Miniaturized and Selective Half-Mode Substrate Integrated Waveguide Bandpass Filter Using Hilbert Fractal for Sub-6 GHz 5G Applications

The present paper proposes a novel miniaturized and selective half-mode substrate integrated waveguide (HMSIW) bandpass filter (BPF) using Hilbert fractal geometry. A non-uniform horizontal periodical DGS (HPDGS) is introduced in the ground plane to miniaturize it further and obtain wide and steep outband rejection to enhance the filter's performance. A three-pole bandpass filter (BPF) with a center frequency of 3.5 GHz is simulated, analyzed and designed on a low-cost substrate FR-4 (epsilon(r) = 4.4). The filter becomes small, shows the low insertion loss of 1.1 dB and return losses of more than 16 dB, and is appropriate for operation from 3.38 to 4.20 GHz spectrum considered for the lower band fifth-generation (5G).