It seems that what you're predicting - an exponentially decaying "blob" - is just what we're looking for. As long as the DUT is well fixtured, there should be acceptable consistency, unit to unit. As you've said, we should just try it. In fact, other people here have done something like this in...
My text (Microwave Engineering, P. Rizzi; and just confirmed in Reference Data for Engineers) shows cutoff wavelengths for circular guides to be half the values you gave. That is,
LambdaC (TE11)= 1.706D
LambdaC (TM01)= 1.306D
LambdaC (TE21)= 1.029D
So for 4-inch dia. stovepipe, LambdaC (TE11) =...
Again, thanks for your comments.
Yes, the small loop would present a very low impedance to the generator. Shouldn't be a problem, I think; the idea is simply to source some current to the loop which should produce a rapidly decaying (non-propagating) field in the tube.
If the tube diameter is...
Thanks for the reply. You bring up some interesting points regarding launch impedance.
We won't be using an actual waveguide launch, though, so the load impedance to the test generator won't be a function of the cavity properties vs. frequency.
At this point, we're thinking of using some...
As an alternate to a TEM cell, we're exploring the idea of using a waveguide-below-cutoff as a means of creating a controlled environment for receiver sensitivity measurements. The receiver is within cellphone-sized package and contains a loop antenna. The receive frequency is roughly 900 MHz...
