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A very popular method of making a short dipoles resonate at a given frequency. This type of antenna is suitable for single band, narrow bandwidth use.

This dynamic DX Map aggregates various resources that will help radio amateurs to operate their stations in search of long distance contacts, DX. HamDXMap displays current MUF values and foF2 critical frequency values around the globe.

Online calculator for Input coil data, LC Resonant Frequency and L match

Naptech buys and sells quality test equipment from hp, tektronix, including spectrum analyzers & peripherals, oscilloscope, frequency counters timers, signal generators, multimeters & voltmeters, RF & power meters, microwave amplifiers

A squint at the world of LF This website was initially thrown together to provide ready availability to data being collected from the measurement of a transatlantic LF (Low Frequency) path.

The RFzero is a multi function signal platform developed for radio amateurs who wants to extend the Arduino skills in combination with RF. The RFzero board is largely compatible with the Arduino Zero and Arduino M0 boards, however, it has been carefully designed for flexible use in RF applications and with attention to the frequency spectrum and stability performance.

Homebew a frequency marker by 7N3WVM

Spectrum manufactures very high-performance, low-cost, GPS-disciplined time and frequency reference standards for industry, scientific, calibration, broadcast and amateur operators.

Radio Frequency Systems (Formerly Celwave, Cellwave, Cablewave),Wifi antennas, duplexers.

Main High Frequency Antennas from the 2009 LARC FARL Field Day, Ford Amateur Radio League. A document comparing antenna performances and flexibility among a G5RV an Carolina Windom and a Cushcraft R7 vertical antenna.

TS-850 is not much effective on AM since it does produce fairly clean audio, however while it does noticeably improve low-end frequency response

The Japanese-made Maldol MFB-300 HF vertical antenna offer extremely wide-band performance, with a specified frequency range of 1.0-60 MHz.

Article by W1TAG on operating modes used on low-banding. The 2200 meter band (135.7 - 137.8 kHz) is only 2.1 kHz wide, so voice work on SSB or AM is out. Find out the best modes on LF

A summary of common calling frequency for each digital mode on that band.

This antenna is an omnidirectional and multiband and it is well suited for DX enthusiasts with limited space. Each of the parallel circuits (trap) behaves like an isolator on its resonant frequency.

The National Frequency Coordinator\'s Council (NFCC) is an organization comprised of and representing amateur radio frequency coordinators of the United States.

The Doppler Effect allows the distance between a satellite transmitting from space and a radio receiver on the ground to be measured by observing how the frequency received from the satellite transmitter changes as the satellite approaches, passes overhead, and moves away.

Tabor electronics produces high-end function generator, universal counters/timers, synthesizers, pulse, function and arbitrary waveform. Frequency counters

RF Safety reource page with links and more documentation on radio frequency safety

A Scientific endeavor aimed at studying the properties and behavior of the ionosphere.

An exaustive document on frequency multipliers with a particular attention on ways to generate high frequency signals for microwave

With Varying Frequency - Amateur Radio Ponderings

High Frequency Expermental Beacon "WV". The Beacon operates on the frequency of 13.55567mhz. This Beacon is very low power. It operates under Part 15 of the FCC Rules and Regulations. It transmits with only 1.5 milliwatts of power

An Google Maps interactive layer showing Australian amateur radio repeaters. You can navigate and zoom as required and click on a repeater-site icon to display frequency, ctcss and other details and notes for that repeater.

This article will explain a few of the ways author use an external SDR and Linrad to enhance his K3 experience. Linrad is one of many available SDR receiver programs. The same could be done with any radio that lets you access its IF frequency output. Article from NCJ Nov Dec 2019

British Columbia Frequency Modulation Communications Association

A review of the HF ham radio bands, considere by far the most popular bands in the amateur service. HF bands offer local QSOs and world-wide propagation are all possible at almost anytime with careful selection of the right frequency for the time of day, time of year, and current state of the sunspot cycle.

Frequency calibration is a user adjustment on the rear panel. Learn how to calibrate the IC-746 Pro.

Ionospheric propagation maps MUF and critical frequency

Homemade RF limiter project, to protect the K3 receiver front-end for high radiofrequency based on the original KD9SV project.

