Antennas

Mounting Instructions

• Summary of Rules
  • GPS antenna
    • 2 feet min from COM antennas / transmitting antennas, better 3 feet
    • 6 inches from other GPS antennas and multiple GPS antennas not in a straight line front to rear, rather offset left and right
    • no shadowing, far away from tail
    • level
    • at least 3 inches back from windscreen
    • 8 inch diameter ground plane
  • COM antenna
    • needs 18 inch square ground plane
    • 6 feet from other COM antennas / transmitting antennas (e.g. DME) for best performance, 3 feet minimum to prevent damage of COM receiver
    • far away from ELT antenna
    • top and bottom placement if simultaneous transmitting is desired on two radios without interlock
    • 1 foot from persons (Canada rule)
    • 1 foot from any protruding metal surface (gear leg, vertical stabilizer)
    • far from GPS antennas
  • Transponder / ADS-B antenna
    • 6 feet from other transmitting antennas
    • 3 feet from receiving antennas
    • far from access panels / doors
    • 3 feet minimum cable length to the transponder unit
    • 3 inches from any protruding metal surface (gear leg, vertical stabilizer)
  • Radar Altimeter antenna
    • Should be near the pitch and roll center of rotation to minimize altitude change during maneuvers close to ground
    • Must be within 6 degrees of being horizontal during flight
    • At least 20 inches from ground when parked
    • No obstructions within 120 degree cone
    • Far away from other antennas (not spelled out, but generally 3 ft from receiving and 6 ft from transmitting antennas ideally)
• EAA Videos
  • Antenna Placement
  • Antenna Drilling Holes
  • Antenna Installation
  • Archer VOR Antenna Installation
  • Traditional VOR Antenna Installation
  • Antenna Coax Connectors 1
  • Antenna Coax Connectors 2
  • ELT Installation
• Doubler Plates
  • See chapter 23 of the Garmin G3X Touch installation manuals for GPS doubler plate templates
  • Garmin sells the GA56 GPS antenna as kit which includes the doubler plate
  • The GA35 GPS antenna does not include a doubler plate
  • The Comant antennas don't include doubler plates
  • Stainair Garmin GA-35 / GA-55 / GA-56 GPS Antenna Doubler
  • Steinair Garmin GA-57X GPS/XM antenna doubler
  • Garmin GA-35 / GA-55 / GA-56 GPS Antenna Doubler (Part 115-00846-10)
  • Steinair Comant CI-121 Bent Whip Antenna Doubler
  • Steinair Comant CI-105 DME Transponder Antenna Doubler
  • Garmin does not provide a template for a doubler of the new GHA-15 Radar Altimeter. Builders show possible patterns here and here
• Installation Manuals
  • Garmin GA35 GPS Installation Instructions
  • See the Garmin G3X Touch installation manual for GPS, VHF, Radar Altimeter antenna location considerations
  • see page 115 of the AFS ACM installation manual for RV-10 specific antenna placement
  • See also paragraph 603 (page 98) of AC43-206 part 2.

Antennas

Garmin GPS antenna for G3X	GA56 (BNC connector) (not included with G3X) "kit" contains doubler plate
Garmin GPS antenna for certified GPSs (GTN650, GNX,...)	GA35 (TNC screw-on connector) (GPS price might include antenna or not, check with vendor, Sarasota includes it)
Transponder / ADS-B antenna Needs to include 978 to 1090 MHz range	Comant CI-E05 (experimental version of CI-105)
VHF top antenna (works better for ground communications)	Comant CI-E21 (experimental version of CI-121)
VHF bottom antenna (works well when airborne but not necessarily on ground)	Comant CI-E22 (experimental version of CI-122)
VOR/GS antenna	"Cat Whisker" antennas (for top of VS or bottom of tailcone), e.g. AV-12L (low profile antenna, Spruce Part# 11-05847) or AV-532L (sturdier body, Spruce Part# 11-05101) Archer VOR ANT LT Model 1 (Spruce Part# 11-21015-1, but different order number for left and right, please check)
ELT antenna	(whatever comes with your ELT)
Marker Beacon antenna	Rami AV-64
Radar Altimeter	Garmin GHA-15, see also page GHA-15.

Example of Bob Archer NAV / Glideslope Antenna mounted in aftermarket Aveo ZipTip. Note how the outer edge of the hinge overlaps to the center line of the attachment plate.

Frequency plot of Bob Archer antenna (shows 50 Ohm and resonance in the VOR/LOC frequency range of 108-118 MHz):

ELT Antenna Placement

• ELT antenna installation is governed by 14 CFR § 91.207 and AC 91-44A: It asks for:
  • "Proper installation" (which means you need to follow the installation instruction from the ELT manufacturer)
  • "The presence of a sufficient signal radiated from its antenna" (annual test).
  • The antenna to be vertically mounted
• You may install the antenna inside the airplane if
  • The airplane skin is non conductive (the RV-10 fiberglass canopy area should be fine) or the antenna is centered behind a window of at least 12 x 12 inch size
  • You provide a ground plane for it (24 inches radius for 121 MHz!)