![background image](http://html.mh-extra.com/html/cobra/19-ultra-ii/19-ultra-ii_how-to-use-manual_2631053010.webp)
Installation (Cont.)
CB Antenna
Since the maximum allowable power output of the transmitter is limit-
ed by the FCC, the antenna is one important factor affecting transmis-
sion distance. Only a properly matched antenna system will allow max-
imum power transfer from the 50-ohm transmission line to the radiat-
ing element. In mobile installations (cars, trucks, boats, etc.), an anten-
na system that is non-directional should be used.
A vertically polarized, quarter-wavelength whip antenna provides the
most reliable operation and greatest range. The shorter, loaded-type
whip antennas are more attractive, compact and adequate for applica-
tions where the maximum possible distance is not required. Also, the
loaded whips do not present the problems of height imposed by a full
quarter-wavelength whip.
Mobile whip antennas utilize the metal body of the vehicle as a ground
plane. When mounted at a corner of the vehicle they are slightly direc-
tional, in the direction of the body of the vehicle. For all practical pur-
poses, however, the radiation pattern is nondirectional. The slight direc-
tional characteristic will be observed only at extreme distances. A stan-
dard antenna connector (type SO-239) is provided on the transceiver for
easy connection to a standard PL 259 cable termination. Cobra loaded-
type antenna models ATW-500, AT-55, ATW-1000 and ATW-400 are
highly recommended for most installations. Consult your Cobra dealer
for further details.
When installed in a boat
, the transceiver will not operate at maximum
efficiency without a ground plate, unless the vessel has a steel hull.
Before installing the transceiver in a boat, consult your dealer for infor-
mation regarding an adequate grounding system and prevention of
electrolysis between fittings in the hull and water.
3-Way Combinations Antennas are available which allow operation
of all three bands (AM-FM & CB), using a single antenna. However,
use of this type of antenna usually results in less than normal trans-
mit and receive range when compared to a standard-type “Single
Band” antenna designed for CB only.
6
19.ULTRA.MANUAL.qx 9/15/97 4:09 PM Page 10