FILTER DESIGN USING COUPLING MATRIX SYNTHESIS TECHNIQUE

Abstract

RF and microwave filter is one of the essential constituents of modern communication system. In this dissertation work describe how the coupling matrix is generated for nth order filter and tells the superiority of coupling matrix filter design method over the previous present methods. Similarity transform method is discussed that provide a topology freedom in filter design using the proposed method. The concept of Stepped impedance resonator (SIR) provides size reduction and choice in harmonic frequency that can be alter by changing admittance ratio K. A novel method in SIR for harmonic suppression is used which uses cascaded SIR having different spurious frequency component so that the one spurious frequency is removed out due to effect of other one. Our proposed filter works in the frequency band for vehicular communication that is 5.85-5.925GHz. Center frequency is choose to be 5.9GHz. We have proposed two filters, 3rd order and 5th order, for the same frequency band. The third order filter shows 2.47dB insertion loss in the pass-band, more than 20dB suppression upto 15GHz and wide bandwidth which is 6%. Fifth order filter shows improved bandwidth performance which is 5%. Also, 5' order filter shows a degradation in the insertion loss and almost same harmonic suppression as the 3rd order.