How to find radiation power in HFSS

[iyyappanbala]

hi fnds
i am designing triband RFID antenna, i want to calculate read range of this antenna, i choose friis equation to find read range but i need received and transmitted power.

please help me to find that parameters

 

[flanello]

You need the minimum operation power of the chip and the power of the reader. Put these values into the extended friis equation (https://en.wikipedia.org/wiki/Friis_transmission_equation#Modifications_to_the_basic_equation).
Also put the gain of the reader and the tag antenna in the equation as well as the reflection coefficients. These values are found in the datasheet of the antennas or with HFSS. For a tag antenna, the reflection coefficient needs to be calculated with the antenna and the chip impedance after \[ \Gamma = \frac{\underline{Z}_a-\underline{Z}_c^*}{\underline{Z}_a+\underline{Z}_c}\].
\[\underline{Z}_a\] is the impedance of the antenna and \[\underline{Z}_c\] is the impedance of the chip.
The last term of friis equation with the polarisation vectors can be set to one if the antennas are equally polarized and optimal aligned. If this is not the case you have to include the polarisation loss, for example if you have a circular polarized reader antenna and a linear tag antenna you have a 3dB loss and for this you have to include "times 0.5" in the equation.
Now you can solve the equation for the distance.

 

[iyyappanbala]

hi flanello
thanks for your reply
i need transmit and received power calculation,
your recommended equation need R(distance) then how to calculate

 

[flanello]

R is the maximum read out distance, this is the value you need to calculate if you want to know the read distance.
The read range of a rfid tag depend on the reader, the reader antenna, the rfid chip and the tag antenna.
(Instead of the reader + antenna you could use the maximum allowed ERP/EIRP which depends on the frequency and the country).

If you want to know the received power of the chip in a certain distance R you solve the equation for P_r. But you need the reader power for this calculation.