Northern Prairie Wildlife Research Center
Larry M. Mechlin and Hollis G. Sapp, Missouri Department of Conservation, 1110 South College Avenue, Columbia, MO 65211 USA
Vehicle mounted antenna systems have been used for some time for wildlife telemetry, but often require major adjustments to the vehicle or awkward positions for the driver/operator to manipulate. This double yagi system mounts easily in the bed of a pickup and uses an electronic rotor that is remotely controlled from the front seat. This antenna system, in the erect or folded position still allows enough room in a short bed pickup for a four-wheel drive ATV. One person can easily move the antenna from the upright to the folded position or vice versa by removing or replacing one pin.
The antenna can be rotated from zero through 360° by moving the control knob to the desired position. If it is rotated 360° it will automatically stop so the coax does not wrap. The antenna can then be rotated in the opposition direction to any point back to 0° where it will again automatically stop. It takes the rotor 60 sec to make a 360° rotation. In the upright position the central tube of the vertically mounted yagi antennas is approximately 10 1/3 ft above ground level with approximately 3 ft of clearance between the lowest point of the antenna element and the truck roof. Greater antenna height is possible if a rack is installed across the back of the truck to support the antenna or if open bed space is not necessary. Greater antenna height may negate scanning while the vehicle is in motion. We conducted scans with our antenna system while traveling up to 50 mph. This system was used to track prairie-chickens from April through August in 1995 and 1996.
The rotor, DC to AC inverter, coax, flat steel, pipe, angle iron, and bearing cost approximately $225. Although other types of antennas would be possible, we used a null antenna system with four element yagi antennas that cost approximately $300.