RF Module

An RF module is any component device that can receive, transmit, or process RF signals. In order for any RF system to work, there must be a transmitter (either wired or wireless), transmission medium (either air or cable), and a receiver. An RF transmitter module is the device that converts the message signal (voice, data) into a modulated RF carrier suitable for transmitting either over cable or over the air. This is the most complicated portion of an RF system. Once the message signal is converted into an RF carrier, either air or cable can carry the signal great distances. Air travel may be through a waveguide (discussed later), through the air, or through a cable. A receiver is the module for RF that decodes the RF signal and converts the message signal back to its original form. All Radio Frequency modules must be working properly for the whole RF system to work.

If the RF signal would dissipate before reaching its intended destination, it must be amplified to reach its destination, another form of Radio Frequency module is required, a repeater.

A repeater is a module for RF that is designed to receive, amplify, and re-transmit an RF signal. Typically, a repeater can regenerate the signal at the same frequency (if over cable) or a different frequency (if over airwaves). The reason the RF frequency is adjusted in free-space transmissions is to avoid two signals at the same frequency in the same proximity, causing interference.

What is RF? R F is a widely accepted acronym for Radio Frequency. RF refers to the communications capability of modulating a signal over common airwaves. Radio Frequencies are those that are located in the band above 20Khz (human ear can receive 20hz-20Khz), thus requiring some form of receiver (other than the human ear) to translate the signal into something usable. For a frequency to be considered RF, it is said to be at least beyond the frequency range of the human hear.

RF signals can be easily transmitted through the air using transmitters and receivers, as well as passed through wires. The most common method of transmitting RF over a wire is using Coaxial cable (coax). Coax cable uses solder-on or crimp-on connectors in a variety of sizes. Most high-power RF transmitters use cables for low frequency signals (voice and video frequencies), then once the signal is ready for modulation onto an RF carrier, the signal is typically carried to the transmitting antenna via waveguide . Waveguide is a metallic "pipe" that is tuned to the RF frequency so that there is virtually no loss introduced by the transmission medium. Typically, this waveguide is rectangular, and is designed for maximum throughput of the RF signal. Radio stations, Satellite transmitters, and TV station transmitters all use waveguide to carry the high-power RF signal from the RF transmitter modules to the antennas.

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