Filtering Interference for Antenna Measurements
Authors: Steve Nichols, Roger Dygert
When making measurements on an outdoor range, susceptibility to electromagnetic interference is a common problem. In a dense spectral environment, television and radio broadcast signals, radars, and various communications systems emit signals that can be received by antenna measurement instrumentation. When these combine with the signal from the range transmit signal source at the receive antenna, measurement errors result.
To overcome interfering signals, one may consider increasing range transmit power sufficiently to limit the effects of interference on the measurement. However, the test range may then cause interference to other nearby systems. A better solution is to keep transmit power at a lower level and filter out the interferer.
The filtering techniques used in measurement instrumentation may or may not be adequate to prevent interference from affecting the measurement results. This paper illustrates that by choosing a sensitive receiver with high selectivity filtering, measurements can be made in the same band as the interferer.