Tallysman AJ (Anti-Jamming) Antenna Option

Tallysman AJ (Anti-Jamming) Antenna Option

Jammers are becoming more prevalent even though, in many jurisdictions, they are illegal.  Jammers are indiscriminate.  They prevent the reception of wanted GNSS signals by emitting strong electronic “noise” in the same frequency band as the GNSS signals.  The result is the LNA (low noise amplifier) in the GNSS antenna saturates resulting in no signal being passed to the GNSS receiver.
Tallysman’s solution to this is to provide an AJ option to its single band TW3000 family of antennas.  This option modifies the radiation pattern of the GNSS antenna such that it is “deaf” to signals arriving from -10° to +15° from horizon while slightly increasing the gain of the antenna at zenith.  Since jamming signals typically originate at low elevations, using such an antenna mitigates a significant portion of jamming signals.
The AJ feature is available on the following antenna models:

GPS L1

GPS L1 + GLONASS G1

GPS L1 + GLONASS G1 + Galileo E1 + BeiDou B1

  • TW3010 / TW3012
  • TW3030 / TW3032
  • TW3040 / TW3042
  • TW3100 / TW3101
  • TW3142
  • TW3150 / TW3152
  • TW3320 / TW3322
  • TW3350/ TW3352
  • TW3370 / TW3372
  • TW3400 / TW3402
  • TW3440 / TW3442
  • TW3710 / TW3712
  • TW3740 / TW3742

Because the AJ feature reduces the antenna’s sensitivity to lower angle satellites, it is highly recommended to use a system which accesses more than one constellation, such as GPS + GLONASS to ensure continuity of GNSS fix.
This option will be available in mid-August 2018.  Please check the Ordering Guide to determine the Part Number modifier.

Radiation Pattern Comparison of an AJ antenna versus a Non-AJ antenna @1575MHz
(RH is black, LH is red)

Radiation Pattern Comparison AJ Antenna.png