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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]

New passive millimeter wave circuits built on thin alumina substrate are presented. A six-port model is generated using measurement results of a 90° hybrid coupler. Good correlations between model and circuit measurements are proven. The proposed model is suitable for advanced system simulations of V-band wireless personal area networks. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2104–2108, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25377 [ABSTRACT FROM AUTHOR]

Millimeter-wave multiport transceiver architectures dedicated to 60 GHz UWB short-range communications are proposed in this paper.Multi-port circuits based on 90? hybrid couplers are intensively used for phased antenna array, millimeter-wavemodulation and down-conversion, as a low-cost alternative to the conventional architecture. This allows complete integration of circuits including antennas, in planar technology, on the same substrate, improving the overall transceiver performances. [ABSTRACT FROM AUTHOR]

In this Letter, a simplified design approach for zero-bias power detectors suited for integration in six-port receiver architectures is presented. The proposed concept uses the quadrature hybrid coupler as an effective way to improve the input impedance matching and linearity performance. The proposed solution has been experimentally validated through its implementation into a 60 GHz six-port receiver prototype to investigate its performance in detecting various M-ary quadrature amplitude modulation (M-QAM) signals. The obtained measurement results show a high accurate and linear detection responses for all investigated M-ary QAM modulation techniques (4-QAM, 16-QAM, 32-QAM). The variation in the error rates of the demodulated signals at the adjacent differential outputs is minimal (<1%), and the maximum error rate achieved does not exceed 5%. The obtained precision and linearity performances make the proposed structure highly suitable for the emerging millimetre-wave six-port receiver front-ends. [ABSTRACT FROM AUTHOR]

A new direction-of-arrival estimation method based on six-port technology is presented. In order to obtain the beam direction, the proposed circuit uses a two-channel multi-band receiver and analogue signal processing of the six-port circuit output signals. A practical approach for estimating the beam direction has also been proposed. This approach, based on the detection of the minimum magnitude of the in-quadrature output signal, avoids the necessity of computing the angle-of-arrival value. A dual-band prototype circuit was designed and fabricated. Simulation results in the S and C frequency bands are presented and discussed. In order to validate this method, measurements were carried out in the C-band. These results show a maximal angle-of-arrival estimation error of about 3%. Therefore, low-cost direction-of-arrival measurements can be performed using this new method. [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]

An improved millimetre wave microstrip power divider is presented. This circuit enhanced the conventional Wilkinson power divider (WPD) performance by adding transmission lines between the transformer arms and the resistor to reduce inherent undesirable mutual coupling. The proposed power divider design parameters show more stability over a wider frequency band compared to other valid design solutions. For comparison purposes, the proposed power divider along with the WPD are designed at 61 GHz using high permittivity thin ceramic substrate. The measurement results of the proposed circuit demonstrate improved bandwidth with high input/output matching and isolation of -15 and -24 dB, respectively, in the whole frequency band of 10 GHz. Furthermore, the excess insertion loss is reduced by 20% compared to the conventional one. [ABSTRACT FROM AUTHOR]

A substrate-integrated waveguide (SIW) broadband phase shifter is presented and studied. The phase shift mechanism is based on the synthesis of an artificial dielectric slab using an array of metallic rods in the middle of a SIW. This technique enables a large phase shift within a compact size and enhances the density of integration. As an example, 45° and 90° phase shifters are designed and showcased on a single-layer substrate at a centre frequency of 26 GHz. The amplitude imbalance between the two paths is also avoided while the phase error is less than 5° over a frequency band of 20-32 GHz or around 46% relative bandwidth. The measured return loss is found to be better than 12 dB over the whole frequency band. [ABSTRACT FROM AUTHOR]