XM Satellite Radio XMD076A - Manual (Page 13)

Installation Manual
XMD076A
XMD076A-3 Information is subject to the 9
Rev C , 06/22/06 restrictions on the title page
H E A D S U P T E C H N O L O G I E S
2.4 XM Satellite Antenna Installation Considerations
The XMD076A is designed for use with various XM Radio type-certified antennas
covering the S-Band from 2.332 GHz to 2.345 GHz. Due to the low signal levels
inherent with satellite communications, the following guidelines and recommended
practices should be adhered to for the design of the antenna installation:
•
Install IAW AC 43.13-2A Chapter 3, AC 43.13-1B Chapter 11, antenna
manufacturer instructions, and in a manner acceptable to the administrator.
•
Mount the antenna on the top of the aircraft to an external surface such as the
fuselage, away from vertical obstructions as to not “shadow” the antenna from
line-of-sight reception of the satellites. (Mount antenna as high on the fuselage
as practical). Relocation of other less location-sensitive transmitters may be
necessary to achieve optimal XM reception performance.
•
The mounting of the antenna must provide an electrical bond of 0.003 Ohms or
less the airframe ground.
2.4.1 Antenna Coaxial Cable Installation
The correct cable loss of the antenna feed cable is critical to the performance of the
system operation. The design configuration of the receiver’s input is preset to expect a
total gain range of 22dB (+/- 2dB).
Typical XM Radio type-certified aircraft antennas are configured with a total gain of 30-
34dB where 10dB of total cable loss provides the correct gain to the receiver. Always
refer to the antenna specifications to insure the correct gain. If desired, additional loss of
0.3dB for each SMA connector can be added but is not crucial to system performance.
Table 1 below provides reference information for lengths for various 50-ohm cable types
that are commonly used with SMA connectors to produce the acceptable loss when
used with antennas with 30-34dB of gain.