A new nondegenerate dual-mode microstrip patch filter structure is introduced. The
proposed filter is based on a square microstrip patch with four slots etched in symmetrical form.
Besides its simple structure, the filter has the advantages of small size and low loss. The full-wave
IE3D package is used to analyse the proposed structure. Design curves that relate the mode
resonance frequencies and fractional bandwidth against slot parameters are presented. A bandpass
filter is designed, analysed and tested at 2.15GHz. Experimental results show good agreement with
theoretical results