An Integrated Millimeter-Wave Broadband Microstrip-to-Waveguide Vertical Transition Suitable for Multilayer Planar Circuits
An integrated broadband vertical microstrip-to-rectangular waveguide (RWG) transition at Ka-band is presented. This transition is especially suitable for multilayer planar circuits, by utilizing a section of multilayer three-dimensional (3-D) stepped substrate integrated waveguide (SIW) structure, along with a taper transition. A simplified initial transition model from 3-D stepped SIW to waveguide is first optimized, thereafter, a full microstrip-to-waveguide transition is constructed and further optimized. For demonstration, some back-to-back transition prototypes are fabricated by multilayer PCB processing. The experimental results show that the return loss better than 15 dB is obtained from 33 to 36.7 GHz, with the minimum net insertion loss about 0.7 dB for a single transition at 35 GHz.
A Broadband Magnetic Coupling Microstrip to Waveguide Transition Using Complementary Split Ring Resonators
A novel broadband microstrip to waveguide transition is proposed in this paper. A microstrip circuit is inserted into a waveguide along the axis of the broadside wall, and the referred waveguide is WR-90 standardized rectangular waveguide. The microstrip circuit consists of a pair of symmetric step-like patches, a microstrip probe, and a metal ground plane. The transition has a smaller size as it is end-inserted. Meanwhile, the traditionally stepped metal ridge in the waveguide is replaced with bistratal symmetric patches, integrated design of patches, and microstrip probe. Therefore, the welding loss and structural instability have been avoided. Complementary split ring resonators are loaded in the patches to broaden the bandwidth and increase efficiency. Measured results show that the proposed microstrip to waveguide transition achieves a −15 dB return loss with the bandwidth of 8.65–12.33 GHz, and its insertion loss is better 0.5 dB over the band of 8.13–12.13 GHz. Furthermore, this design features lightweight, low cost, and simple processing methods.
Double-Layer Full-Corporate-Feed Hollow-Waveguide Slot Array Antenna in the 60-GHz Band
In order to achieve a wide bandwidth characteristic of high gain and high efficiency antennas, a double-layer hollow-waveguide slot array is proposed, where a full-corporate-feed waveguide is arranged in the lower layer. This antenna can be built up easily by the process of diffusion bonding of laminated thin metal etching plates, which has high precision and is possibly a low cost technique. The radiating elements and the feed waveguide are designed to suppress the reflection over a wideband. The predicted bandwidth of the reflection less than -14 dB is 8.3% for a 16 × 16-element array antenna. A test antenna is fabricated in the 60-GHz band, and about 80% antenna efficiency with more than 32 dBi is achieved over 4.8 GHz.