tuner - A Magnetic Loop Antenna is a resonant circuit employing a large inductor and adjustable capacitor. Efficiency depends on the inductor's size relative to wavelength. A Magnetic Loop Controller adjusts antenna tuning in real-time, syncing with Transceiver VFO movements. It communicates with various radios, enabling seamless tuning. Stepper motor resolution ensures accurate capacitor positioning, crucial for antenna performance. The Controller's firmware offers diverse functionality, enhancing user experience and antenna efficiency.
    [ Hits: 58 | Votes: 0 | Rating: 0 ]
Antennas : Portable
  • A Compact and Stealthy Field Portable Antenna - In the quest for an ideal field portable antenna, the author recounts experiments involving various wire configurations. While a previous candidate, a 41ft random wire, proved effective but lacked stealth, the search led to a surprising rediscovery of a design previously rejected—the Rybakov Antenna. With a focus on simplicity, rapid deployment, and multiband capability, the author explores the versatility of a 26ft Rybakov, avoiding the halfwave trap. The article delves into the antenna's performance and its potential as a discreet, resonant solution for field operations, addressing the challenges encountered during a POTA activation. Additionally, the Unun/Balun design used in conjunction with the Rybakov Antenna is discussed, providing insights into achieving a balanced system.
    [ Hits: 149 | Votes: 1 | Rating: 1 ]
Antennas : Shortwave
  • Active 3-30 MHz Hula-Loop Antenna for Shortwave - This active antenna for the shortwave band provides surprising performance, even indoors. As the name implies, the main loop is made from a Hula-Hoop with the metallic paint stripped off and a single turn of 14AWG copper wire inserted inside the hoop.
    [ Hits: 155 | Votes: 1 | Rating: 10 ]
Antennas : Theory : Antenna Gain Antennas : Theory : Impedance matching
  • Performance of 49:1 Ferrite Core Transformers - There are quite a few recipes for building a suitable transformer for an end fed half wave antenna (EFHW), but I was never sure I really understood the main principles. So, I wound a bunch of transformers, made measurements on them using my NanoVNA, learned how to get what I really wanted out of the VNA measurements, and in the process discovered how to build better transformers and be able to predict what they will do
    [ Hits: 151 | Votes: 4 | Rating: 7 ]
Radio Equipment : HF Transceivers : Yaesu FT-1000MP
  • FT 1000MP MK V and Keyclicks - YaesuFT1000MK V stands out with improved close-spaced SSB transmit performance, reversing a trend seen in other modern radios. Featuring a class-A mode, it offers clean HV finals when kept out of ALC. However, two significant flaws persist: the noise blanker causes receiver IM distortion, and the transmitter lacks wave-shaping on CW, resulting in pronounced keyclicks. Preliminary tests reveal strong keyclicks +1kHz and -1kHz, prompting a combined modification to address both issues.
    [ Hits: 27 | Votes: 0 | Rating: 0 ]
Software : Linux : Linux Distributions
  • Skywave Linux - Linux for shortwave and amateur radio monitoring. Supports popular SDR hardware and online streaming from KiwiSDR, WebSDR, and Spyserver sites. Articles about using Linux with your SDR devices.Skywave Linux, an innovative operating system, leverages cutting-edge technology for seamless access to radio signals globally. Ideal for regions with limited internet access, it effortlessly connects to a network of SDR servers, offering high-performance SDR operation without the need for extensive hardware. With pre-installed and configured SDR software, Skywave Linux simplifies signal discovery and operation for all users.
    [ Hits: 263 | Votes: 0 | Rating: 0 ]

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