Another tool I've found indispensable for setting up and troubleshooting phased
vertical RX arrays is a two-port VNA. I use an Array Solutions VNA-2180 (now
discontinued) for critical measurements. I also have a NanoVNA H4
(https://nanovna.com/) which is a very "affordable" VNA that can be used as a
portable, handheld, standalone instrument and that you can take out in the
field. In most cases, the NanoVNA H4 is more than good enough.
There is a learning curve to using a VNA. However, once you learn it, you'll
be able to make very accurate measurements of delay line lengths, preamplifier
gain and phase, phase combiner gain and phase. Most VNA's also have a TDR
function, although it is usually based on frequency domain measurements that
are transformed to the time domain.
I'm running a homebrew RX array and it would have been almost impossible to get
it running as well as it is now without a VNA.
73, John W1FV
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