Intermodulation distortions caused by protection circuits against transient interfering voltages for receiving systems

Protective devices with nonlinear components (e.g. special suppressor diodes) that cause intermodulation distortion, particularly the second- and third-order harmonics, are studied. It is shown that increasing insertion loss due to increasing frequency and decreasing breakdown voltage limits the high-frequency cutoff. The discussion covers the arrangement of the protective devices for an H-Adcock antenna system, the transiant response of the unprotected and protected system, and the RF behaviour of overvoltage prediction devices. A protection circuit for maximum signal frequencies of 200 MHz is presented