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Electronic Interferences and Electromagnetic Compatibility

Figure 1: noise-modulated jamming, the jammer in 150° (VHF-Band radar)

Electronic Interferences and Electromagnetic Compatibility

The sources of extraneous electromagnetic radiations reduce receiver performance and are known as electromagnetic interference (EMI). Many complex electronic systems are installed on airports, into aircrafts or aboard ships. The ability of these systems to perform their individual functions without interference is known as electromagnetic compatibility (EMC). Sources of electromagnetic interference can be divided into the following broad categories:
 

Interferences
natural
man-made
incidental
functional
Interferences
natural
man-made
incidental
functional
Interferences
natural
man-made
incidental
functional

Receive systems are designed to include protective circuitry between the antenna and receiver to filter out off-frequency signals. This prevents or limits interference, desensitization, or burnout. Electromagnetic interference can be reduced or eliminated by using various suppression techniques. The amount of EMI that is produced by a radio transmitter can be controlled by limiting bandwidth, and using electronic filtering networks and metallic shielding. Depending upon the system, these protective devices may include filters, multicouplers, preselectors, and so forth. These devices can minimize interference caused by inadequate frequency separation or poor physical isolation between transmit and receive antennas.

Figure 1: noise-modulated jamming, the jammer in 150° (VHF-Band radar)