Hi,
I would like to investigate some electrically short antennas in the HF to VHF region (5 - 200 MHz). Specifically, I would like to measure the antenna impedances as accurately as possible, compare the results to the NEC models etc. One crucial element for which I have very little knowledge of, is accurately measuring RF voltages. Basically, I'm looking for an RF millivoltmeter design. Bear in mind that these electrically short antennas will have a high to very high, absolute susceptance to conductance ratio, which makes accurate voltage measurement more important than otherwise. The methodology I am thinking of using is outlined here:
**broken link removed**
The above link, is part of webpage where Jim Tregellas VK5JST, gives details of his Aerial Analyser: **broken link removed**
In answer to the obvious question (why don't I just duplicate Jim's circuit ?): Jim's voltage measurement accuracy relies on (1) relatively high antenna conductances & low susceptances compared to my antennas (2) using relatively high feed voltages such that diode voltage drops are insignificant; I would like to get similar results with lower drive voltages.
Thanks in advance for advice & assistance in this quest.
I would like to investigate some electrically short antennas in the HF to VHF region (5 - 200 MHz). Specifically, I would like to measure the antenna impedances as accurately as possible, compare the results to the NEC models etc. One crucial element for which I have very little knowledge of, is accurately measuring RF voltages. Basically, I'm looking for an RF millivoltmeter design. Bear in mind that these electrically short antennas will have a high to very high, absolute susceptance to conductance ratio, which makes accurate voltage measurement more important than otherwise. The methodology I am thinking of using is outlined here:
**broken link removed**
The above link, is part of webpage where Jim Tregellas VK5JST, gives details of his Aerial Analyser: **broken link removed**
In answer to the obvious question (why don't I just duplicate Jim's circuit ?): Jim's voltage measurement accuracy relies on (1) relatively high antenna conductances & low susceptances compared to my antennas (2) using relatively high feed voltages such that diode voltage drops are insignificant; I would like to get similar results with lower drive voltages.
Thanks in advance for advice & assistance in this quest.