The AQRP Vector Impedance Analyzer, kit #25 towards the bottom of this webpage:
? ??
does something similar, but at audio frequencies.?
K5BCQ also did the AGC and PopFix kits for us.
Drives the antenna with a square wave? from an si5351 at the target frequency, detects the
voltage and current at the antenna port using two SA612 mixers with a local oscillator
that is 4khz away?from the target frequency.? The two resulting audio channels (for voltage
and current, relative phase is important) are digitized and inspected by DSP algorithms
on an ARM processor.? The algorithms filter the 4khz audio for inspection, discarding?
all the crud due to harmonics and other random signals.
The W5BIG AIM VIA does much the same thing, and comes with a very clear description:
? ? ?
Used DDS chips because the precise PLL tuning at reasonable cost offered by the si5351
and friends was not yet available.??
The AQRP VIA has managed to extend the technique for use as a 2 port network analyzer.
And uses si5351 harmonics to operate up through 440mhz, similar to your creation.
Jerry, KE7ER