Offer a Direct Digital VFO Kits (variable-frequency oscillator) using the Analog Devices AD9951 by WA1FFL

Description of the beacon hardware and DDS frequency source used for G4JNT personal beacon

High power, UHF, L-band, S-band, C-band, microwave frequency amplifier and oscillator devices, pulsed, CW, fixed-tuned, or tunable devices in the range of 600 MHz to 2000 MHz

This article describes the construction of a high performance transmitter and receiver for SSB (voice) communication covering the 14MHz (20 meters) high frequency amateur radio band with output range 15 to 20 watts and a top audio sound quality both on transmit and receive.

Examples of absorbtive low-pass filters in which the unwanted high-frequency energy is separated from the wanted output and then dissipated in matched resistors

Tecom industries product line encompasses a wide range of highly sensitive active and passive antennas for use in airborne and ground applications, providing complete coverage of the 20 MHz to 40 GHz frequency range.

Frequency Counter w/Selective Power Measurement, Microwave Sythesized Signal Generator

This project is a USB Audio, Serial and PTT interface for rigs that does not directly support digital modes provided by applications such as FLDIGI, WSJT-X and JS8CALL. Plug these interface devices into your Windows or Linux laptop or Raspbian Raspberry Pi and you can send and receive digital tones to/from your rig and automate the frequency and mode control and PTT control.

Quartslab has over 30 years of experience in supplying quartz crystals to the international communications market. Our product range includes the supply of quartz crystals in the frequency range 1.5 to 225 MHz in all popular holder types as well as crystal oscillators in DIL8 and DIL14 packages.

An interesting article on basics about Baluns, intoducing the skin effects on radio frequency currents and its effects on receiving and trasmitting article by VE7FO

The Amateur Radio network now known as the Caribbean Emergency and Weather Net was established in 1958 by Colonel Henry Frew, KV4BZ, for the purpose of having a general calling frequency for the Caribbean Islands and our North and South American friends.

The N0QBH QRSS project page, a couple of projects using available kits for improved frequency and timing stability. A configurable DDS VFO 100mW transmitter with LCD display and a modified Hans Sommers 40m 100mW transmitter

Article on radio frequency interferences, with a long list of common RFI cause, like Plasma TV, Solar panels inverters, fluorescent tube lamps.

This site is dedicated to experimental low frequency operation in the 160 to 190 kHz spectrum. LF beacon MO is no longer active. This page is retained only for reference information.

Cubical Quad Antenna On-line Calculator helps on defining the size of each element and spreader. Simply give the resonating frequency and it will calculate size of each element.

This website is in place to convey the importance of 14.300 MHz as a frequency of recognition

The San Bernardino Microwave Society, operating under the callsign _W6IFE_, serves as a significant technical hub for amateur radio operators specializing in frequencies above 1 GHz. This organization's influence extends across Southern California, providing a centralized resource for advanced RF experimentation and **regional frequency management** within the microwave spectrum. Its permanent value lies in its extensive archive of technical papers and project documentation, which are critical for operators engaged in high-frequency design and deployment. The society's infrastructure is primarily intellectual, focusing on the dissemination of specialized knowledge rather than a conventional repeater network. It offers a robust collection of technical papers from prominent members like K6PIP, K6BLG, and WA6EXV, covering topics such as Rubidium oscillator data, logging software, and filter design. This resource facilitates advanced amateur radio operations, including participation in microwave contests and the development of custom transverters for bands like 24 GHz. The site also details various member projects, such as the Owens Valley Radio Observatory Project, showcasing practical applications of **RF propagation analysis** and system integration. DXZone Focus: Microwave | Technical Papers | RF Propagation | Contest Results

Ham radio transmissions can interfere with television reception. This is called television interference, or ham radio TVI. Consumer adoption of cable television has significantly reduced ham radio TVI. But the introduction of IPTV, or television over phone systems, has brought ham radio TVI back, often with a vengeance. Here's why

small but dedicated group of radio operators who primarily operate on a simplex on a frequency of 147.435

Online HB9CV antenna calculator, accept as input the desired resonating frequency and provides dimensions for spacing and length of each element, including boom and radiator diameter.