wideband coupler: Peaks in the response

[chandregowda]

hi,

i have designed a wideband coupler(700MHz-6000MHz) using asymmetric multisection stripline configuration. the design was simulated in HFSS and Microwave CST.

In the S-parameters response, HFSS was showing peaks at higher frequencies

after fabrication, the prototype is also showing few peaks at higher frequencies....

how to eliminate these peaks in the response?


this helps me a lot..........



thanking you
chandre

 

[VSWR]

Could be many reasons. WinRAR your project files and post here.

 

[yendori]

At least your sim matches your measured data

Your coupler is resonating. What type of board are you using?

 

[chandregowda]

hi,

No substrate board, Air as the dielectric, it is cavity type coupler.


HFSS simulations matching with measured results.

The model consists of 2 parallel coupled lines. multiple sections (N=5) are used to get more bandwidth. Each section is λ/4 long (equal length), the bandwidth is
700-6000MHz.

 

[kspalla]

Cavity may be self resonating, so check for this.

 

[chandregowda]

hi,

cavity is resonating, peaks were removed by optimizing the cavity width in simulation software. after this return loss at few points is -10dB. fabricated model also showed similar response, but a little variation.

i am trying to improve the return loss to -15dB with the addition of stubs in simulation software.

if there are any other ways to improve the return loss, pl. let me know.
Frequency of operation-700MHz-6000MHz


thank you

 

[kspalla]

Can you describe with the pictures so that we can understand or PM me the design if you do not wish to share in the forum.