designing a microstrip dual-band bandpass filter (bpf) with suitable isolation between two passbands

this paper presents a new design for a microstrip dual-band band-pass microstrip filter (bpf) with suitable isolation between two passbands. in this design, a basic structure is used to achieve a desirable frequency characteristic in the passband. in this regard, defected ground structure (dgs) is implemented to reach optimum parameters of the filter such as bandwidth, return loss, insertion loss. the special features of the filter are the compact size, dual-band design and suitable isolation between two passbands. variation of the filter characteristics is compared in a table before and after applying dgs. simulation results are at frequency of 4.84ghz and 3.8ghz. return loss of -20db and - 25db and insertion loss of -0.5db and -0.9db are the results of the mentioned frequency, respectively. also the bandwidth of 87 mhz is achieved for both simulation frequencies. simulation results are well-matched to the characteristics of the fabricated filter