i want to design a microstrip narrow BPF at 775MHz with 10MHz bandwidth. i simulated combline and interdigital filters using genesys eaglewre but the problem with above filters are...
1.interdigital---dimensions are large(10cm)
2.combline---if the capacitors are changad from 10pF to 10.05pF,the response is changing very badly......dey r very sensitive
so which topology to use....i need a filter with minmum dimensions...plz help me......
Re: 775MHz microstrip narrow bandpass filter with 10MH bandw
Traditionally you would use tunable capacitors in a combline design. You get out your screwdriver, and tweak them up for the best response after it is assembled. So, as long as the capacitors do not drift after tuning, the sensitivity is not a big problem.
Re: 775MHz microstrip narrow bandpass filter with 10MH bandw
thank u very much for ur reply....but i want my filter on a PCB....is this possible using helical resonators and can u plz tell me what would be the approx dimensions of this helical filter
Re: 775MHz microstrip narrow bandpass filter with 10MH bandw
beaulah said:
thank u very much for ur reply....but i want my filter on a PCB....is this possible using helical resonators and can u plz tell me what would be the approx dimensions of this helical filter
If you're able to use high dielectric substrate such as Alumina, the dimesions will be smaller but quite costly.
Because of low frequency, the wavelength is quite long and therefore the dimensions might not be very practical.
You have not so much choice..
This helical filter should be in cascaded cavities with few sections.The allover dimension may be around 7cmX13cm including housing.
Hi,
Did you experienced with diverse L/C systems pls by the combline structure?
50fF as sensitivty seems me tooo bad, but Im not a UHF-MW filter expert...
I would prefer (personly) the Helicals, you can have some good types (maybe from Coilcraft?), but it must be your decision. In the "www.vhfcomm.co.uk" are some descriptions such years ago.
Here is some (German) collection: www.elektronikschule.de/~krausg/Kraus_Publications/publication.html, especialy: PUFF_Microwave_Design_Part_05.doc, maybe you can adapt it... www.ukw-berichte.de/English_index.html
regards!
K.
Hi,
Read pls my past comment on these parallel topic:
"11 Mar 2010 11:12 4ms delay line at 1GHz
Hi,
I found on the pp 345 a filter what, I think, you can use (Center frequency 985 MHz, Fractional bandwidth FBW 10.359%, 40dB Rejection bandwidth 125.5 MHz. On a 120x50x1,27mm substrat, Epsilon 10.8...