Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics 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.

Untheoretical Frequency Change

Status
Not open for further replies.

Antenna (^.^)

Member level 3
Joined
Jul 6, 2015
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
499
I am trying to make a reconfigurable patch antenna but have trouble with simulation.

The first patch should be at 2.4GHz and then the first + second patch should be 2.1GHz.

Theoretically the frequency should decrease from 2.4 to 2.1GHz when the second patch turns on (I.e when the length of patch gets longer).
However the frequency actually increases!!!

How can I fix this?

the antenna.PNG
 

volker@muehlhaus

Advanced Member level 5
Joined
Apr 11, 2014
Messages
2,603
Helped
1,003
Reputation
2,010
Reaction score
996
Trophy points
1,393
Activity points
16,720
when the second patch turns on (I.e when the length of patch gets longer).

Is this a verified method/layout?

To me, that patch "extension" idea looks wrong. The current path/pattern is totally different from the current in a patch antenna.
 

SunnySkyguy

Advanced Member level 5
Joined
Sep 26, 2007
Messages
6,744
Helped
1,675
Reputation
3,348
Reaction score
1,644
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
50,737
How have you configured your microstrip , stubs and slots for polarization and reactive loading?

Have you considered linear and circular polarization with two near-degenerate orthogonal resonant modes with equal amplitudes and a 90◦ phase difference?
 

Antenna (^.^)

Member level 3
Joined
Jul 6, 2015
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
499
The current path/pattern is totally different from the current in a patch antenna.

Is it because of the way I have tried to connect both patches with a transmission line in between?
What is the proper way to extend?
 

Antenna (^.^)

Member level 3
Joined
Jul 6, 2015
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
499
Ah ok. Thank you for your helpful replies! :)
I have checked online about dual band patch antenna and found one similar to what I want to do:

https://slidegur.com/doc/335663/reconfigurable-patch-antenna-powerpoint
However it does not show what the current path should look like.

This is the current path of my patch model.
What could be improved about the connection to get it looking normal so the frequency will decrease?
current path of patch.PNG
 

volker@muehlhaus

Advanced Member level 5
Joined
Apr 11, 2014
Messages
2,603
Helped
1,003
Reputation
2,010
Reaction score
996
Trophy points
1,393
Activity points
16,720
The big difference between your antenna and the paper is that
- your antenna has a single connection to the extension in the center, not many distributed, and
- your antenna does not switch that patch extension on/off.
 

Antenna (^.^)

Member level 3
Joined
Jul 6, 2015
Messages
54
Helped
0
Reputation
0
Reaction score
0
Trophy points
6
Activity points
499
Oh, ok...
I changed the design to this so that the extension is distributed.
The transmission line represents a switch (pin diode) to turn the patch extension on.
But the frequency is still increased instead of decreasing?

New design.PNG
 

volker@muehlhaus

Advanced Member level 5
Joined
Apr 11, 2014
Messages
2,603
Helped
1,003
Reputation
2,010
Reaction score
996
Trophy points
1,393
Activity points
16,720
But the frequency is still increased instead of decreasing?

You started with a resonance at 2.4GHz, and the frequency has moved down to 1.8GHz in your plot. This is what we expect.

For the field plot, resonance frequency gives more information than plotting at 2.4GHz (where you have no resonance with these dimensions).
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top