Browsing by Author "Abdalla, Mahmoud A."

Now showing 1 - 3 of 3

Compact and wideband microwave bandstop filter for wireless applications
(Springer, 2020) Ibrahim, Ahmed A.; El Shafey, Omar K.; Abdalla, Mahmoud A.
Compact, tunable and wide band stop filter (BSF) for wireless application is presented. The proposed filter is composed of compact rectangular microstrip open loop resonator with stub loaded resonator as building blocks of the filter. First, two vertical lumped capacitors are inserted in the open loop resonator from top to bottom of the substrate at the place which has maximum electric field to decrease the resonance frequency which in turn miniaturize the filter size. The resonance frequency of the fundamental mode is shifted from 5.5 to 4.2 GHz when lumped capacitors of 0.2 pF are added. Second, the capacitance of the open-ended stub can be changed to control the second resonance mode of the filter. Also, by inserting another vertical capacitor at the end of the open-ended stub, the second resonance mode can be controlled and reduced. Finally, by properly selecting the capacitance of the third lumped capacitor, the second resonance mode can be designed to be close to the fundamental mode and hence wide band stop filter can be achieved. The proposed BSF has some appropriate features such as compact size (its size has more than 40% size reduction), wide stopband and most importantly tunability of stopband. The band stop filter has a center frequency of 6.2 GHz, a stop band from 3.5 to 9 GHz, insertion loss lower than − 30 dB, and a return loss higher than 0.4 dB is accomplished inside the stop band. The measured results have good matching with the simulated results. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
Concept and analysis of a coupled split-ring resonator for wide-/dual bands, self-filtering, high out-of-band suppression and highly efficient antennas
(Cambridge University Press, 05/12/2020) Abdalla, Mahmoud A.; El Atrash, Mohamed; El-Sobky, Nour A.; Zahran, Sherif R.
An inspired metamaterial-based highly efficient monopole antenna displaying wide-/dual-band resonances along with self-filtering properties is presented. The monopole has high out-of-band suppression characteristics that lead to very close to 0 dB band-stop between the antenna dual resonant bands. The antenna operates at the two WLAN services of 2.65-3.25 and 5-7 GHz with stopband with total reflection at 4.5 GHz. The designed filtering characteristics are based on current coupling for the dual-band functions and current neutralization for the stopband function. Moreover, the proposed antenna has a very high radiation efficiency of 97 and 99% at 3 and 6 GHz, respectively. Furthermore, the proposed antenna exhibits an omni-directional radiation pattern with coplanar waveguide feed for simple integration with passive/active devices. Moreover, the antenna properties are achieved with a compact antenna size (30 × 30 mm2). With all presented results, the proposed antenna is very competitive over recent relevant antennas. In addition, a very good agreement between theoretical, full-wave simulations and measurements is achieved. © 2020 Cambridge University Press and the European Microwave Association
A Wearable Dual-Band Low Profile High Gain Low SAR Antenna AMC-Backed for WBAN Applications
(IEEE, 2019-10) Abdalla, Mahmoud A.; El Atrash, Mohamed; Elhennawy, Hadia M
A dual-band, low profile, high gain, and low specific absorption rate (SAR) triangular slotted monopole antenna backed with a artificial magnetic conductor (AMC) array is presented for wireless body area network (WBAN) applications. The antenna is printed on a Rogers ULTRALAM 3850 substrate, whereas the AMC array is printed on a RO3003 substrate. The design operates at 3.5 GHz, for WiMAX wireless applications, and at 5.8 GHz for the ISM Band. The proposed antenna preserved the dual-band resonance and exhibited acceptable gain and SAR at a separation of 15 mm from the human body model. To reduce such separation and achieve enhancements to gain and SAR, an AMC array was utilized. In free space, gain enhancements by 6.8 and 3.7 dBi were achieved at both frequencies, respectively. Furthermore, over a gap of 1 mm from the human body, gain enhancements by 23.3 and 13.9 dBi …