Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

how to measure UHF RFID antenna port impedance

how to measure UHF RFID antenna port impedance

how to measure UHF RFID antenna port impedance

Hi everyone,
How do I measure the complex port impedance of an UHF RFID port antenna? I have tried measuring differential port impedance using VNA with a probe, but the results do not seem to be correct.

RE: how to measure UHF RFID antenna port impedance

"using VNA with a probe" - that doesn't make much sense, can you provide more detail or a photo of your test setup?  

What was your test environment?  You can easily get unexpected results by having your antenna too near a metal surface, or more likely not having the same physical ground structure at your test fixture as you have in your application.  

Have you verified your test setup by measuring a known impedance?  

A crude technique I've used in the past is to use two identical antennas, one as source and one as receptor and then make a couple of S21 measurements with the setup and extract the parameters from there.  If you can get a decent S11 setup you'll probably get much better results though.  

John D

RE: how to measure UHF RFID antenna port impedance

In what range of frequency works your RF ID antenna?
Is the setup used by you calibrated somehow? Is there any offsets taken in consideration?
Maybe a picture  would be very helpful for us ,like zappedagain said in the above post.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close