Adel B. Abdel-Rahman

Control of bandstop response of Hi-Lo microstrip low-pass filter using slot in ground plane

This paper examines the effect of the geometrical shapes of a defected ground-plane structure (DGS) slot on performance of the Hi-Lo microstrip low-pass filter (LPF). A three-pole LPF based on an arrowhead DGS slot has 67% less length as compared to a conventional three-pole LPF. It has insertion loss of 0.5 dB and 15-dB rejection in the stopband up to three times the cutoff frequency.

Wideband aperture coupled microstrip antenna

Investigations with the goal of obtaining wide bandwidth of a microstrip antenna, for applications in printed antenna arrays, are described. The best simulated antenna configuration is fabricated and tested. The measured fractional impedance bandwidth is 12.4%, and the gain of the antenna ranged from 5.9 to 7.4 dB over the same frequency bandwidth. The experimental results are in good agreement with the simulation. Methods for impedance bandwidth enhancement are also discussed.

Compact stub type microstrip bandpass filter using defected ground plane

Usually a defected ground plane structure (DGS) provides only a band-reject response. However, in this work we introduce a simple band-accept circuit element in the DGS and developed a microstrip stub type compact 3-pole bandpass filter (BPF) at 4.2 GHz. The BPF has bandwidth and insertion loss 38% and 0.6 dB respectively. It has better than 25 dB rejection in the stopband up to 12 GHz.

Compact bandpass filters using defected ground structure (DGS) coupled resonators

This paper introduces new compact DGS resonators and ways to implement intra-resonator and external coupling. Different coupling configurations are considered. These new resonators are then applied to design bandpass filters with Chebyshev or pseudo-elliptic responses. Experimental results are presented to show the performance of these filters.

Game Theory Meets Wireless Sensor Networks Security Requirements and Threats Mitigation: A Survey

We present a study of using game theory for protecting wireless sensor networks (WSNs) from selfish behavior or malicious nodes. Due to scalability, low complexity and disseminated nature of WSNs, malicious attacks can be modeled effectively using game theory. In this study, we survey the different game-theoretic defense strategies for WSNs. We present a taxonomy of the game theory approaches based on the nature of the attack, whether it is caused by an external attacker or it is the result of an internal node acting selfishly or maliciously. We also present a general trust model using game theory for decision making. We, finally, identify the significant role of evolutionary games for WSNs security against intelligent attacks; then, we list several prospect applications of game theory to enhance the data trustworthiness and node cooperation in different WSNs.

Coupling Reduction of Antenna Array Elements Using Small Interdigital Capacitor Loaded Slots

Small size capacitor loaded ground plane slots are used to reduce the mutual coupling between elements in a microstrip antenna array design. The proposed compact slots are inserted between the adjacent E-plane coupled elements in the array to limit the propagation of surface waves between the elements of the array. In order to validate the feasibility of the proposed structure, a two-element array with 0.5‚o distance between centers of two patches is designed, fabricated, and measured. The measured results show a reduction in mutual coupling of 17dB obtained between elements at the operation frequency.

Small size third order coupled resonator band-pass filter using capacitor loaded slots

In this paper, we present a small size third order band pass coupled resonator filter. The filter consists of defected ground structure resonators (DGSs). The reduction of the size is achieved by loading the resonator with lumped capacitor. The insertion of lumped capacitor within resonator increases the effective capacitance and reduces the resonant frequency, so the dimensions of the filter will reduce and the performance of the filter will improve by enhancing the energy stored in the resonator. A third order band pass filter with center frequency of 2.4GHZ with single transmission zero at 2.61 GHz is designed and simulated. The filter has pass band from 2.3 to 2.52 GHz and wide stop band with rejection higher than 20dB up to more than 8GHZ, and insertion loss lower than 1 dB is achieved within pass band.

A Novel Technique for Compact Size Wireless Power Transfer Applications Using Defected Ground Structures

This paper presents a novel technique for high efficiency and compact size wireless power transfer (WPT) systems. These systems are based on coupled defected ground structure (DGS) resonators. Two types of DGSs (H-shape and semi-H-shape) are proposed. The semi-H-shaped DGS realizes larger inductance value, and this results in higherWPT efficiency. Instead of using an inductive-fed resonant coupling, we propose capacitive-fed resonant coupling, which reduces the design complexity and enhances the efficiency further. The DGS resonator of both the systems is loaded by chip capacitors for miniaturization. An equivalent circuit using approximate quasi-static modeling is extracted. An analytical design procedure is developed to calculate the optimum design parameters for the proposed WPT systems. The optimized structures are fabricated and measured. The simulation and measurement results are in good agreement. The proposed semi-H-shaped DGS WPT system has a peak efficiency of 73% at a transmission distance of 25 mm. In turn, the figure of merit becomes the highest among the WPT systems proposed so far.

Direct and cross-coupled resonator filters using defected ground structure (DGS) resonators

This paper introduces DGS resonators to be used as building blocks of coupled resonator filters. Different coupling configurations are considered. These new resonators are then applied to design a multilayer second-order coupled resonator bandpass Chebychev filter and a fourth order cross-coupled resonator pseudo-elliptic filter. Experimental results are presented to show the performance of these filters.

Strong resonant coupling for short-range wireless power transfer applications using defected ground structures

This paper presents a new structure for highly efficient short-range wireless power transfer. The proposed structure is based on strongly coupled resonators using H-slot defected ground structures. An equivalent circuit model for H-slot coupled resonators is introduced. Measurement results for the new proposed structure show a power transfer efficiency of 70% at 15 mm distance between driver and load resonators. Experimental measurements have shown good agreement with electromagnetic and circuit simulations.