A questio about IE3D pattern properties of RFID antenna

[fantastic]

rfid ie3d

Just the sample of IE3D 12, the LoadedMeaderTag, it's pattern properties as following:
Frequency : 0.874 (GHz)
Incident Power : 0.0941603 (W)
Input Power : 0.00598268 (W)
Radiated Power : 0.0053095 (W)
Average Radiated Power : 0.000422516 (W/s)
Radiation Efficiency : 88.7477%
Antenna Efficiency : 5.63878%
Conjugate Match Efficiency : 44.3739%
Voltage Source Efficiency : 62.0117%
Conjugate Match Factor : 0.837576

Althoug the CMF(Conjugate Match Factor) is 0.8, which 1 means 50% of the incident power been transport to antenna, the Input Power is only 0.06(Input Power/Incident Power ) of the Incident Power . Is there any thing wrong ?

 

[jian]

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,

 

[fantastic]

Thank you very much, jian