Precision Direction Finding Antenna Array (RA-NS)

RA-NS-RA-2A in Vertical Polarization

The RA-NS Precision Direction Finding Antenna series is designed for maximum accuracy and repeatability in direction finding with minimum field maintenance. The RA-NS series employs two beam antenna arrays, critically separated by a lightweight metal cross boom (model RA-CB). The received signals from both antennas are combined precisely out of phase, producing a pattern as shown in Figure 2. The deep forward looking null (-10 to -30 dBV) in the center is bound on either side (+ or - 15 to 30 degrees), by a point of maximum gain (peaks). When this system is combined with a compass rose assembly and Receiver capable of measuring signal strength (TR-5), a repeatable accuracy of ± 0.5 to 2.0 degrees can be attained when working with animals in conditions of relative inactivity and line of sight (LOS) conditions exist.

Null polarization plot
Null polarization plot

Key Features

  • 1 degree bearing accuracy is possible using the deep forward null in the pattern.
  • Accuracy is not dependent on the gain of the individual antennas selected.
  • Selecting lower gain antennas and using horizontal polarization minimizes the received signal bounce.
  • The use of the TAC-5 assures repeatable accuracy not possible with "old peak null" technology.
  • The array has been mounted on vehicles for portability as well as permanent installations at fixed sites.
  • The array comes standard with 2 17ft. cable lengths to accommodate mast heights up to 12 feet above ground level or vehicle level.
  • Alternative cable lengths are available by special order for an additional charge
Model Name / Description
of Antenna in Array
Antenna Gain Fixed Site Land Vehicles Boats and Ships
Vertical polarization only
(can be switched to horizontal polarization by using RA-NS-B bracket sold separately)
2 element "H" type
RA-NS-RA-3 element
RA-NS-RA-4A element
RA-NS-RA-4B element

Each RA-NS array includes:
2 ea. Antennas (see choices below)
1 ea. RA-CB cross boom
1 ea. RA-TC "Tee" clamp (connects boom to mast)
1 ea. TAC-5 Precision two port combiner
2 ea. RW-3-17 cables
(17 foot length accommodates mast heights up to 12 feet above ground level.)
1 ea. RW-2 cable (connects Combiner to Receiver)
1 ea. Set of drawings for mast base, compass rose assembly, antenna mounting and cable dress

Please Specify Choice of Antenna:
RA-3 - (*)

* Please specify choice of frequency band:

148.000 - 149.999 MHz 150.000 - 151.999 MHz 159.000 - 160.999 MHz
164.000 - 165.999 MHz 172.000 - 173.999 MHz  

Optional Equipment for RA-NS Arrays
RA-NS-B Bracket for switching a RA-NS-RA-2A from vertical to horizontal polarization
RW-3-25-BNC 25 ft cable accommodates mast heights up to 20 feet above ground

User Must Provide:
1 ea. 1.25 - 1.7 inch O.D. Mast, 17 feet long
1 ea. Mast Base with Thrust Bearing and Compass Rose Assembly

Technical Note about RA-NS arrays