Ultra-Compact Dual-Band Half-Mode substrate integrated waveguide filter and filtering power divider based on metamaterial concept

Abstract

In this paper, a novel dual-band (DB) half-mode substrate integrated waveguide (HMSIW) filter and three novel equal/unequal DB HMSIW filtering power dividers (FPDs) based on the metamaterial concept with ultra-compact dimensions are proposed. The working principle of the proposed configurations is based on the theory of evanescent-mode propagation. Based on the metamaterial concept, a novel compact metamaterial unit cell with double negative permittivities by combining two different types of metamaterial unit cells has been introduced. By loading the proposed metamaterial unit cell with dual negative effective permittivities at different frequencies on the HMSIW surface, two forward passbands have been generated, independently. These two passbands are located below the waveguide cut-off frequency of the dominant mode in the HMSIW structure, which have been designed for WiMAX and WLAN applications. The resonance frequencies of each metamaterial unit cells can be arbitrarily regulated. Accordingly, by resizing the dimensions of each unit cells, the center frequencies of the introduced unit cell could be separately controlled. Four different techniques have been utilized to reduce the size of the proposed devices, which are the evanescent mode technique, HMSIW technique, meander technique, and fractal technique. To illustrate the performance of the proposed structures, the designed dual-band filters (DBFs), and equal DB FPD have been fabricated and measured. A reasonable agreement between simulated and measured results has been achieved. The total size of the proposed HMSIW DBF and FPD is about 0.10 λg × 0.10 λg. The proposed devices have many advantages in terms of compact size, low insertion loss, high selectivity, easy integration with the other planar circuits, and flexible bandwidth allocations.