ADS-B diversity in AK, HI being considered?

[dgger]

The DA42 fuselage is made of carbon fiber

All DA42 or just newer ones?

Mine from 2008 was pretty good at shielding anything RF. So I suspect most all if not all of them.

[CFIDave]

All DA42/DA62 wings and fuselage are predominantly carbon fiber, in contrast to the DA40 that's almost exclusively made of fiberglass (with just the wing spar caps and "roll cage" around the cockpit being carbon fiber).

[Rich]

All DA42/DA62 wings and fuselage are predominantly carbon fiber, in contrast to the DA40 that's almost exclusively made of fiberglass (with just the wing spar caps and "roll cage" around the cockpit being carbon fiber).

This isn't quite accurate but I figured no big deal until the light bulb went off. I'd been thinking that with my DA40 being mostly glass composite maybe the single transponder antenna below the cabin might suffice for space-based receivers. But the fact is the wing shells (top and bottom) are composed of an inner layer of glass and an outer layer of carbon fiber. Depending on what wavelengths it effects this could compromise the signal strength to a satellite constellation. It doesn't seem to affect things like VOR reception or reception, but we're talking tens of miles vs. several hundred, minimum.

[CFIDave]

Yes, wing shells (beyond the wing stubs) are partly carbon fiber in the DA40, but that doesn't affect internal vs. external antenna reception in the fuselage. The DA40 has a big advantage of being able to pass RF through its fiberglass fuselage, not shared by Diamond twins.

[Rich]

Yes, wing shells (beyond the wing stubs) are partly carbon fiber in the DA40, but that doesn't affect internal vs. external antenna reception in the fuselage. The DA40 has a big advantage of being able to pass RF through its fiberglass fuselage, not shared by Diamond twins.

I was thinking more along the lines of the potential for attenuation of the signal from the existing transponder antenna located below the fuselage. This hasn't been any problem when maneuvering around locally and examining the subsequent requested ADS-B performance report. But again, we're talking tens of miles vs. hundreds. I do know of signal-blocking due to doing some semi-steep turns causing initial failures of rebate qualification flights by those with aluminum-skinned aircraft.

If simply replacing the existing antenna with one inside the tail would be acceptable to the powers-that-be, I'd definitely take that route.

[Lou]

I have to correct a post I made above about the internal antenna approach. The internal antenna installed with my GTX 345R (W) was a combination satellite/WAAS antenna for the WAAS signal. The GTX345 uses the existing transponder antenna for outbound transmission, so no change in respect of diversity at all. The principal benefit was ease of installation, ie no composite repair.