I have a TDOA unit based on this design http://theleggios.net/wb2hol/projects/rdf/tdoa1.htm
used with a handheld and portable antenna
However, I have the opertunity whilst adding permanent mounts to my car, to add a pair of Panorama M8 antenna mounts. These do not have any 'normal' antenna use intended for them, and I can position these either side of the roof, accurately measured and with identical whips, I also have the oppertunity to cut the feed coax for them to preceise electrical 1/2wave, allowing me to use just one set of PIN diodes.
I cannot see any problem with using such a fixed antenna system with the TDOA unit, but before i take the plunge and drill two extra holes, has anyone done this before who can offer any advice or hints?
I appreciate that such a system will give me a direction indication relative to the vehicles direction of travel