The Desense Effect

A strong, nearby transmission from some other radio will make it harder for your radio to hear your desired signal. Your receiver can be overwhelmed by the interfering signal. This “desense” effect can be mitigated by:

• Moving your antenna as far away as possible from the interfering radio’s antenna. In a multi-antenna location, separate the antennas vertically and horizontally.
• Filtering the other radio’s transmitter to reduce spurious signals in the same frequency range where you’re trying to receive.
• Filtering your radio’s receiver to reduce spurious signals that are outside the frequency range that you’re trying to receive, but still strong enough to desense your receiver.

Desense works both ways. Moving your antenna further away and filtering your transmitter can help to prevent your station from interfering with others. FCC regulations require stations to avoid interference whenever possible.

The Antenna Fundamentals class goes into more detail on antenna placement and other interference issues.