Design of a 12 GHZ BPF

[fearass]

Hello Guys i have to build a micro-strip bandpass filter and i know nothing about micro-strip and what is it different from normal bandpass filter design
the filter have 12 Ghz center frequency
and 1 Ghz-2Ghz of BW input and output impedance of 50 ohms
any help would be appreciated anything like books programs hints
i have a 12.5-13 GHZ hairpin micro-strip filter already done(with its S parameters) as a hint from the professor i don't know how i can use it ?? thanks in advance

 

[biff44]

Some practical ideas:
at 12 ghz, you will need fairly tight control of line widths and gaps. I would recomment doing the filters on alumina ceramic substrate, perhaps 15 or 20 mils thick.

Hairpins are good for small space. But the easiest is simple λ/2 resonator parallel coupled line filters with an odd number of quarterwave sections.

 

[fearass]

thanks for the help man
any reference om how to build such a filter ??

 

[G0HZU]

If your professor gave you a PCB layout (artwork) of his narrow filter then the quick and dirty way to get a wider version of his filter is to take his design and slightly decrease the gaps between the hairpin sections. i.e. squish them closer together so the overall filter length is shorter. Closer coupling will give a wider bandwidth.

If you then end up slightly off centre frequency then add or remove a bit from the ends of the hairpin legs.
As the professors filter is so close to yours (apart from being narrow bandwidth) you are almost home. Just squish it until you get your bandwidth!

Not sure if you will get good marks for this approach but it is the quickest and the easiest! It shows you understand the relationship between spacing and bandwidth as well.

 

[tony_lth]

AWR simulation is very good for BPF design at 12GHz.
You can look for the exapmles of AWR.

 

[David.D]

You can try "Dual Behavior Resonator (DBR) Filter".

References:

IEEE Xplore - Narrow bandpass filters using dual-behavior resonators

IEEE Xplore - Narrow bandpass filters using dual-behavior resonators based on stepped-impedance stubs and different-length stubs

**broken link removed**

https://www.edaboard.com/threads/125024/

 

[rnusair]

Hello Guys i have to build a micro-strip bandpass filter and i know nothing about micro-strip and what is it different from normal bandpass filter design
the filter have 12 Ghz center frequency
and 1 Ghz-2Ghz of BW input and output impedance of 50 ohms
any help would be appreciated anything like books programs hints
i have a 12.5-13 GHZ hairpin micro-strip filter already done(with its S parameters) as a hint from the professor i don't know how i can use it ?? thanks in advance

ANY idea hoe to do it beside the wizard thing?

 

[BigBoss]

You can request NuHertz Filter Design Program from www.nuhertz.com for evaluation.
It's really good program, it synthesis lumped and distributed filters and generates layouts too.I have observed that designed filters have very close measurement results.
You must then simulate this filter by aid of an EM simulator like Sonnet ( free student version can be available www.sonnetusa.com) ADS Momentum or similar planar EM simulator.
You can also use Filter Wizard of AWR or ADS.
If you intend to learn the theory of these kind of filters, read some books about Planar Filters and Coupling Structures.
There are tons of materials on the internet.