Interesting... thanks for the information. Yes, as you are aware, the
TIS delay can cause significant change in apparent direction when the
target is at close range. A moments reflection, however, will show
that (except for aircraft doing substantial maneuvering) this is not a
big problem.

My concern about shadowing of the antenna remains. Even the high
dollar SkyWatch with TWO externally mounted antennas has significant
shadowing problems. As for shadowing "behind and below you" - one
plane climbing or descending into the other in the traffic pattern is
probably the most common mid-air scenario.

Regardless, this sure looks promising - and at a price about 1/5th of
the competition.