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Hi Martin,

1. I was interested to know how works Duffy's published calculator for small loops. Of course, all intermediate steps of calculations with this device were unknown for me but Duffy did mention the reference source
? ? which he used to create a calculation program. I was eager to verify the results using known equitions that are published widely in various technical literature sources.

2. The Gain of antenna is defined through an equation:
? ? ?Ga = 10log 4pi +10log K +10log D + 10log A -20log wavelength of interest, the meaning of? ? parameters you can find in my previous emails.

3.? The efficiency of antenna K is a ratio of radiation resistance to sum of radiation rasistance and ohmic loss of antenna.
? ? ?So, I used R rad= 0.01 ohm and R ohmic resistance=1 ohm, just for a sake of argument for small loop antenna. The K is about 0.01? ( or 1% ), or 10log 0.01= -20 dB
? ? ?Of course, you can use other values to calculate K on your own.
? ? ?In addition, that is true for a? tuned antenna regarding the antenna efficiency factor.

4.? Now regarding any advantage or disadvantage between untuned and tuned small loop antennas using your words - outperforming.
? ? ?Yes, there is an advantage of tuned antenna due to the Q-factor that multiplies accordingly the received signal because

? ? ?Vo=E/AF and Usig=Vo x Q at receiver input when it is a condition of parallel resonance.

? ? ?Many sources say the advantage between tuned and untuned small loop antennas could be expected by 6-10 dB due to the Q-factor.
? ? ?However, we have to take everything in a proper way, considering as well as the presence of ambient noise that will be equally multiplied by the Q-factor ( Unoise ambient x Q ).
? ? ?So, the SNR will not be improved at receiver output unless the ambient noise is significantly less than the thermal noise of your receiver and we can consider only the presence of thermal Johnson noise.
? ? ?Let's take an extreme case when the direction of desired received signal and ambient noise are the same and you cannot minimize with your directional loop antenna...

Regards,

Raphael??
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