Precision Direction Finding Antenna Array (RA-NS)
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.
- 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
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:
|2||Antennas (see choices in Model table above)|
|1||RA-CB cross boom|
|1||RA-TC "Tee" clamp (connects boom to mast)|
|1||TAC-5 Precision two port combiner|
(17 foot length accommodates mast heights up to 12 feet above ground level.)
|1||RW-2 cable (connects Combiner to Receiver)|
|1||Set 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:
|1||1.25 - 1.7 inch O.D. Mast|
|1||Mast 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.