Rashid Mirzavand

Compact Microstrip Wilkinson Power Dividers With Harmonic Suppression and Arbitrary Power Division Ratios

This paper describes a new Wilkinson power divider on a single-layer microstrip line that can reduce the occupied area, suppress the harmonic components, and/or provide the arbitrary power division ratios. It consists of two-section transmission lines, two inductors, and one isolation resistor. Four different designs have been conducted to investigate the capabilities of the structure. In addition, a compact divider along with harmonic suppression and a practical divider with a large power-dividing ratio has been constructed and measured. The simulation and measurement results are in good agreement with each other. This indicates that the structure can effectively be used as a power divider for miniaturized or arbitrary power division ratio applications.

Five-port microwave receiver architectures and applications

Five-port architectures are investigated as direct conversion receivers for radio communications. Moreover, the five-port applications in different wireless and radio systems are explained. Using simulation and measurement studies, it is shown that the five-port architecture can be used as a low-cost, compact-size, and high-performance receiver in different radio systems.

Full-Wave Semiconductor Devices Simulation Using Adi-FDTD Method

This paper describes the alternating-direction implicit flnite-difierence time-domain (ADI-FDTD) method for physical modeling of high-frequency semiconductor devices. The model contains the semiconductor equations in conjunction with the Maxwells equations which describe the complete behavior of high- frequency active devices. Using ADI approach leads to a signiflcant reduction of the full-wave simulation time. We can reach over 99% reduction in the simulation time by using this technique while still have a good degree of accuracy compared to the conventional approaches. As the flrst step in the performance investigation, we use the electrons ∞ow equations in the absence of holes and recombination as semiconductor equations in this paper.

Metamaterial-Based Phase Shifters for Ultra Wide-Band Applications

In this paper, the idea of using two composite right/left handed (CRLH) transmission lines (TLs) in design of microstrip phase shifter is suggested for the first time and optimized by Genetic Algorithm for achieving the desired magnitude and phase characteristics over ultra wide-band range of microwave frequencies. In this paper, a 90° phase shifter is developed in an extra wide bandwidth from 3 GHz to 10 GHz, with only ±5° phase error. The proposed phase shifter is useful for UWB applications which can be implemented by both the lumped-elements and microstrip CRLH TLs.

Closed-Form Design of Gysel Power Divider With Only One Isolation Resistor

An innovative design of low profile in-phase Gysel power divider (PD) by introducing efficient modifications is presented. The conventional Gysel uses a half-wave line and two isolation resistors as a Π network. The proposed modification converts it to a T network with only one isolation resistor and two quarter-wave lines that can reduce the design complexity, occupied area and fabrication cost. To obtain the accurate values of the line impedance and isolation resistance, closed-form equations based on a new viewpoint are derived. Two prototypes with narrow and broadband characteristics are realized at 3 GHz. The PDs have good magnitude and phase balances and better harmonic performance, compared to the conventional one.

CFS-PML Implementation for the Unconditionally Stable FDLTD Method

This paper introduces the implementation of complex frequency shifted perfectly matched layer (CFS-PML) absorbing boundary conditions for the unconditionally stable finite-difference Laguerre time-domain (FDLTD) method. It has been shown that the relative performance of the CFS-PML implementations is superior to the PML and Mur ABCs performance by an example.

Direct conversion EHM transceivers design for millimeter-wave wireless applications

A direct conversion modulator-demodulator with even harmonic mixers for fixed wireless applications is presented. The circuits consist of even harmonic mixers (EHMs) realized with antiparallel diode pairs (APDPs). A communication link is set up to examine the overall performance of proposed modulator-demodulator. The transmission of 16-QAM signal with 110Mbps data rate over fixed wireless link has been examined. We also evaluate the different levels of I/Q imbalances and DC offsets and use signal space concepts to analyze the bit error rate (BER) of the proposed transceiver using-ary QAM schemes. The results show that this structure can be efficiently used for fixed wireless applications in Ka band.

Five-port receiver implementation in Ka-band for software-defined radio

A five-port Ka-band direct conversion receiver based on Six-port structures has been presented that is very suitable for software defined radio applications. An experimental prototype has been fabricated using microstrip components for 23-29 GHz frequency band. Simulation and measurement results are presented to validate the proposed approach. An exellent agreement shows the accuracy of the proposed technique.

Unconditionally Stable MFLTD Method for the Full Wave Electromagnetic Simulation

A new unconditionally stable numerical method for the time domain simulation of electromagnetic problems using a combination of the Laguerre polynomials in the time domain and radial basis functions (RBF) in the spatial domain named mesh-Free Laguerre time domain (MFLTD) method is described. Unconditionally stable Laguerre based method may be computationally much more efficient than the FDTD methods and using RBFs allows computing the problems with complex-shapes in a non-uniform points distribution. A numerical example at the final part of the communication shows the efficiency of the presented method in problems with sparse and coarse regions. Using the MFLTD method for this example, we can achieve a 96% reduction in the computation time and get an acceptable degree of accuracy in comparison to the conventional mesh-free time-domain (MFTD) method.

LOD-FDTD method for physical simulation of semiconductor devices

This paper describes a locally one-dimensional finite-difference time domain method for the two-dimensional time-dependent simulation of semiconductor devices. This approach leads to significant reduction of the semiconductor simulation time. We can reach over 80% reduction in the simulation time by using this technique while maintaining the same degree of accuracy achieved using the conventional approach. As the first step in the performance investigation, we use the electrons flow equations in the absence of holes and recombination in this paper.