Standard or AJ Antenna – Which Should I Use?
The standard antenna sees the entire view of sky, equally receiving signals from satellites at the horizon or the zenith and all points in between. However, there is increasing interference in the GNSS L1 band, whether unintentional from other transmitters like communications towers or intentional from illegal “privacy jammers”. The AJ antenna rejects signals for the lower elevation angles – where most of the interference comes from – and only receives signals from the higher elevation angles where the satellites are. Of course, this reduces the number of satellites the receiver will see, but for the timing application, only a few satellites are needed. Moreover, with multi-constellation receivers, there are an increasing number of satellites available. So you get all the performance in timing accuracy you would get with a standard antenna plus 20 dB or more of interference rejection.