Polarization insensitive wide-angle triple-band metamaterial bandpass filter

Abstract

Metamaterials have attracted tremendous amount of interests owing to their tempting electromagnetic responses. Based on the metamaterials, many novel practical electromagnetic devices have been realized in the microwave, terahertz, and optical frequencies. Recently, a new type of metamaterial filter has attracted growing attention. Based on the method of hybrid multiple resonances, the metamaterial filter possesses a notable spectral-filtering capability with broad bandwidth and excellent band-edge transitions. 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 (SIW), it is shown that the filter is valid to a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations. The triple-band metamaterial BPF is a promising candidate as new filters and radomes owing to its multiband transmissions, polarizations insensitive, and wide-angle responses.