Mobile tracking includes working from watercraft, or from cars or trucks outfitted with various antenna systems and cabled to tracking receivers and/or dataloggers. ATS specializes in designing and providing complete mobile tracking systems for biologists, conservationists and ecologists, and has for over twenty-five years. You can contact one of the specialists at ATS for complete details and assistance in equipping your project, whether tracking on land, or in watercraft.

The primary advantage of  mounting an antenna on a vehicle is that they may be much larger than those carried by hand. A larger antenna system with multiple elements (four, six or eight) can increase both the reception range and the directionality of the system. ATS provides complete radio tracking antenna systems for use both on land or on water, and utilizing either loop, yagi, dipole, or null-peak antenna systems. The type of system used depends on several factors, including the species being tracked, the topography over which the researcher is working, and the range, or distance, from the transmitters.

Depending on the project, use of a boat on water may be selected as a primary means of tracking, or as an adjunct to other methods. A number of antenna configurations may be used, from simple hand-held loop or H antennas, to large 10 or 15 foot high dipole towers, or rotating towers with a  yagi or null-peak antenna system (more below).  The reception range can easily be doubled by using an antenna mast mounted in the boat; in general, an increase of approximately twice the range for a doubling of antenna height can be realized.

Often loop antennas are used for tracking on water when large yagis are not practical. A loop antenna is small and portable and used when low frequency (30-50 MHZ) transmitters are being tracked in streams, rivers, and lakes. It is a type of directional antenna, but because the gain is much lower than a yagi antenna, the loop antennas range will be cut almost in half.

Anywhere an on or off-road capable vehicle may be driven, mobile tracking may be used. However, overhead foliage may limit antenna height if one is using a  mast-mounted design. One way to accomplish tracking work is to start working from inside the vehicle, and once you have closed in on the target animal, you may move to tracking on foot. Caution: be aware of the electrocution hazard presented by overhead power lines when tracking with tall antenna masts.

Like tracking over water, most any type of antenna may be used while tracking in a vehicle. A simple and portable dipole antenna set-up, magnetically mounted on the roof of the vehicle is one option. Here, the metal roof of the vehicle will serve to provide a ground plane for the dipole antenna. Since a dipole antenna will provide an omni-directional radiation pattern as opposed to a directional pattern, it is normally only used to determine presence or absence of animals. Once the tracker determines there are radio tagged animals present, he may continue tracking by changing over to a directional yagi type antenna.

For either type of tracking, another popular antenna configuration is the stacked yagi array. These systems are much larger and are mounted higher, usually on an antenna mast which can be rotated through 360 degrees . This will provide better range and directionality than a smaller hand-held antenna. ?Stacking? two antennas will approximately double the gain of the system.  By simply adding a special antenna switchbox, a null-peak antenna system is the result. This type of switchbox is available from ATS. In a null-peak system, the antenna arrays radiation pattern can be changed between a peak setting, which allows a wider antenna beam and a null setting, which effectively narrows the radiation pattern.

When switched to ?peak,? the antennas will allow the tracker to get a general idea of the direction of where the transmitter is located while at a greater  distance from the transmitter. Then, the ?null? setting will allow the tracker to directionally focus-in on the transmitter, but the detection range will be less than the peak setting. When using a null-peak system mounted on a vehicle, a compass rose can be used to determine which direction the antenna is pointing as it is rotated through the azimuth. Complete null-peak antenna systems including antenna elements and connecting rods, special low-loss cables and connectors, and compass roses, are all available from ATS.

Copyright © 2005 Advanced Telemetry Systems, Inc.