Honeywell BENDIX KING KMH 880 System Installation Manual page 50

B B
B B
Obstructions and ground plane discontinuities, such as door hatches, cowl-
ings and unriveted airframe skin overlaps must be 18 inches from the near-
est edge of the TAS Antenna. Other antennas, particularly high profile and L-
band transponder antennas, cannot be located in front of or within 30 inches
(edge to edge) of the top mounted TAS directional antenna. This will ensure
a minimum of 20 dB of isolation at 1090 MHz, while minimizing far-field path
distortion in the forward quadrants.
B. Mount the antenna on the aircraft skin which is horizontal during enroute
flight. Antenna baseplate must be level within + or - 5° in longitudinal and lat-
eral axes when the aircraft is in level flight. See Figure 2-4.
C. The antenna must be mounted on a nearly flat surface such that the antenna
contacts the bare metal skin all around the perimeter without gaps when nor-
mal mounting screw torque is applied.
Aircraft with fixed landing gear must be equipped with a bottom mono-
pole antenna. Furthermore, the landing gear discrete must be strapped
to the retracted position. The bearing from a bottom directional is inval-
idated when landing gear is extended, so it would always be invalidated
on a fixed-gear aircraft. (Therefore, there would be no use for a directional
antenna.)
Page 2-14
NOTE
10609I00.ZIPCDL
KMH 880/KTA 870
Rev 0, October/2000