Bandwidth is a frequency range or range of values within which a device, system, or signal can be transmitted or processed without distortion or loss. This means that within the bandwidth, all frequencies or signal values are transmitted or processed with high accuracy and quality.
Within the bandwidth of a device, the amplitude-frequency characteristic (AFC) of the signal is sufficiently uniform to ensure transmission without significant distortion of its shape. Sometimes, instead of the term “bandwidth,” the term “effective transmission bandwidth (ETB)” is used. In the context of radio communications, the term “bandwidth” is applied to the parameters of the input stages of transceivers and aerial systems.
The width of the bandwidth is usually defined as the difference between the upper and lower cutoff frequencies of the AFC section. The bandwidth is expressed in frequency units (for example, in megahertz (MHz)).
Antenna bandwidth
As a rule, two classes of antennas are distinguished: narrowband and broadband. It is essential that within the operating frequency range, good impedance matching, specified gain, and directional pattern are maintained. The antenna bandwidth should not vary when tuning the transmitter or receiver frequency. Narrowband antennas include all simple resonant antennas, as well as directional ones, such as the “Yagi-Uda array” and the Ground Plane (GP) antenna. For example, a Yagi-Uda antenna designed for the amateur radio band of 144 MHz should have a bandwidth of at least 2 MHz (144–146 MHz) and optimal matching within this frequency range. In practice, bandwidth is often determined by the standing wave ratio (SWR) level.
Broadband or multiband antennas have a much wider frequency coverage, greatly exceeding that of resonant systems. These include log-periodic and helical antennas, as well as the Beverage antenna. However, there are exceptions; for example, a log-periodic antenna can be specially designed to operate within a narrow frequency range.
Bandwidth of digital systems
The term “bandwidth” describes the data transfer rate within a network. It refers to the amount of data that can be transmitted between two points over a specified period. Data entering the network is referred to as ingress traffic, while data leaving the network is referred to as egress traffic. Bandwidth is typically measured in bits per second (bps, not to be confused with baud) or sometimes in bytes per second.
Emission classification, Radio signal emission spectrum, Notch filter.