Said Abushamleh

Printed Yagi-Uda array for MIMO systems

In this paper, A Yagi-Uda antenna array consisting of four radiating elements is presented. The array elements are oriented back to back in a cross fashion to achieve a pattern orthogonality utilizing the end-fire radiation characteristics of the Yagi-Uda antennas. This technique is proposed to reduce the mutual coupling between the radiating elements which is essential to the performance of Multiple Input Multiple Output (MIMO) systems. Design and simulations are conducted using CST Microwave Studio which is based on the Finite Integration Technique (FIT). Results show that the correlation level is below -35 dB between the array elements at 5.2 GHz with about λ/4 separation distance.

Mutual coupling reduction between two patch antennas using a new miniaturized soft surface structure

Two patch antenna elements are designed to work at 5.8 GHz frequency. The E-plane mutual coupling between the two antenna elements has been reduced by 10 dB by using a new miniaturized soft surface structure that allows a λ0/2 distance between the patches. The radiation patterns show no significant change in the radiation characteristics, but better directivity, which is expected.

Enhancement of the strips electromagnetic soft surfaces using ledge edges

A new design of soft surfaces is introduced which includes ledges on both sides of the strips. The proposed design revealed a wider bandgap with a lower stopband frequency allowing for miniaturization techniques. A comparative study is conducted against the same structure without the metallic ledges.

Flexible CPW-IFA antenna array with reduced mutual coupling

In this paper, a flexible and extremely low profile CPW fed Inverted F Antenna (IFA) array is presented. The array consists of two radiating elements which are separated by λ/125 yet exhibit a low mutual coupling (-27dB). This is achieved by creating pattern diversity through defecting the ground plane and adding a parasitic structure. This technique is proposed to reduce the mutual coupling between the array elements which is essential to the performance of Multiple Input Multiple Output (MIMO) systems. Design and simulations are carried out using CST Microwave Studio which is based on the Finite Integration Technique (FIT). Results show that the proposed design is a reasonable candidate for flexible and wearable wireless systems.

Miniaturized Thin Soft Surface Structure Using Metallic Strips with Ledge Edges for Antenna Applications

A new thin electromagnetic soft surface of strips in which ledge edges are used to reduce the strip period width and in turns a miniaturized structure is achieved. The surface is tested to reduce the mutual coupling between microstrip patches separated by a half wavelength in free space (center-to- center). A 20% relative bandgap bandwidth is achieved. The measurements revealed good agreement with the simulated results.

Realization of Multi-Band 3-dB Branch-Line Couplers Using Fourier-Based Transmission Line Profiles

A new procedure for the design of multi-band branch-line couplers utilizing microstrip non-uniform transmission lines with Fourier-based profiles is presented in this article. The general method is accomplished by replacing the quarter-wave uniform transmission lines of a conventional coupler with multi-band non-uniform transmission lines of the same lengths, without including additional transmission lines or matching networks. The design of non-uniform transmission line couplers is performed using even- and odd-mode analysis. The proposed structure is relatively simple and is fabricated on a single-layered microstrip board. Two design examples of dual- and triple-band branch-line couplers suitable for global system mobile (GSM), wireless local area networks, and WiFi communications are designed, fabricated, and experimentally evaluated to validate the proposed methodology.

Flexible Yagi-Uda antenna for wearable electronic devices

Mechanical flexibility along with size, weight and cost are among the main challenges for future wearable electronic devices. In this paper, the effects of bending on a planar flexible Yagi-Uda antenna operating at WLAN (IEEE 802.11) 5.2 GHz are reported. The flat antenna achieves a relative bandwidth of 13% over which S11 is less than -10 dB, a realized gain of 8.1 dB, a front-to-back-ratio of 17 dB and a half-power beam width (HPBW) of 89°. The results showed that the antenna maintained the WLAN (5150-5350 MHz) matching bandwidth required under a wide range of bending angles ΨB.

Isolation enhancment of two planar monopole antennas for MIMO wireless applications

This paper presents a planar slotted meander line structure to reduce the mutual coupling between two microstrip fed planar monopole patch antennas. The array provides a relative operating bandwidth of 98 % (1.37-4.00) GHz matched at a reflection coefficient S11 and S22 less than -10 dB with a total realized gain of 3.9, 4.66, and 4 dB at 1.85, 2.4, and 3.5 GHz respectively. The isolation level has been reduced to less than -20 dB for a wide frequency band of 85 % (1.46-3.64) GHz. The design represents a good candidate for modern wireless standards utilizing MIMO techniques including 3GPP LTE, WiMAX, WiFi, as well as systems utilizing ISM spectrum equipped with multiple antennas.

Flexible CPW-IFA antenna for wearable electronic devices

The capability of bending, twisting and folding offered by mechanically flexible films and/or substrates along with size, weight and cost constraints are among the main challenges in future wearable electronic devices. In this paper, the effects of bending on a planar flexible CPW- IFA antenna operating at WLAN (IEEE 802.11) 2.4/5.2/5.8 GHz bandwidths is proposed. The flat antenna achieves a relative bandwidth of 14% (2.25-2.61) GHz and 42% (4.98-7.64) GHz over which S11 is less than -10 dB, and a realized gain of 1.86, 4.21 and 2.94 dB at 2.4, 5.2, and 5.8, respectively. The results show that the antenna maintained the WLAN matching lower and upper bandwidths required under a wide range of bending angles ψB.

Non-uniform PCB traces with prescribed frequency bands for improved crosstalk immunity

In this work, a new design approach for realizing printed circuit board (PCB) trace configuration with continuous impedance perturbation to reduce crosstalk in PCB interconnects is investigated. The purpose is to reduce far-end crosstalk without incorporating additional PCB components in order to modify the reactive couplings between the adjacent traces, however at the expense of the available frequency band. This is achieved by replacing a uniform victim trace on a PCB with a continuously varying-impedance trace that exhibits a lowpass filter frequency characteristic. A simplified design approach of the proposed trace impedance profile which is governed by a truncated fourier series is presented. The proposed trace shows better crosstalk reduction results compared to conventional intervening guard trace schemes. Several configurations were designed, implemented, and tested to demonstrate the advantages of the underlying principle.