Garmin GTX 3x5 Series Installation Manual

Also see for GTX 3X5 Series: Installation manual Pilot's guide Installation manual Pilot's guide

Contents

Garmin GTX 3x5 Series Installation Manual Manual pdf 33 page image

190-01499-02 GTX 3x5 TSO Installation ManualRev. 1 Page 3-73.8 Antenna ConsiderationsMounting location considerations for the antenna(s) is provided in this section. The recommended antennaplacements are illustrated in figure 3-1.3.8.1 Transponder AntennaNOTEFor installations on composite aircraft, ground planes must be considered. Conductivewire mesh, radials, or thin aluminum sheets embedded in the composite material providethe ground plane allowing the antenna pattern (gain) to be maximized for improvedtransponder performance.NOTENote that penetration of the pressure vessel on pressurized aircraft requires additionaldata not included in this manual.The following guidance provides information to aid the installer in ensuring the most optimum location isselected for the transponder antenna.The antenna mounting should utilize the aircraft manufacturers type certificated antenna location and style.The antenna should be installed in accordance with manufacturer instructions and/or AC 43.12-2AChapter 3.Transponder antenna considerations include the following.• Be mounted away from major protrusions, such as engines, nacelles, propellers, and antenna masts• Be as far as practical from landing gear doors, access doors, or other openings that could affect itsradiation pattern• Must be mounted vertically on the bottom of the aircraft• Must not be mounted within three feet of the ADF sense antenna or any other communicationantenna• Must not be mounted within six feet of a DME antenna• To prevent RF interference, the antenna must be mounted a minimum of three feet from theGTX 3x53.8.2 GPS AntennaThe installation guidelines meet the intent of AC 20-138A Section 16. The greater the variance from theseguidelines, the greater the chance of decreased signal quality and availability. Meeting all of theseinstallation guidelines may not be possible on all aircraft. These guidelines are listed in order ofimportance to achieve optimum performance. Items 3 to 5 below are of equal importance and theirsignificance may depend on the aircraft installation. The installer should use best judgment to balance theinstallation guidelines.1. The GPS antenna should be mounted as close to level as possible with respect to the normal cruiseflight attitude of the aircraft. If the normal flight attitude is not known, substitute with thewaterline, which is typically referenced as level while performing a weight and balance check. Ashim may be used to level the antenna.2. The GPS antenna should be mounted in a location to minimize the effects of airframe shadowingduring typical maneuvers. Typically mounting farther away from the tail section reduces signalblockage seen by the GPS antenna.