[FoxHunt] TDOA questions.

[w9jdh at netzero.net]

Good morning Kurt. I have built and used various types of equipment since the late '80s thru a couple of years ago when gasoline prices wet through the roof. As to the specific spacing, I personally reccomend keeping the spacing/wavelength fairly close for best performance. This is particularly critical when using antennas that are phased and 2 elements are used. I use the formula 234/f in MHz x velocity factor of the phasing line (usually .66 for RG-58u). I can tell you that this particular antenna works with or without using TDOA.
A 2 element phased antenna will have very distinct nulls perpindicular to the boom, and located in the center of the boom. The drawback to this though is that the nulls will be on both sides of the boom.
 
To answer your question though, I would say to used this antenna on both 2m/70cm, the pattern will change, but to what degree I can't say.

I highly reccomend the book 'Transmitter Hunting/RadioDirection Finding Simplified' by Robert Moll. I would say this book has the information on just about every aspect of amateur radio RDF.

I hope this helps some.

73,
Jimmy,  W9JDH