Antenna Location Questions

Scott DellAngelo · #1 09-04-2005, 07:16 AM

I am trying to figure out where to mount antennas. At Oshkosh I saw eveything from antennas basically right next to each other, to spaced all over the airplane both top and bottom. I will have marker and nav antennas in the right tip. ELT is mounted on the aft side of the roll bar (tipup). GPS will be on the glareshield. That leaves the two that poke out, com and transponder. I read in the rv-list archives that you "should" have 3 feet seperating them (even though clearly at Oshkosh I saw some well inside that distance and people said they work fine). I also saw at Oshkosh some people mounting antennas just aft of the firewall and also very popular to have them just in front of the spar center section. I just measured and it looks like I could put one just aft the firewall, next to the fuel vent. I could put the other one on the opposite side in front of the spar. that would give a 3 foot spacing but I would be close to the gear weldment in one direction and the firewall in the other. Any other ideas other than to suck it up and put one back of the baggage bulkhead?

Thanks,
Scott
#90958 Finishing
N598SD reserved

gmcjetpilot · #2 09-04-2005, 09:13 AM

Provide as much spacing as PRACTICAL. Obviously there are ideals, but I doubt being closer than 3 feet will make any difference or at least a difference you will ever notice. The transponder on the belly, center just aft of the firewall and the Com antenna just fwd of the rear spar, off center, worked for me. G

osxuser · #3 09-04-2005, 10:25 AM

Transponder can be the DME type (Chip) antenna. The thing to look for mounting this antenna is be sure that no part of the airplane will shade it from radar in climb cruise or decent. Therefore it's best to locate it near the center of the bottom of the fuselage. The com on the other hand, usually doesn't care as much where you put it. I'd place it up closer to the front or even on the top. If you have two coms it's sometimes beneficial to put one on the top and one on the bottom. The Top goes to com2 (mostly useful for better ground transmissions, talking to FSS and such) and the bottom to com1 for if you have trouble with picking someone up at approach or something.