frequency

80 Meter Pizza Pan Antenna - This is a resonant, half-wave, vertical antenna. It takes up little space in the back yard, was designed for operation on a single frequency 80 meter PSK net, and is reasonably inexpensive to construct by Chuck Hines, K6QKL

From Transmitter to Antenna - A collection of articles on the subject of impedance, impedance matching and high-frequency power transmission by G3YNH

Antenna Measurements - The electrical characteristics of an antenna that are of interest to obtain by direct measurement are the frequency at which the antenna is tuned, the gain and radiation pattern

Azimuth Radiation Patterns - Below VHF the change in the radiation characteristics of an antenna will change considerably from frequency to frequency, making antenna selection more complicated.

Earth Systems - In order to resonate at a particular frequency, an antenna needs to be at least one half wave length long. Antennas below a 1/2 wave are dependent on a ground system for resonance as well.

SARL Beacon Project on 40 Meters - The beacon project is a South Africa national system of beacons on the 40 meter band operating on a single frequency

VA3GRR - Radio Beacon - VA3GRR is a radio beacon, operating on the 10 meter amateur band. Its frequency is 28.205.5 MHz. It runs just under 5 watts of power into a vertical half-wave ringo style antenna

WA8YWO - 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

The Considerate Operator's Frequency Guide - A guide to where on the HF bands various modes and activities are generally found. All frequencies are in MHz

K9ZW Blog - With Varying Frequency - Amateur Radio Ponderings

Yuba Sutter Colusa Tri-County Online Public Safety Scanner - The Yuba-Sutter area's only known online public safety scanner, supporting agencies in Yuba, Sutter and Colusa Counties. Alpha-numeric support for frequency identification with the use of Winamp or iTunes media players.

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

FMI - FMI provides superior solutions in the design and manufacture of frequency control devices including Voltage Controlled Temperature Compensated Crystal Oscillators (VCTCXO), voltage controlled crystal oscillator (VCXO), Temperature Compensated Crystal Oscillators (TCXO), crystal clock oscillators, high temperature oscillators, surface mount and crystal oscillator products, phase locked sources and more.

Allocation of Radio Spectrum - This is the table of contents to a list showing how the radio frequency spectrum is allocated to different users in the United States.

New England Historical Radio Society - The New England Historical Radio Society Inc. is an organization dedicated to the preservation of commercial Morse Radiotelegraphy on medium and high frequency.

Radio Frequency Beacon Finder - This project is a radio frequency receiver that will help the user the trace the direction and distance of transmitter beacon(s) operating at 433MHz frequency by Cornell Univerity

Understanding propagation numbers - Quick reference table on understanding A K SFI indexes and how can be translated in usable frequency opportunities

The KA7OEI FT-817 pages - FT-817 Radio Modifications, Improving the FT-817 Noise Blanker, increasing output power, using rechargeable cells, epanding frequency range

Frequenzdatenbank.de - Frequency database for Germany. Emergency services, aircrafts, radio and paging system with over 2000 frequencies from all over Germany.

Tone Sound Frequency Sweep Generator - Generating of up to eight independent oscillatory processes per each channel with separate frequency, initial phase and amplitude controls.

SigJenny - SigJenny turns your PC into a flexible and powerful audio signal generator for free. It can create multiple waveforms, sweep, fire single or repeating tone bursts. You can save your sound as a wav file, display a frequency response, use SigJenny a bit like an oscilloscope, and do a very good impression of a police car!

Spectrum Analyzer Real-time FFT - Eight-channel Audio Spectrum Analyzer is a set of Real-Time Multi-Channel Gauges for investigation of data accepted from any ADC you will want or 16-, 24- and 32-bit ADC of sound card. WDM drivers support. FFT Spectrum Analysis, OscilloScope, Frequency counter, AC/DC voltmeter, Signal-to-Noise Ratio, Signal-to-Noise and Distortion, Spurious-Free Dynamic Range, Effective Number Of Bits, Total Harmonic Distortion, Inter-Modulation Distortion, Phase Shift. Special modes of dual-channel FFT spectral analysis: Separate channels spectra, Spectra of digital sum, difference, product of two signals, Spectrum of digital product of original signal and its fundamental, Spectrum of Real and Complex Transfer Function, Cross Spectrum. Standart weighing of spectra according IEC and CCIR. Oscilloscope modes (for dual-channel ADC) are: original signals, sum, difference, dependence of one channel on another, amplitude distribution of input signals.

Enable Low Cost RF Power Amplifiers - A new paradigm for low cost, reliable RF amplifier ‘pallets’ has been enabled by new circuit design, manufacturing and thermal management techniques

What's a diplexer? - It's a network that splits a signal to two or more loads, dependent on frequency. It is the simplest form of a multiplexer, which can split a signal into many different signal bands.

TVi Basics - making filters - TV Interference filters, making TVI filters, coaxial filters to eliminate TV interferences caused by radio frequency