With the rapid advancement of modern competition in information technology, many RF radios are being used simultaneously within a single frequency band (a typical example is the VHF band). The mutual interference of RF signals between these radios can only be mitigated using high-performance narrowband frequency-hopping filters.

When used in receiver systems, the out-of-band rejection capability of the narrowband frequency-hopping filter largely determines the sensitivity of the entire receiver communication system. In transmitter systems, these filters help suppress radiated interference from intermodulation signals in the transmitter.

A typical frequency-hopping filter consists of five components:

As electromagnetic signals become increasingly dense and complex, users demand higher anti-interference capabilities for communication countermeasure equipment. Frequency-hopping radios, as a new generation of communication countermeasure equipment, possess strong anti-interference and anti-interception capabilities, showcasing significant advantages in modern electronic warfare.

Digital modulation frequency-hopping filters are a critical component specifically designed for this new generation of communication countermeasure equipment. These filters are placed at the front end of the receiver or the transmitter power amplifier (high-power frequency-hopping filters are placed after the power amplifier).

Their purpose is to achieve channel separation, prevent blocking, and suppress unwanted electromagnetic signals. As a result, they play a decisive role in determining critical equipment performance indicators, such as sensitivity, noise figure, and intermediate frequency (IF) and image frequency rejection.