A transition between an NRD guide, suitable for construction of high performance millimeter-wave integrated circuits, and a microstrip line, being used to mount semiconductor devices such as HEMT, HBT, and MMIC, was developed at 60 GHz. The main emphasis was placed on the manner of field matching between the NRD guide and the microstrip line. We propose adoption of this a new transition structure employing a vertical strip line, which can be easily coupled to the NRD guide, and a coaxial line connected to the microstrip line. Moreover, we applied a packaging structure with a choke circuit for the microstrip line to prevent undesired leakage between the NRD guide and the microstrip line. The insertion loss of the fabricated transition was measured to be less than 0.5 dB in the bandwidth of 3 GHz at a center frequency of 60.5 GHz. The transition was applied to MMIC amplifier integration in the NRD guide at 60 GHz. The forward and reverse gains were measured to be 15 dB and -20 dB, respectively, at 60 GHz.

A mode transformer between the NRD guide and the vertical strip line was developed and applied to the right angle corner, T-junction, and 3-port junction at 60 GHz. Emphasis was placed on a fully CAD-based design procedure by using an electromagnetic field simulator. Agreement between the simulated and measured performances of the junction circuit was obtained, and thus the validity of the design procedure was confirmed. A well-balanced transmission coefficient of the 3-port junction, found to be 4 0.5 dB, was observed in the bandwidth of 2 GHz around a center frequency of 60 GHz.

A high permittivity LSE-NRD guide was applied to a planar antenna at 60 GHz. Emphasis was placed on compatibility between the high permittivity LSE-NRD guide and the conventionally used low permittivity LSM-NRD guide. Performance of the transition between two such types of NRD guides was optimized by using an electromagnetic simulator and the validity was experimentally demonstrated. A simple radiator, consisting of a tapered high permittivity LSE-NRD guide was fabricated and evaluated as to radiation characteristics. Since the radiator has a broad radiation pattern, it was employed in a primary radiator of a two-dimensional parabolic reflector to develop a new type of folded planar antenna at 60 GHz. This planar antenna has a double-layered structure. In the upper layer, a metalized dielectric substrate with a slotted array is excited by a rectangular-shaped oversized waveguide, and in the lower layer, an offset parabolic reflector is fed by the radiator. Measurement showed the half-power beam width of the fabricated antenna to be 2.5 degrees in the E and H planes, respectively, and the gain to be 35.3 dBi, thus indicating that a good pencil beam antenna was successfully developed in this manner.