Efficiency of PCB Antenna - How to Measure !

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pcb antenna ism

How to measure efficiency on PCB antenna designed for ISM band ?
Is this parameter related to VSWR or S11 ?
Can this parameter be measured using a network analyzer?
Is out there on Internet a document showing nice and clear how to measure it?
I did some search but cannot find anything clear.
Thank you in advance!
HS
 

search on "Wheeler Cap" and you will find numerous references. I would also want to have radiation pattern, gain, s11 information., all the usual parameters.
 

It is nothing related to VSWR. Regarding the same amout of energy is delivered to the antenna, part of the energy is radiated, the other part of energy is dissipated due to resistive load and surface wave. If you are using HFSS, you can get the radiation efficency directly.

 

It is related to VSWR (and S11) but good matching doesn't necessarily mean good efficiency. Antenna efficicency depends on ohmic losses in the material (dielectric), polarization losses, and imperfect matching. So you cannot just measure S11. A 50-ohm resistor connected to the VNA would be a perfect match but it doesn't radiate. The best way is to use an anechoic chamber where you determine the antenna gain (radiation pattern).
 

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