conjugate match efficiency
Hi, fantastic:
It is not something wrong there. The properites are for different kinds of applications. The Incident Power is with respected to the Zc (or normalization impedance) you defined. It is more for typical microwave and wireless applications where you normally have a wave source.
The Conjugate Match Factor (CMF) is not related to Zc. It is a factor judging how good your antenna impedance (Za) is matching the source impedance (Zs). When CMF is 0.8375, it means that you have 20*log10(0.8375) = -1.5 dB mis-match. In some sense, the antenna is reasonably matched to the source impedance while you still have 1.5 dB room for improvement.
Again, CMF is not a factor to judge how good the antenna radiate. It is a factor judging how good your antenna matching the source impedance. When basic configuration of your antenna is fixed, the radiation efficiency is kind of similiar while you change the feed for matching.
To design a good RFID antenna, you should try to do 2 things: (1) You should try to optimize the basic shapes and configuraiton for the best radiaiton efficiency. (2) You should try to optimize the feed for the best CMF or CMF = 1 or 0 dB. If you can achieve the 2 goals, you should be able to get a good RFID antenna design.
Regards,