Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to measure Axial Ratio from 2 Circular polarized antennas?

Status
Not open for further replies.

ateet101

Newbie level 6
Joined
Jun 8, 2015
Messages
12
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
112
I have created two circular polarized antennas and was wondering how I can measure the Axial Ratio using the network analyzer? I have already modeled it in CST, but I need to record real-time data I know how to measure it if I have a linear polarized antenna. I just change the orientation 90 degrees out of phase and take the min and max. The problem is that I dont have a linearly polarized antenna.

I need to measure S21's and calculate the axial ratio
Thanks
 
Last edited:

zorro

Advanced Member level 4
Joined
Sep 6, 2001
Messages
1,131
Helped
356
Reputation
710
Reaction score
298
Trophy points
1,363
Location
Argentina
Activity points
8,902
Are they two identical antennas whose axial ratio you want to know?
Or one of them is the antenna under test and the other is a reference (almost perfect) CP antenna?

Z
 

ateet101

Newbie level 6
Joined
Jun 8, 2015
Messages
12
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
112
one of them is under test and the other is a reference
 

zorro

Advanced Member level 4
Joined
Sep 6, 2001
Messages
1,131
Helped
356
Reputation
710
Reaction score
298
Trophy points
1,363
Location
Argentina
Activity points
8,902
Just an idea:
As the reflection in a perfect conductive plane changes the hand of an eliptical polarization, I think you can perform this test:

a) Point the antennas directly and measure s21a.
b) Point the antennas through a perfect reflecting plane and measure s21b.

One of the measurements gives a value higher than the other (which one depends on whether the antennas are of the same or opposite hand).

|s21a| and |s21b| should be sufficient for calculate the axial ratio.

Notes:
The path length must be the same in both measurements
The direct path in b) must be highly attenuated (keep the antennas away, eventually use absorbers, etc.)
Reflected paths in a) must be highly attenuated
The plane must be "big" (ideally infinite)
The antennas should be in far field
The reflection angle is not of main importance
It is supposed that the reference antenna has axial ratio 1

Regards

Z
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top