Precision Direction Finding Antenna Array (RA-NS)

RA-NS-RA-2A in Vertical Polarization

The RA-NS Precision Direction Finding Antenna array is designed for maximum accuracy and repeatability in direction finding with minimum field maintenance. The RA-NS uses two antennas, 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 the plot below. 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 (e.g. the 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
Vertical polarization is standard
(can be switched to horizontal polarization by using RA-NS-B bracket sold separately)
RA-2A, 2 element "H" 4 dBd
RA-NS-RA-3 RA-3, 3-3 element Yagi 6 dBd
RA-NS-RA-4A RA-4A, 5-5 element Yagi 9 dBd
RA-NS-RA-4B RA-4B, 8-8 element Yagi 11.8 dBd

Each RA-NS array includes:

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

* When ordering, specify the frequency band for the antennas:

  • 148.0 - 152.0 MHz
  • 150.0 - 154.0 MHz
  • 158.0 - 162.0 MHz
  • 164.0 - 168.0 MHz
  • 168.0 - 172.0 MHz
  • 216.0 - 220.0 MHz (available only with the RA-2A antennas)

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 foot cable accommodates mast heights up to 20 feet above ground

User Must Provide:

11.25 - 1.7 inch O.D. Mast
1Mast support, bearing (e.g. RA-TB) to allow rotation, and Compass Rose with ~1-degree increments

Additional information important for users of the RA-NS system is included in the RA-NS Technical Note.