Slotline antenna with non-leaky coplanar (NLC) waveguide feed

Aperture antennas such as slotline and loop antennas have been utilized in the microwave and millimeter wave application. In some applications, as unidirectional antenna radiation is preferred, conductor backing is adopted. But the presence of conductor backing may deteriorate the circuit performance due to the energy leakage, an inherent problem of conductor-backed uniplanar circuits. In such a case, the non-leaky coplanar (NLC) waveguide using a multilayered structure is favorable. Two multilayered structures can be used and one with an additional bottom layer is discussed as an example. Uniform guided wave structures, i.e., feed waveguide and slotline, are analyzed first using the spectral domain approach to make sure that both of them are non-leaky in the working frequency range. The entire structure is analyzed by the FDTD method.