Ultra-Compact Half-Mode SIW FPDs with Arbitrary Power Division Ratios Using Spiral Technique

Three ultra-compact half-mode substrate integrated waveguide (HMSIW) equal/unequal filtering power dividers (FPDs) based on the metamaterial concept and the evanescent mode technique are recommended in this paper. The spiral technique is a well-known technique in planar microwave circuitry. By combining the spiral technique and the conventional complementary split-ring resonator (CSRR) unit cell, the complementary spiral resonator (CSR) unit cell can be achieved. The resonance frequency of the two-turns CSR unit cell is half the resonance frequency of the conventional CSRR unit cell with the same size and shape. Accordingly, the electrical size of the CSR unit cell is smaller than the conventional CSRR unit cell with the same physical size. According to the evanescent technique, by loading the CSR unit cell on the metal surface of the HMSIW structure, an extra forward passband can be obtained. Therefore, three miniaturized equal/unequal FPDs with arbitrary power-dividing ratios of 1:1, 1:4, and 1:8 have been designed, simulated, fabricated and measured based on the compact HMSIW-CSR structure. A reasonable agreement between simulated and measured results has been achieved. The fractional 3-dB bandwidth of the designed equal/unequal FPDs are approximately 21 % at 2.4 GHz. The whole dimension of the proposed FPDs is about 0.06 λg × 0.06 λg which confirms the small size of the presented structures.

Ultra-Compact Half-Mode SIW FPDs with Arbitrary Power Division Ratios Using Spiral Technique Keywords:

half-mode substrate integrated waveguide (HMSIW) , filtering power divider (FPD) , complementary spiral resonator (CSR) , evanescent mode technique , and miniaturization