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A rectangular WR12 waveguide to microstrip line (MSL) transition using a very thin high-permittivity ceramic substrate ( $\varepsilon _{r} = 9.9$ and $h = 127 \,\,\mu \text{m}$ ) is presented and analyzed. The proposed configuration uses a gradually extending metal ridge over a thin-film MSL to ensure electric field transformation, and an accurate impedance matching, while maintaining a good electrical contact, without any soldering or gluing. The fabricated prototype has been successfully tested in terms of insertion and return losses. The obtained results exhibit a bandwidth of more than 37% at −10 dB with an insertion loss of 1.5–2.7 dB, over the entire 60–90-GHz frequency band. The design simplicity and suitability for high-permittivity thin-film substrates, as well as the very broadband operation capability, enable it to be easily integrated with various planar monolithic microwave integrated circuits/miniaturized hybrid microwave integrated circuits microstrip circuits for different millimeter-wave applications. [ABSTRACT FROM AUTHOR]

In this paper, a new configuration of Tapered Slot Antenna (TSA) with improved radiation pattern is proposed and studied. This antenna is designed in the form of a substrate integrated waveguide (SIW) array with respect to side lobe level constraints. For side lobe reduction, a simple quasi-triangular distribution is proposed and is accomplished uniquely by means of 3 dB power dividers. A 12-way series feed network with T-junction is designed and demonstrated. Radiation features of the antenna array are discussed to illustrate the accomplishment of a low side lobe level (-19 dB) of the array. The proposed antenna demonstrates the ability of the SIW technology to achieve a very low side lobe in a simple, compact and planar structure. [ABSTRACT FROM AUTHOR]

This paper introduces a novel design of Butler matrix in substrate integrated waveguide (SIW) technology with wide frequency band characteristics. Butler matrices are particularly useful in advanced antenna design and characteristics such as wideband operation, power handling, manufacturing, integration, cost, etc. are typical issues to be addressed in many applications. The proposed planar 4 x 4 Butler matrix provides an interesting solution to most of these issues. Wideband operation is achieved thanks to improved cross-couplers. These components are also characterized by higher power handling when compared to E-plane couplers. The use of SIW technology enables to reduce insertion losses compared to other printed technologies, while maintaining most advantages of such technologies such as high integration, manufacturing simplicity, low weight, etc. The proposed design is fully described, from the elementary building blocks to the full assembly performances. The design is optimized for operation in Ku-band with a center frequency at 12.5 GHz. A prototype of the 4 x 4 Butler matrix is manufactured, and good performances are confirmed over 24% relative frequency bandwidth. Potential use of this sub-system in multibeam antenna design is also discussed. [ABSTRACT FROM AUTHOR]

This letter presents a new class of small-size and high performance directional coupler based on substrate integrated waveguide (SIW) technology. This type of coupler is composed of a waveguide section of four arms connected by a central junction. Quasi-optical coupler technique is realized on standard waveguide by simply inserting a slab with different permittivity in central section to act as a mirror. To make this coupler realizable in the SIW format, the air slab is simply implemented by rectangular through-hole. Characteristics of the proposed coupler with respect to various parameters are presented and discussed. A prototype at 10 GHz is designed, fabricated and measured. Experimental results show that the proposed SIW cruciform coupler has a bandwidth of more than 15% over the operating frequency range. [ABSTRACT FROM PUBLISHER]

A super-compact substrate integrated waveguide (SIW) directional coupler is proposed and demonstrated. This coupler consists of a simple cross-over of two SIW sections with two inductive metallic posts in a square junction, showing a cruciform. Attractive features including compact size and planar form make this coupler structure easily integrable in microwave and millimeter-wave planar circuits, especially in beam-forming networks. A 3-dB coupler operating at 24GHz is designed using HFSS, fabricated and measured. Characteristics of 15dB isolation and 90deg phase shift between the output and coupled ports are achieved over 18% bandwidth. Design considerations and simulated as well as measured results are presented and discussed. [ABSTRACT FROM PUBLISHER]

For original paper see ibid., vol.17, no.5, p.757-9, (2007). For comment see ibid., p.374, (2008). Our proposed coupler was developed and designed on the basis of an idea similar to the H-plane crossed-waveguide hybrid. In our design, the standard metallic waveguide scheme was replaced by the substrate integrated waveguide (SIW) technology. This technology offers a number of advantages that can overcome several constraints with respect to the standard waveguide technique. A small inventory of coupler structures with the use of standard waveguide techniques was enumerated together with the existing SIW couplers. By properly choosing a dielectric constant and a sheet thickness, a directional coupler can be designed for a given frequency. [ABSTRACT FROM PUBLISHER]