antenna-theory.com

[anthonyhfhong]

I am new to this forum. I'm testing UHF RFID System with a Reader, several Antenna & Transponders. I could calculate/estimate the RF Power transmitted to the field based on vendor's calculation spredsheet, but I wanted to verify the actual RF power at the field.

Could anyone have the experience to use a simple tool (my budget is around USD2k+) to measure RF Power, in terms of ERP, or EIRP at 3m?

Appreciate someone could advice and recommend such tool.

[Schubert]

Do you have access to a VNA (vector network analyzer)? You could try to rig up some sort of S21 (2-port power transfer measurements) to get a good idea.

Otherwise...well you have a difficult problem. I can't think of an easy way to do it. Unless you calibrate your measurements with known antennas and then swap in the vendors to see how it compares.

Your problem is very valid....its very tough to get accurate wireless measurements without spending a lot of money.



VNA:
http://www.antenna-theory.com/measurements/impedance.php

S-parameters:
http://www.antenna-theory.com/definitions/sparameters.php