Shu-Lin Chen

Determining the First-Null Mainlobe Region of an Arbitrary Pattern for 2-D Numerical Pattern Synthesis Algorithm

Determining the mainlobe region of an arbitrary pattern is a critical problem in the two-dimensional numerical pattern synthesis (2-D-NPS) method in which a number of artificial interferences with appropriate powers are distributed outside of the mainlobe region. In this communication, a novel mainlobe region determination procedure based on the seeded region growing (SRG) method is proposed. Two different stopping criterions are introduced. Several numerical synthesis examples for uniformly and nonuniformly spaced planar arrays as well as a cylindrical array with directive elements, are presented to validate the effectiveness of the 2-D-NPS with the proposed mainlobe determination procedure. The two stopping criterions are also compared with these examples.

Cavity-Backed Proximity-Coupled Reconfigurable Microstrip Antenna With Agile Polarizations and Steerable Beams

A major challenge for a combined reconfigurable antenna is to realize both polarization switching and beam steering independently in a compact antenna structure. A cavity-backed proximity-coupled reconfigurable microstrip antenna proposed in this communication provides an efficient solution. Beam lead p-i-n diodes DSM8100–000 are employed as switching elements to achieve reconfiguration. Three different linear polarizations (0°, 45°, and 90°) are realized by switching the diodes on a proximity-coupled feed network. For each polarization state, the main beam can be steered to three directions by using a reconfigurable parasitic-element network. The parasitic-element network is printed on the same plane of the radiating patch, thereby making the antenna compact. This antenna has nine different working modes, and for all the working modes, the reflection coefficients are below −10 dB with the measured realized gains ranging from 7.2 to 8.1 dBi.

Generalized 2-D Numerical Pattern Synthesis Algorithm for Low Cross Polarization and Low Sidelobe Synthesis

Numerical pattern synthesis (NPS) algorithm based on adaptive array theory is an effective spatial power pattern synthesis method for antenna arrays. In this letter, instead of using the artificial interferences weighted on the total power pattern in the conventional NPS algorithm, a generalized two-dimensional (2-D) NPS algorithm is proposed in which two weighting functions are assigned to control the copolarization and cross-polarization patterns, respectively. The weighting functions are iteratively updated until both the sidelobe and cross-polarization levels reach their prescribed ones. Two numerical examples for synthesizing the patterns of a linearly polarized planar array and a circularly polarized cylindrical array are provided to validate effectiveness and advantages of the proposed generalized 2-D NPS algorithm.

Antenna selection in the synthesis of mutlple-pattern linear arrays by iterative linear programming

The problem of selecting antennas for synthesizing multiple-pattern linear arrays is considered. It is shown that this problem can be solved by an iterative linear programming procedure. Only few iterations are required for this procedure to reach the convergence. The synthesis results show that the proposed method can select the optimum element positions and consequently reduces the number of elements, while the synthesized multiple patterns can meet the specified multiple pattern bounds.

Recent Advances in Reconfigurable Antennas at University of Technology Sydney

This paper presents an overview of the recent advances in reconfigurable antennas for wireless communications at University of Technology Sydney. In particular, it reports our latest progress in this research field, including a multi-linear polarization reconfigurable antenna, a pattern reconfigurable antenna with multiple switchable beams, and a combined pattern and polarization reconfigurable antenna.

Advances in Reconfigurable Antenna Systems Facilitated by Innovative Technologies

Future fifth generation (5G) wireless platforms will require reconfigurable antenna systems to meet their performance requirements in compact, light-weight, and cost-effective packages. Recent advances in reconfigurable radiating and receiving structures have been enabled by a variety of innovative technology solutions. Examples of reconfigurable partially reflective surface antennas, reconfigurable filtennas, reconfigurable Huygens dipole antennas, and reconfigurable feeding network-enabled antennas are presented and discussed. They represent novel classes of frequency, pattern, polarization, and beam-direction reconfigurable systems realized by the innovative combinations of radiating structures and circuit components.

Array pattern synthesis using numerical pattern synthesis algorithm including mutual coupling

In this paper, numerical pattern synthesis (NPS) algorithm integrated with seeded region growing (SRG) method is proposed to synthesize the array in the presence of mutual coupling. In order to obtain the mutual coupling between the array elements, active pattern technique is used to find active element patterns. A 4 × 8 microstrip antenna array is employed to validate the effectiveness of the proposed algorithm including mutual coupling.

Multi-linear polarization reconfigurable center-fed circular patch antenna with shorting posts

In this paper, a novel multi-linear polarization reconfigurable antenna with shorting posts, which can achieve four linear polarizations (0°, 45°, 90°, 135°), has been proposed. By switching the diodes between two groups of shorting posts, four linear polarizations can be realized. The dimensions of the proposed antenna are about 0.56λ× 0.56λ× 0.07λ at 2.4 GHz. The measured results agree well with the simulated ones.

Synthesis of Unequally Spaced Linear Antenna Arrays With Minimum Element Spacing Constraint by Alternating Convex Optimization

A novel method called alternating convex optimization is presented to synthesize unequally spaced linear arrays with minimum element spacing constraint. In this method, the problem of synthesizing an unequally spaced array is formulated as a sequence of alternating convex optimization problems, and the excitation vector and auxiliary weighting vector are alternately chosen as the optimization variables. The minimum spacing constraint for considering the physical element antenna size can be easily imposed in this alternating optimization process. Two examples for synthesizing unequally spaced linear arrays with focused and shaped patterns are provided to validate the effectiveness and advantages of the proposed method.

Generalization of matrix pencil methods to the synthesis of wideband aperiodic linear arrays with frequency-invariant patterns

The problem of generalizing the matrix pencil methods (MPM) to the synthesis of wideband aperiodic arrays with frequency-invariant (FI) patterns is considered. A new pattern sampling strategy is presented to obtain the multiple pattern data of different frequencies having the common poles. The generalized MPM (GMPM) and its forward-backward version (GFBMPM) are developed to find the best common element positions for different frequencies, which can significantly reduce the number of elements required for the desired pattern shape. Numerical examples are presented to validate the effectiveness and advantages of the proposed methods.