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All,

I am wondering whether those who spend a lot of time building and testing small loop antennas besides Owen Duffy's concept of SNR degradation? are familiar as well as with Steven R. Best's research? work "Optimizing the Receiving Properties of Electrically Small HF Antennas" published in 2016 ? This article can be found on? site ?.
He describes how the mismatch loss between antenna and receiver effects receiver sensitivity and noise figure for both small dipole and magnetic loop antennas.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Everyone knows it is very challenging task to minimize mismatch loss factor for small receiving antenna.
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? I guess in Duffyy's concept the mismatch loss is not taken into consideration at all because he operates with Antenna Factor only where just a straight "conversion"? between free space impedance value 377 ohms ( the far zone of transmit radiation)?to receiver input impedance of 50 ohms is admitted ( that follows the a classic equation for Antenna Factor definition ).?
However, we should deal with Mismatch Loss = 4 Ra x Rl / | Za + Zl|^ 2? , where Ra - radiation resistance plus ohmic loss of loop, Rl - active resistance of receiver input, Za - antenna impedance and Zl - receiver input impedance.

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Mismatch Loss = 1 - |Г|^2 , where?Г - reflection coefficient from receiver input can be expressed differently as well.
In other Duffy's published articles about small loop antennas I found that he neglects Ra due to a small value considering only La - antenna inductance.? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? So, there is no mismatch loss ( almost zero value) and therefore,? the reflection coefficient Г=1, meaning an open circuit...

Although in other article he ( Owen Duffy ) states the maximim received power from antenna to receiver will occur when Xa = Rl for loop antenna, where Xa -reactance of antenna caused by La inductance.?
Does it fit with ealier shown equation for the mismatch loss ?
?

Regards,
Raphael?