Substrate Integrated Antennas and Arrays

51Substrate Integrated Circuits

As shown in Figure1.49, the SINRD guide [37] is an integrated and planar struc-

ture derived from the conventional NRD guide. Similar to the SIIG case, a material

of the lower permittivity lls bilateral extents of the guiding channel. The original

way of lowering permittivity in bilateral sides of the center guiding channel is also

the airhole perforation. Absolutely, this can be made for broadband operations [38].

Besides, an SINRD guide directly through the conventional PCB was proposed

in [39], which can be realized without employing mechanical assembly as usual. It

has the conguration as shown in Figure