Odd- and even-mode coupled-slot fin-line circuits

The odd and even modes of the fin-line coupler are excited separately in two different coupled-slot fin-line circuits. Experimental results of insertion loss and return loss of the transitions from waveguide to the coupled-slot structures are presented with guide wavelength measurements compared with those computed using the spectral domain method of analysis. The performance of a 0 dB fin-line coupler is presented and the dependence on the degree of coupling due to variations in the slot separation and coupling length are also computed.