psychose
Filing Flight Plan
- Joined
- Oct 15, 2019
- Messages
- 2
- Display Name
Display name:
psychose
Some of you may be aware of NavCanada’s intent to provide space-based ADS-B services in the near future. This will require a transponder antenna able to transmit above the aircraft. US pilots flying to Canada and Canadian pilots flying to the USA will thus require an antenna system able to receive both spaced-based and ground-based signals. Diversity transponders, which can receive and transmit on two antennas simultaneously, are required and are quite expensive. I am wondering if it would be possible to build a powered «signal doubler» allowing a regular transponder to receive/transmit on two antennas simultaneously.
Even if this is possible, my RV8 offers few places where a regular ball/stem antenna can be located on the upper surface. Perhaps under the fiberglass fairing on the top of my vertical stab, however this position offers minimal ground plane in the lateral direction, the vertical stab being about 2 inches wide. My calculations from Jim Weir's website shows that a minimum radius of 2.3 inches (4.6 inches diameter) is required. I could also install in the engine compartment, under the fiberglass cowling (while I don't mind having this little antenna under the belly, seeing it on the top surface kind of ruins the esthetics... would rather have it concealed).
A better solution may be a single antenna placed in a position where it can transmit both upwards and downwards. This is what uAvionix is proposing with a future version of their tail mounted Tailbeacon ADS-B antenna system. In this case, what engineering design features allow them to significantly reduce/eliminate the antenna’s ground plane? Is this something an amateur builder could reproduce inexpensively?
Appreciate any thoughts and ideas from those of you skilled in similar electrical/avionics issues. I’m sure both Canadian and American owners would appreciate this, especially if a simple and inexpensive solution can be found.
Normand
RV8 C-GNGN
Even if this is possible, my RV8 offers few places where a regular ball/stem antenna can be located on the upper surface. Perhaps under the fiberglass fairing on the top of my vertical stab, however this position offers minimal ground plane in the lateral direction, the vertical stab being about 2 inches wide. My calculations from Jim Weir's website shows that a minimum radius of 2.3 inches (4.6 inches diameter) is required. I could also install in the engine compartment, under the fiberglass cowling (while I don't mind having this little antenna under the belly, seeing it on the top surface kind of ruins the esthetics... would rather have it concealed).
A better solution may be a single antenna placed in a position where it can transmit both upwards and downwards. This is what uAvionix is proposing with a future version of their tail mounted Tailbeacon ADS-B antenna system. In this case, what engineering design features allow them to significantly reduce/eliminate the antenna’s ground plane? Is this something an amateur builder could reproduce inexpensively?
Appreciate any thoughts and ideas from those of you skilled in similar electrical/avionics issues. I’m sure both Canadian and American owners would appreciate this, especially if a simple and inexpensive solution can be found.
Normand
RV8 C-GNGN
