IEEE Microwave and Wireless Components Letters

We demonstrate 60 GHz carrier generation and transmission using a two-mode injection-locked Fabry-Perot (F-P) slave laser. The relationship between the power of the generated carriers and the frequency of the reference signal for the injection-locking is also investigated. The RF power-penalty caused by fiber dispersion was within 2.0 dB when the locked modes were transmitted at a distance of 0.5-... View full abstract»

This paper presents a high yield, ultra compact, low loss phase shifter MMIC, realized with a commercial 0.6 μm GaAs MESFET process. Phase shift is enabled by varying the varactor capacitances of the lumped element equivalent of a transmission line. Continuously adjustable phase control over 90/spl deg/ is achieved from 4 GHz up to 6 GHz, with a loss of less than 2.2 dB. At 5.2 GHz, a loss... View full abstract»

The performance is reported for a new microelectromechanical structure (MEMS) cantilever microswitch. We report on both dc- and capacitively-contacted microswitches. The dc-contacted microswitches have contact resistance of less than 1 /spl Omega/, and the RF loss of the switch up to 40 GHz in the closed position is 0.1-0.2 dB. Capacitively-contacted switches have an impedance ratio of 141:1 from ... View full abstract»

A new model of the second- and third-order intermodulation products from HEMT and MESFET small-signal amplifiers, resulting from nonlinear drain-source current has been proposed in our previous publications. Based on this model, intermodulation nulling conditions in terms of the Taylor series coefficients, hence in terms of bias, have been investigated. This paper now examines the load dependence ... View full abstract»

A two-layer frequency selective surface (FSS) is used as a very compact and lightweight transverse waveguide filter element. A narrow-hand transmission response is produced from two layers, which, otherwise, in isolation would exhibit a broadband response. Measured results are compared with theoretical data obtained from a Transmission Line Matrix (TLM) based modeling method. Reduction in the pass... View full abstract»

A new calibration approach is described for phase noise measurements of free-running voltage controlled oscillators using the injection locking technique. The injection locking technique allows the locking of free running oscillators to a reference over a wide bandwidth during a phase noise measurement. Compared to conventional phase noise measurement techniques, the injection locking technique in... View full abstract»

A simple yet rigorous method has been developed to enable the loss tangent of dielectrics, having a known relative permittivity, to be accurately measured using a waveguide resonant cavity. The novel method eliminates the need for any physical measurement, either on the cavity or dielectric sample under test. The only electrical parameters that need to be measured are resonant frequencies and Q-fa... View full abstract»

The transverse resonance method is used to evaluate the effective dielectric constant of a material present in the form of multiple slabs that partially fill a waveguide cell. It is shown that the commonly-used linear relationship for the effective dielectric constant of a mixture of dielectrics holds good to better than 1% accuracy only when the slabs are, in general, of a width each less than 5%... View full abstract»

This letter presents the design and measured performances of a microstrip 4:1 unequal Wilkinson power divider. The divider is designed using the conventional Wilkinson topology with the defected ground structure (DGS). The DGS on the ground plane provides an additional effective inductive component to the microstrip line. This enables the microstrip line to be realized with very high impedance of ... View full abstract»

Two branch-line (BL) couplers based on finite-ground coplanar-waveguide (FGCPW) structures are proposed. The first one uses the bended structure to reduce the size of the normal quarter-wavelength two-arm BL coupler. The second one improves the bandwidth by adding external compensated networks, which are also folded for size reduction. In this study, the performances of these BL couplers are exami... View full abstract»

We present a computationally efficient and robust image reconstruction algorithm for breast cancer detection using an ultrawideband confocal microwave imaging system. To test the efficacy of this approach, we have developed a two-dimensional (2-D) anatomically realistic MRI-derived FDTD model of the cancerous breast. The image reconstruction algorithm is applied to FDTD-computed backscatter signal... View full abstract»