Polarization insensitive wide-angle triple-band metamaterial bandpass filter

In this letter, we report the design, fabrication and measurement of a polarization insensitive wide-angle triple-band metamaterial bandpass filter (BPF) in the microwave frequency. The proposed BPF consists of two identical metal resonant units which have three concentric square slots separated by a dielectric layer. Experimental results show that the BPF has three distinctive transmission bands centered at frequencies 6.22 GHz, 9.46 GHz and 12.14 GHz with transmission rates of -0.40 dB, -0.71 dB and -1.40 dB, respectively, agreeing well with simulation results. By introducing the substrate integrated waveguide, the filter is valid to a wide range of incident angles for both transverse electric and transverse magnetic polarizations. The triple-band metamaterial BPF can be used as multiband filters and radomes owing to its multiband transmissions, polarizations insensitive and wide-angle responses.