MicroAir Avionics M760 - Antenna Mounting: Metal Airframes; Antenna Mounting: Non-Metal Airframes

Microair Avionics M760 Transceiver Installation & User Manual
M760Q Install & User Manual 01R12.doc Page 9 of 36 30
th
March 2010
3.3.1 METAL SKIN AIRFRAMES
For metal skin aircraft a ¼ wave whip is the easiest antenna to fit. Ensure that the antenna base and the
coax shield are firmly grounded to the skin of the airframe, on the inside of the aircraft. Ensure that any
anti-corrosion product, which may be used to seal the exterior surface, does not isolate the antenna base
from the airframe. For best performance the whip should be straight and vertical, when mounted on the
airframe.
Refer to the Microair Avionics website www.microair.com.au
for more detail on antennas suitable for
metal skin airframes.
3.3.2 NON-METAL SKIN AIRFRAMES
For non-metal airframes, a ¼ wave whip may still be used, but a ground plane must be installed, on the
inside face of the aircraft skin. The ground plane should ideally be circular, and as a minimum, have a
diameter of half the height of the whip. The ground plane should be fabricated from a lightweight metal,
eg thin aluminium sheet. For best performance the whip element should be as vertical as possible.
An alternative antenna for non-metal airframes is the Ground Plane independent dipole. This antenna is
physically similar to the ¼ wave whip, but has a small flexible stub antenna pointing downwards from
the antenna base. The stub section of the antenna takes the place of the ground plane, and simplifies
installation.
Avoid mounting locations which position the antenna parallel to nearby metallic airframe structures such
as tube framing, brackets, ribs, or frames. Metal objects which are close and parallel to the antenna will
adversely affect performance.
If the installation has two radios, the two antennas should be separated horizontally by at least the length
of the antenna. In the case of airband antennas this should be approx 1m (3ft). The further apart the
better.
Beware of fabric surfaces with silver dope finishes. The silver dope is a conductive surface, and will
screen antennas which are mounted internally.
Refer to the Microair Avionics website www.microair.com.au
for more detail on antennas suitable for
non-metal skin airframes.