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This paper describes the approach to reconstruct the scattering matrix (S-matrix) of a multiport network from a set of one-port measurements. Formulation of reconstruction including the use of auxiliary circuits is given to solve the S-matrix of a two-port network. The results are then used with the port reduction method for the reconstruction of an S-matrix of an n-port network. Two experimental examples of three-port reciprocal and nonreciprocal circuits are presented. Reconstructed results are shown in close agreement with the directly measured results. [ABSTRACT FROM PUBLISHER]

In this paper, a planar nine-way metamaterial power-combined amplifier implemented with microstrip grids, lumped capacitors and inductors, and power amplifiers is presented. The power-dividing/combining structure is a metamaterial lens composed of positive refractive index (PRI) material with right-handed unit cells and zero refractive index (ZRI) material with left-handed unit cells. A semi-circular interface is between PRI and ZRI materials. The infinite wavelength phenomenon in the ZRI material attains an equal magnitude and phase distribution to have an interconnection with the collinearly aligned amplifiers as a nine-way metamaterial power-combined amplifier with its input and output ports at the two focal points of a planar PRI–ZRI–PRI lens. An output power of 7.64 W with a combining efficiency of 85% is measured at 1.008 GHz. Through the field measurement to each unit cell, the dividing/combining phenomenon is experimentally verified and shown in a good agreement with simulation results. Furthermore, the graceful degradation characteristic of this power-combined amplifier is experimentally demonstrated. [ABSTRACT FROM PUBLISHER]

An analytical approach to unconditional and conditional instabilities of a three-port network is presented herein. This approach begins with inequality expressions of the input reflection coefficients \Gammain and \Gammaout of a three-port network defined at ports 1 and 2 having port 3 terminated with load \Gamma3. The requirements of the conditional instabilities are derived to show that there is a largest conditional instability region in the \Gamma3-plane as ports 1 and 2 are terminated with the matched loads. Then the explicit expressions are derived for the boundary of the conditional instability region and the maximum instability curves in the \Gamma3-plane to lead one to properly select the \Gamma3 value or design the terminating network at port 3. For the selected \Gamma3 value, the conditional instability regions in the \Gamma1- and \Gamma2-planes are also given for the design consideration of the loads at ports 1 and 2. In order to fully characterize the instability of a three-port network, the similar procedure can be conducted by treating port 1 or port 2 as the terminating network. The resulting instability expressions not only provide useful design equations but also are implemented in Agilent Advanced Design System software to enhance its computer-aided capability of the instability analysis of a three-port network, especially the microwave oscillator. [ABSTRACT FROM PUBLISHER]

S-matrix reconstruction transforms are based on two stages of matrix transformation to remove the mismatch-induced errors. Over the years, these transforms are widely used in measurements of multiport devices using a two-port vector network analyzer, especially for noncoaxial applications because high-quality matched loads are hardly accessible. In this paper, analytical error analysis of the S-matrix reconstruction transforms is performed to develop the accuracy criterion that is explicitly expressed in matrix form in terms of the S-matrix of the multiport device and the reflection coefficient matrix of the auxiliary terminations. The analytical insights in this paper can pave the way for using strongly reflecting auxiliary terminations. For noncoaxial measurements, strongly reflecting termination, such as a short-circuited or an open-circuited transmission line is more repeatable, reliable, and economical than terminations with loss like resistors. Consequently, the use of strongly reflecting auxiliary terminations is speculated to ease noncoaxial multiport measurements. [ABSTRACT FROM PUBLISHER]

This letter describes a measurement technique to reconstruct the scattering parameters of an amplifier from five one-port measured results. Formulation of reconstruction with the use of auxiliary circuits is given. The criterion in selecting the auxiliary circuit is also addressed. The reconstructed results are shown in close agreement with the directly measured results. [ABSTRACT FROM PUBLISHER]

The Array for Microwave Background Anisotropy is a 7-element interferometer sited on Mauna Loa, Hawaii. The seven 60cm telescopes are mounted on a 6-meter platform, and operates at 3mm wavelength. In October 2006, the telescope was officially dedicated and renamed as the Y. T. Lee AMiBA. During 2007, scientific operations have begun, after a long process of calibration and testing. At the time of this meeting, six clusters of galaxies have been detected and mapped via the inverse Compton scattering of the Cosmic Microwave Background radiation, also known as the Sunyaev-Zel'dovich Effect. [ABSTRACT FROM AUTHOR]

In this paper, the injection locking performance analysis of dipole antenna array with each element loaded with a two-terminal oscillator is presented. The analysis is based on the nonlinear model of oscillator and the linear model of antenna array considering mutual coupling effects. The locking range of injection signal and the array radiated power are obtained by solving an equivalent multiport network. In general, the solutions include stable and unstable solutions. The Routh-Hurwitz stability criterion is then applied to remove the unstable solutions. Numerical results show that the array performance such as frequency locking range and radiated power by taking into account the array mutual coupling effects is quite different from that of an isolated antenna element. In addition, the influence of antenna element spacing upon array locking parameters in this paper is found to be consistent with other existing theories. [ABSTRACT FROM AUTHOR]

The Array for Microwave Background Anisotropy is a 7-element interferometer to be sited on Mauna Loa, Hawaii. The seven 1.2m telescopes are mounted on a 6-meter platform, and operates at 3mm wavelength. At the time of this meeting, the telescope is under construction at the Vertex factory in Germany. It is due to be delivered in the middle of 2004. A 2-element prototype instrument has already been deployed to Mauna Loa where initial tests are underway. [ABSTRACT FROM AUTHOR]

Describes two port reduction methods, which can reduce the order of measured ports to two for microwave communication systems. Instrumentation requirements; Calibration procedure; Scattering matrix measurement.

This letter presents a circuit modeling approach to analyze the scattering parameter and spatial voltage distribution of a planar nine-way metamaterial power-divider/combiner structure. The analysis is based on the multi-input and multi-output transmission matrix method. Computation results of this nine-way metamaterial power divider/combiner are shown in good agreement with simulation results using commercial microwave circuit simulator and measurement results. [ABSTRACT FROM PUBLISHER]

Describes the principle of operation, calibration procedure and experimental results of a wideband six-port polarimetric measurement system. Principle of operation; Calibration procedure; Presentation of the experimental results; Conclusions.

Discusses the development of a circuit model representing input admittance of an antenna array based on Twerky's algorithm of multiple scattering analysis. Background on electromagnetic compatibility; Features of circuit model; Antenna element spacing.