Guang Hua

A Highly Accurate FGG-FG-FFT for the Combined Field Integral Equation

In this paper, a novel realization of the Integral Equation in combination with the fast Fourier transform for the CFIE is established by Fitting both the Greens function and its Gradient onto the nodes of a uniform Cartesian grid. The new method has been compared with several existing popular FFT-based methods, including the AIM, the IE-FFT, and the p-FFT. The accuracy of the proposed method is significantly higher than other FFT-based methods, and the method is not sensitive to both the grid spacing and the expansion order. The outstanding merit of the proposed method is that the fitting procedure is independent of the basis functions. Therefore, when the higher order basis functions would be adopted in the method of moments, only one fitting procedure for the Greens function and its gradient on a basis function support is needed to meet all of basis functions defined on this support. Some numerical examples are provided in this paper to demonstrate the accuracy and efficiency of the proposed method.

Design of an omnidirectional line array with SIW longitudinal slot antenna

An omnidirectional slot array antenna based on substrate integrated waveguide (SIW) technology is developed in this letter, which inherits the merits of small size, low profile, and low cost etc. form SIW. Omnidirectional SIW slot array antennas are realized by etching longitudinal slots on both sides of the top and bottom metallic planes of a SIW. The experiment results for 6 GHz wireless access applications show that 3% bandwidth (VSWRles1.5) and a very good omnidirectional radiation pattern are achieved.

A novel FG-FFT method for the EFIE

In this paper, a novel realization of the FFT-based methods for the EFIE with high accuracy is established by fitting the Greens function onto the nodes of a uniform Cartesian grid. Like the IE-FFT, the focus of the proposed method is the Green function, but the accuracy of new method is significantly higher than that of the IE-FFT. Some numerical examples are provided to demonstrate the accuracy and efficiency of the proposed method.

Microstrip Folded Dipole Antenna for 35 GHz MMW Communication

A microstrip asymmetric folded dipole antenna on chip is proposed in this paper. The construction of balun feed line is adopted to provide wideband. A new design procedure based on the odd-even mode method to calculate the input impedance of an asymmetric strip folded dipole antenna is presented. The folded dipole antenna has the advantage of small size, low profile, low cost, and so forth. The measured results show that a miniaturized antenna has the bandwidth of more than 14.2% (VSWR 2); gain of the antenna is 5.7 dB at 35 GHz.

An accurate approach for the calculation of MoM matrix elements

The method of moments solution on integral equations for electromagnetic scattering and radiation problems with Rao-Wilton-Glisson (RWG) and n/spl times/RWG basis functions requires the calculation of singular double surface integrals over triangular subdomains. In this paper, an approach is presented to deal with the singularity and almost singularity in which the triangle subdomain is divided into several subtriangles and then the singular or almost singular integral is calculated over each of the subtriangles. This approach is mainly based on the projection process and the local polar frame. It can be used to deal with the singular double surface integrals of order 1/R and 1/R/sup 2/, in which vector functions may be of zeroth-order and higher order. Numerical examples are provided to verify the validity of the method presented in this paper for dealing with the singularity and almost singularity.

Design and Optimization of a Millimetre Wave Compact Folded Magic-T

A millimetre wave-folded magic-T junction compensated with metal cone is designed using a particle swarm optimization (PSO) algorithm. An off-centred metallic frustum was used to enhance the bandwidth and a metallic post is used to compensate the mismatched E-arm. The geometrical parameters of the frustum and the post are optimized by PSO. The optimized magic-T for W-band application is designed and tested. The design features are simple in structure and easy to fabricate. The 2% bandwidth with centre frequency of 94 GHz and return loss less than −20 dB is achieved.

The MLFMA Equipped with a Hybrid Tree Structure for the Multiscale EM Scattering

We present an efficient strategy for reducing the memory requirement for the near-field matrix in the multilevel fast multipole algorithm (MLFMA) for solving multiscale electromagnetic (EM) scattering problems. A multiscale problem can obviously lower the storage efficiency of the MLFMA for the near-field matrix. This paper focuses on overcoming this shortcoming to a certain extent. A hybrid tree structure for the MLFMA that possesses two kinds of bottom-layer boxes with different edge sizes will be built to significantly reduce the memory requirement for the near-field matrix in the multiscale case compared with the single-tree-structure technique. Several numerical examples are provided to demonstrate the efficiency of the proposed scheme in the multiscale EM scattering.

A SPST PIN switch for C-band dual-band antenna applications

In this paper, the design of a C-band PIN diode switch for dual-band antenna application is presented. The purpose of this design is to meet the requirement that the antenna can operate at two different frequencies by turning on and off it. When the PIN diode is reverse biased, the switch is off and the antenna operates at 3.6GHz. When the PIN diode is forward biased, the switch is on and the antenna operates at 2.4GHz. The measured impedance bandwidth (return loss<;-10dB) is 550 MHz (2-2.55GHz) and 1.22GHz (3.1-4.32GHz) for 2.4GHz and 3.6GHz, which is very close to the simulation results. At the mean time, the switch barely has effect on the radiation patterns of the antenna.

Efficient two dimensional direction finding via auxiliary-variable manifold separation technique for arbitrary array structure

A polynomial rooting Direction of Arrival (DOA) algorithm for multiple plane waves incident on an arbitrary array structure that combines the multipolynomial resultants and matrix computations is presented in this paper. Firstly, a new auxiliary-variable manifold separation technique (AV-MST) is proposed to modal the steering vector of arbitrary array structure as the product of a sampling matrix (dependent only on the array structure) and two Vandermonde-structured wavefield coefficient vectors (dependent on the wavefield). Then the propagator operator is calculated and used to form a system of bivariate polynomial equations. Finally, the automatically paired azimuth and elevation estimates are derived by polynomial rooting. The presented algorithm employs the concept of auxiliary-variable manifold separation technique which requires no sector by sector array interpolation and thus does not suffer from any mapping errors. In addition, the new algorithm does not need any eigenvalue decomposition of the covariance matrix and exhausted search over the two dimensional parameter space. Moreover, the algorithm gives automatically paired estimates, thus avoiding the complex pairing procedure. Therefore, the proposed algorithm shows low computational complexity and high robustness performance. Simulation results are shown to validate the effectiveness of the proposed method.

Efficient Two-Dimensional Direction Finding via Auxiliary-Variable Manifold Separation Technique for Arbitrary Array Structure

A polynomial rooting Direction of Arrival (DOA) algorithm for multiple plane waves incident on an arbitrary array structure that combines the multipolynomial resultants and matrix computations is presented in this paper. Firstly, a new auxiliary-variable manifold separation technique (AV-MST) is proposed to modal the steering vector of arbitrary array structure as the product of a sampling matrix (dependent only on the array structure) and two Vandermonde-structured wavefield coefficient vectors (dependent on the wavefield). Then the propagator operator is calculated and used to form a system of bivariate polynomial equations. Finally, the automatically paired azimuth and elevation estimates are derived by polynomial rooting. The presented algorithm employs the concept of auxiliary-variable manifold separation technique which requires no sector by sector array interpolation and thus does not suffer from any mapping errors. In addition, the new algorithm does not need any eigenvalue decomposition of the covariance matrix and exhausted search over the two dimensional parameter space. Moreover, the algorithm gives automatically paired estimates, thus avoiding the complex pairing procedure. Therefore, the proposed algorithm shows low computational complexity and high robustness performance. Simulation results are shown to validate the effectiveness of the proposed method.