they serve. They must also be mounted in interference  free locations and in areas where signals can be optimally  transmitted and received. Antennas must also have the same  polarization as the ground station.  The following procedures describe the installation of a  typical rigid antenna. They are presented as an example  only. Always follow the manufacturer’s instructions when  installing any antenna. An incorrect antenna installation could  cause equipment failure. which produce noise at the radio frequency spectrum. Static  dischargers are normally mounted on the trailing edges of the  control surfaces, wing tips and the vertical stabilizer. They  discharge precipitation static at points a critical distance away  from avionics antennas where there is little or no coupling  of the static to cause interference or noise.  Flexible and semi-flexible dischargers are attached to the  aircraft structure by metal screws, rivets, or epoxy. The  connections should be checked periodically for security.  A resistance measurement from the mount to the airframe  should not exceed 0.1 ohm. Inspect the condition of all static  dischargers in accordance with manufacturer’s instructions.  Figure 11-160  illustrates examples of static dischargers. Knowledge of antenna installation and maintenance is  especially important as these tasks are performed by the  aircraft technician. Antennas take many forms and sizes  dependent upon the frequency of the transmitter and  receiver to which they are connected. Airborne antennas  must be mechanically secure. The air loads on an antenna  are significant and must be considered. Antennas must be  electrically matched to the receiver and transmitter which  1.  Place a template similar to that shown in  Figure 11-161 on the fore-and-aft centerline at the desired location.  Drill the mounting holes and correct diameter hole for  the transmission line cable in the fuselage skin. 2.  Install a reinforcing doubler of sufficient thickness  to reinforce the aircraft skin. The length and width of  the reinforcing plate should approximate the example  shown in  Figure 11-162 . 3.  Install the antenna on the fuselage, making sure that  the mounting bolts are tightened firmly against the  reinforcing doubler, and the mast is drawn tight against  the gasket. If a gasket is not used, seal between the  11-75 Figure 11-160.  Static dischargers or wicks dissipate built up static energy in flight at points a safe distance from avionics antennas to  prevent radio frequency interference.  Installation of Aircraft Antenna Systems