Chin-leong LIm,
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A presence of writer's tunnel vision ? C'mon, don't be silly with that! You made my morning for a good laughing that positively effects the health. There I am on same page with Martin...
In order to design or propose a dummy antenna device, especially for small active antennae, I consider the antenna and its apmplifier should be as one integrated unit, where any elements between them shall not be altered ( that impedes comparison process between various SMA designs ). For example, if there exist balun, equilizer or filter they will stay unaltered ( not requiring additional elements ).?
If you experience issue of connection an unbalanced output of your VNA to balanced dummy antenna device input, worry about that connection correction exactly between these mentioned ports.
Your suggested dummy equivalent circuitry for SMA is wrong - the series element leg shall be inductance and shunt leg capacitor. In your design it is reversed.
There are some other shortcuts but I will allow you to find them on own.
In some extent it reminds me a story when I bought inexpensive chineese made SDR finding later that front end of preselectors perform funny. I discovered issues with their design - blindly copying western design and deciding to make a quick buck selling world wide. So, I redid that SDR. Later the owner of chineese outfit ask me to mail him all made corrections. I refused that because I do not like an idea of? stealing technical patents for profiting later. Anyone can reverse engineer some electronic devices but it should stay with that person.
Since you have been designed wrongly the dummy aerial, subsequentially all? your published graphs of frequency responses for a number of mentioned SMA shall be rerun as well.
Take a minute to suppress somehow your writer's tunnel vision. Your presentation of dummy antenna is a simplistic high pass filter with one section where the cutoff frequency is about the frequency of first parallel resonance of SMA. So, your frequency graphs should show attenuation between 0 and F0 ( resonance frequency ).
In actuality, the dummy antenna shall represent a low pass filter with same cutoff resonance frequency ( when it is used? as Thevenin's circuit presentation ).? All this discussion is for a bandwidth from LF up to resonant frequency unless you want to design a broadband dummy antenna beyond the resonance frequency.
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Good Day,
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Raphael
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