Wulfsberg Electronics Division NPX136D 用户手册

SMtbd Rev. 0.01 

NPX136D Panel Mount Radio Manual 

 

Apr 23, 2004 

Page 2-3 

ENG-FORM: 805-0104.DOT

 

 

 

 

 

RF cables must be neatly terminated (solder or crimp), and tested for shorts prior to 
system check-out (not  while connected to the radio or antenna). Keep cable bends to a 
minimum at the antenna.  Avoid sharp bends in the coax cables (minimum 3" radius) to 
prevent severe reflections.  If sharp bends are required, use 90

°

 elbow adapters. 

 

Fabrication & installation of wiring harness should be in accordance with AC 43.13-1A 
chapter 11, sections 3 and 7. 
 
Grounding and bonding should be in accordance with AC 43.13-1A chapter 11, section 3. 
 
2.3.5 

To limit exposure from radio frequency fields that exceed exposure limits for people 
occupying the aircraft, install the antenna such that it is mounted; 
on a ground plane that is between the antenna and the occupants of the aircraft, or 
farther than 32 inches (80cm) from the occupants of the aircraft. 

 
Correct antenna placement and mounting is critical in order to achieve the best possible 
performance.  In general, keep all antennas as widely separated as possible and clear of 
any large airframe obstructions.   
 
Installation of the antenna should be in accordance with AC 43.13-1A chapter 2, section 3, 
chapters 5 & 6, and AC 43.13-2A chapter 3. If possible, the antenna should be located a 
minimum of 12 ft from aircraft navigation receiver antennas and a minimum of 4 feet from 
aircraft communications and ELT antennas. Be careful not to choose separations that 
closely approximate ¼, ½ or whole-number multiples of the navigation or communications 
system wavelength. 
 
Note:  Avoid any placement that puts antennas of like frequencies close together.  
 
Bottom mounted antennas will perform best in flight, but poorest on the ground during 
testing.  Antennas may be severely degraded by 'masking' effects of the fuselage or 
stabilizers, and generally give best performance when bottom mounted. 
 
To reduce interference from rotor modulation and other undesirable stimuli, any blade or 
whip antenna must be surrounded by a ground plane surface (metallic, grounded material) 
with a radius equal to or greater than the height of the antenna. Under the same conditions, 
the antenna is also much less likely to cause interference to other aircraft systems (e.g. 
coupling into audio system, fluctuations in instrumentation, etc.). Poor grounding will result 
in severe reflected power and high levels of RFI throughout the airframe. 
 
Avoid antenna locations that will become fouled with oil, water, fuel or dirt, as this will 
degrade performance.  Roof mounts (in close proximity to rotor blades) are permissible.