Hadi Aliakbarian

Mutual Coupling Reduction Between Planar Antennas by Using a Simple Microstrip U-Section

Mutual coupling is an inevitable phenomenon in multiantenna systems, usually reducing the system performance. Numerous works have focused on the reduction of this effect. The aim is maintaining the mutual coupling suppressing structure as simple as possible while having a high amount of mutual coupling reduction. This letter presents a novel structure suppressing the mutual coupling between nearby patches. It is composed of only a simple U-shaped microstrip, which reduces the mutual coupling considerably. The structure has been constructed and tested. The measurement results prove the high efficiency of this configuration.

An Effective Technique for Symmetric Planar Monopole Antenna Miniaturization

The increase of mobile applications requires antennas ever smaller in form factor. In this paper, an effective method is presented for antenna size miniaturization of ultrawideband (UWB) monopole antennas with symmetric structure and perfect magnetic conductor (PMC) plane. Two small antennas are designed for pulsed UWB applications in the 3.1-10.6-GHz band with and without notch behavior in the band. The presented technique is applied to both antennas for an even further 50% area reduction. The performance of the miniaturized antennas is then compared with the main-size structures. Using both simulations and measurements the paper analyzes and demonstrates in detail the effectiveness of the presented technique in the time and frequency domain.

Novel Low-Cost End-Wall Microstrip-to-Waveguide Splitter Transition

A novel conflguration for an end-wall microstrip-to- waveguide splitter transition is presented suitable for use in series fed microstrip arrays. The low price, simplicity, manufacturability, low sensitivity, and also wideband operation, up to more than 37%, is the result of positive interaction between double slots and double stubs. The transition is applied to a dual band 1 £ 2 array. A wideband non-tilted pattern is achieved.

A Novel Electrically Small Spherical Wire Antenna With Almost Isotropic Radiation Pattern

Two new electrically small spherical antennas are presented in this letter. The antennas have perpendicular arms to reduce radiation cancellation. While having low resonant frequency and high radiation efficiency, the radiation patterns of the antennas are almost isotropic. The proposed folded spherical wire antenna (SWA) shows approximately 50-Omega radiation resistance which eliminates the need for using a matching circuit for antenna feeding. Moreover, the proposed folded SWA is fabricated to verify simulation results. An attempt has been made to approach the fundamental limitations of small antennas for better characteristics while keeping the size as small as possible.

Implementation of a Project-Based Telecommunications Engineering Design Course

This paper describes and discusses the implementation of a project-based graduate design course in telecommunications engineering. This course, which requires a combination of technical and soft skills for its completion, enables guided independent learning (GIL) and application of technical knowledge acquired from classroom learning. Its main implementation challenge is the need for instructors to define graduate-level GIL activities that are unique for the project objectives and scope. This process is required at both the system and subsystem levels. These activities must also satisfy the program learning outcomes and course outcomes (PLOs and COs). The course initiation, implementation, and management are first described from the instructors perspective. Technical specifications and outcomes from a recently implemented project titled “A Human-Inspired Telecommunication System” is taken as a case study. Besides explaining the methodology used to evaluate both the course and the students, an empirical assessment of PLOs and COs against the associated educational activities is also presented. Results of a student exit survey, in which each instrument was mapped to specific COs, indicated that the intended course objectives had been accomplished and that there was a good level of student satisfaction.

A Simple Real-Coded Compact Genetic Algorithm and its Application to Antenna Optimization

Based on Hariks compact genetic algorithm, in this paper a real-coded type of compact genetic algorithm, RCGA, based on probability distribution function of each gene is developed. The algorithm is applied to design a new small-size tapered monopole ultra-wideband antenna as a practical utilization. The antenna is a modified PTMA which is able to improve the bandwidth using eleven degrees of freedom. The final optimized antenna design works from 3.1 to 11.7 GHz and has only 48% of the size compared to previous work.

An Architectural Scheme for Real-Time Multiple Users Beam Tracking Systems

In this paper, the design, building, and functioning of a complete communication system with 16 antenna elements, software-defined radio, and beam-tracking capabilities for up to four users is reported. Since the design uses components off the shelf, it is relatively low cost, which makes it feasible to be used in high-volume commercial applications. A key feature is that all digital beamforming and advanced direction-of-arrival tracking algorithms are integrated into one segment—the multiple users beam tracker. Experimental results with regard to system performance, responding time, and efficiency illustrate the effectiveness of the concept.

Miniaturization of UWB Antennas and its Influence on Antenna-Transceiver Performance

A modified small-size tapered monopole antenna is optimized for ultra wideband applications in co-design with the transceiver. Our optimization procedure aims at finding an antenna not only with low VSWR, but also miniaturizing the antenna at the same time. Our proposed optimization algorithm, real-coded compact genetic algorithm, RCCGA, has lowered the antenna area more than 48% compared to previous work for 3.1 to 11.7 GHz bandwidth operation. Design with the need for co-design and co-integration of the whole system the optimized antenna area is even more miniaturized and this paper explains in detail the trade off between antenna size, antenna performance and transceiver performance.

A modified small-size tapered monopole antenna for UWB applications designed by genetic algorithm

In this paper, a modified small-size tapered monopole antenna is optimized for ultra wideband applications. Our optimization procedure aims at finding an antenna not only with low VSWR, but also miniaturizing the antenna at the same time. In addition, since in UWB communication pulse distortion between the receiver and the transmitter is very crucial the impulse responses of the designed antennae were considered. The optimization technique proposed here is a real-coded compact genetic algorithm, RCCGA, based on the probability density function of each variable. The final design of the antenna works from 3.1 to 11.7 GHz with 48% lower area compared to previous work.

Low-Radiation-Loss Waveguide-to-Microstrip Transition Using a Double Slit Configuration for Microstrip Array Feeding

In this paper, a waveguide-to-microstrip transition is introduced. This end-wall transition employs a double slit configuration in the ground plane of a microstrip line to couple the electromagnetic waves. The purposed transition features lower radiation losses in comparison with existing waveguide-to-microstrip transitions.