What are CPRA or Controlled Reception Pattern Antennas?

Controlled Reception Pattern Antennas or CPRA are adaptive beam steering antennas whose reception pattern can be adjusted to create nulls in the direction of interfering signals. They create a sort of spatial filter that eliminates signals from a particular direction while letting through signals from other directions. The CPRA antenna is connected to a processing unit that is responsible for controlling the reception pattern of the antenna. So, in the case of GPS Jamming, the CPRA antenna identifies the interference and controls the reception pattern by steering the beams towards the satellites and nulls to where the interference is coming from.

The CPRA antenna is connected to a processing unit that performs a phase-destructive sum of the incoming interference signals, this process being equivalent to making nulls towards interferers in the array radiation pattern. Simply put, CRPA antennas have been developed for rejecting radio frequency interference.

What makes CRPA especially attractive is the fact that it does not require any changes in the GPS receiver itself. It simply replaces the existing antenna.

Since Controlled Reception Pattern Antennas are based on beamforming, they require multiple elements. The number of antenna elements will help determine the resolution of the beams in the antenna pattern.

Controlled Reception Pattern Antennas are most often used to protect GPS/GNSS receivers from interference and jamming. Signals received from GNSS Satellites are usually very weak and are thus susceptible to deliberate or unintentional interference. It is very easy for an adversary to intentionally introduce RF interference into the GPS frequency bands, referred to as jamming, and deny the user position, navigation, and timing (PNT) data. Using CPRA antennas can help protect against this changing the antenna reception patterns to null out the jamming signals and direct the beams towards the satellites.

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