Vikash, The typical design is use of coax or hard constructed coax...using large 6" or so pipes with interconductor. Normally we call these duplexers. They often have 1/4 wave length lengths being open at one end so they will look like short at source end producing a notch. But an open at the pass freq.
The reason for large pipe type construction is to reduce the R so the Q will be high and allow the pass and notch freqs to be close together. There are many designs and sources for what you are talking about. They go back over 50 years and are still being built today. If you go to www.tessco.com you can see products from a number of manufactures with the specs. One has to look at what one wants...freq spacing and the amount of notch/filtering and pass attenuation. 73, ron, n9ee/r >From: sms mms <[EMAIL PROTECTED]> >Date: 2007/08/26 Sun AM 09:00:13 CDT >To: Repeater-Builder@yahoogroups.com >Subject: Re: [Repeater-Builder] duplexer design > >I require the value of insertion loss on both frequencies. I have to design >band reject type duplexer,please suggest the design. I will be grateful. >vikash > >Ron Wright <[EMAIL PROTECTED]> wrote: Sounds as if you are designing a >duplexer with coils and caps. It is often this approach will not have a high >enough Q to have a notch at one freq and at the same time pass freq with low >enough insertion loss. > >Normally duplexers use cavities which are made from coax made from heavy metal >tubes, inter and outer conductors. Not your typical coax, but follow the same >format. > >You may have the notch on both frequencies, but what is the insertion loss at >the desired pass freq. > >73, ron, n9ee/r > >>From: sms mms <[EMAIL PROTECTED]> >>Date: 2007/08/24 Fri PM 12:11:46 CDT >>To: repeater <repeater-builder@yahoogroups.com> >>Subject: [Repeater-Builder] duplexer design > >> >>Dear all, I am Vikash Gupta from India. I am designing a duplexer having low >>frequency:230 MHz, High gfreuqency: 234 MHz. I am usingà coil with 8 no. of >>turnsà and 22 PF capacitor. I have to get Insertion loss <1.2 on both low >>and high sides. But I have a problem in getting this. I have got Rejection of >>more than 80 dB and Return loss of better than 20 dB on both sides. Please >>give me suggestion what I have to do? thanks in advance. Vikash à >> 5, 50, 500, 5000 - Store N number of mails in your inbox. Click here. > >Ron Wright, N9EE >727-376-6575 >MICRO COMPUTER CONCEPTS >Owner 146.64 repeater Tampa Bay, FL >No tone, all are welcome. > > > > Try the revolutionary next-gen Yahoo! Mail. Click here. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
