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All,Science or technical applications start with appropriate measurements and decision making Process. Look at different way, you can use a 12 inch nail connecting it with a wire to your receiver

I guess you designed this amplifier with recommended LCR equalization circuit in front of it. It is possible two capacitors in series 120 pF each together with the inductance of your transformer

I'm not a math expert, I think for enthusiasts, we just want to know the performance of the equipment, we can't really test the antenna's pattern in the standard electromagnetic shielding

Raphael ， I know that the 22M input impedance becomes 244.5 ohms, which cannot match the common 1m diameter loop. I don’t know if the early resonance is caused by the large inductance of the

Jinze, My understanding is you used mini-circuits RF transformer that has winding ratio 1:1 to connect VNA to your designed LZ1AQ amplifier with balanced input and measured Z input of your antenna

Raphael， I actually use TC1-1T+ as the input coupling of the loop amplifier to test the input impedance characteristics of the LZ1AQ amplifier I

Yep. While working for a living (I'm retired) the companies we worked for paid for the good, high end, and calibrated antennas, loops (for LF), and peripheral equipment. I presently have a small set

Dave, The pleasure stays with me… I mentioned that because Martin suggested to use a small transmitting loop antenna at some distance from a constructed receive antenna measuring with VNA S21

Thanks, Raphael! In the EMC world in which I worked and still consult, we pretty much universally use the 2D^2 / Lamda. Yes, for antennas which are small as a function of wavelength, wavelength /

Dave, Your feedline can be proprely terminated at preamp input but the input of the same feedline is not properly matched to the impedance of your antenna. Of course, when you deal with a reasonable

Another easier and more empirical approach: If you sense reasonable antenna noise (=/> 6 dB) when the antenna feedline is connected to the preamp over a properly terminated preamp input (the value on

Error be corrrected in equation *Re [ S11 ] = ( R ^2 -50 ^2 + X ^2 )/ [ ( R + 50 ) ^ 2 + X ^ 2 ]*

Jinze, Unfortunately, your response is giberish because it can be made two independent measurements of S11 parameter regarding the frequency range of interest and related either to the antenna under

Yes, due to the VNA's 50 ohm constant impedance, you won't be able to get true loop reception, but at least you can see a gain level of the amplifier, and you can scan out the input impedance of the

Unfortunately this doesn't present the same source impedance to the amplifier as that of an actual loop. You will obtain a fairly flat amplitude response, but this is just the amplifier and is not

I try to use a 1:1 voltage balun as the input coupler of the small loop amplifier, so that the gain sweep can be performed directly through the NANOVNA, and I will connect a -10db attenuator in series

Dave and Dirk, Loop/ antenna amplifier for small magnetic loop antennas ( for any small antenna ) does not serve as an impedance compensation network unless you use a non - Foster method of impedance

The best way of testing an active loop is in a Crawford Cell but only a few National Labs have big enough cells to take a 1m loop , it also costs a bit to hire. Using a small TX loop close to the RX

Since s11 is a reflective measurement (think return loss) and from the plot, it appears the loop amplifier is more of an impedance compensation/stabilization network. Dave -

Hi Dirk I don’t hink Chavdar has done that, atleast not on separate frequencies. I may be wrong. He has set up a transmitter in far field on 160m but that was for testing the delay line phased