Continue to Site

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.

[SOLVED] Loose Coupling for a coaxial resonator

Status
Not open for further replies.

chiques

Full Member level 3
Joined
Nov 21, 2007
Messages
168
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,298
Location
California
Activity points
2,534
I am trying to loosely couple a coaxial resonator using two copper ribbons. My line is shorted on one end as shown here: http://www.rfcafe.com/references/electrical/coaxial-resonator.htm . The lines loops are fed through a BNC to and shunted to ground near the center conductor of the coax (my dielectric is air) using a 2 port network analyzer.

Also very similar to:
http://www.amalgamate2000.com/radio-hobbies/radio/coaxial_resonators.htm

I use a set of capacitors and inductors shunted on the open end to adjust the lines frequency and Q. Problem is when I change the length of the coupling loops and with the same components I get different frequency and Q measurements. I’m questioning the validity of f & Q since the coupling alone appears to change the lines behavior.

How do I know if my coupling is optimal (‘real’)? For example, I can cut my ribbons lengths 1, 2, 5 and 10” long and they all change the Q of the line proportionally. 1” has the lowest Q where 10” has the highest Q. I’m assuming the shortest length is the loosest coupling where the 10” has the tightest coupling (much more flux is absorbed by the coupling hence lowing the Q).
 



Better performance means a good compromise between higher Q, greater rejection, less insertion loss.
 
  • Like
Reactions: chiques

    chiques

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top