Browsing by Author "Sree, Mohamed Fathy Abo"

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Citation - WoS: 6
Citation - Scopus: 7
A Novel Circular Reconfigurable Metasurface-Based Compact Uwb Hybrid Coupler for Ku-Band Applications
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Abbas, Mohamed Atef; Cengiz, Mehmet Faruk; Allam, A. M. M. A.; Fawzy, Diaa E.; Elhennawy, Hadia M. M.; Sree, Mohamed Fathy Abo
A novel circular reconfigurable metasurface (MS) based compact ultra-wideband (UWB) hybrid coupler is developed for Ku-band applications. The coupler is developed using the substrate-integrated gap waveguide (SIGW) technology. The coupler structure consists of two layers, the bottom layer represents the artificial magnetic surface of the periodic structures and the ridges in between that guide the wave in the required direction with minimum dispersion. It involves the coupling section with a centered etched slot and two additional vias to achieve the basic hybrid coupler properties. This layer is nominated as the ridge layer. The second layer is a circular shape of a dielectric gap loaded with the top ground. The top ground is left solid for a non-reconfigurable coupler. Concerning the reconfigurable coupler, this layer contains an artificial metasurface of Jerusalem cross elements where the copper is etched around. This layer is nominated as the gap layer. This MS surface is mechanically rotated to offset the magnitude and phase of the signal going to the through and coupled ports. The findings obtained from the simulations show that the reconfiguration can be accomplished by rotating the MS around the source coupler's central axis. The rotation is tested between 0 & DEG; to 180 & DEG; in the counter-clockwise direction. The operating frequency range of the coupler is between 11.94 to 16.91 GHz, which covers approximately the whole Ku-band. The coupler delivers continuously adjustable amplitude between 2.6 and 4.8 dB while the phase differences within 77 & DEG; to 105 & DEG; over a fractional bandwidth (FBW) of 34.45%. It is manufactured using PCB technology and measured using network analyzer. A strong agreement is achieved between simulations and measurements. The proposed coupler can be used in traditional beam-forming and beam-steering networks by changing the rotation angle or the operating frequency. The developed coupler can replace the Butler and Bless matrices with their complication, heavy number of phase shifters, and crossover problems. The current work can be extended to operate in the mm-Wave band by changing the dimension and the material of the unit cell of the ridge layer of the coupler.
Citation - WoS: 5
Citation - Scopus: 12
Ridge Gap Waveguide Wideband Hybrid Directional Coupler for Ka-Band Applications
(IEEE, 2020) Soliman, Mohamed Yasser; Ali, Mohamed Mamdouh M.; Shams, Shoukry, I; Sree, Mohamed Fathy Abo; Fawzy, Diaa E.; Allam, A. M. M. A.
The fifth generation (5G) is the next wireless mobile communication technology that targets to provide huge capacity, low latency and high data speeds. Like any new wireless technology, 5G requires the development of exciting techniques, where access to high frequency spectrum can achieve the desired characteristics. In addition, new systems must be developed and designed using wide bandwidth microwave components, which should be implemented with modern and efficient guiding structures. Among all the microwave components, directional coupler is essential device as it can be used to realize many subsystems such as beamforming networks. In order to keep up with the huge changes in future technologies, couplers still requires noticeable improvement, where wide bandwidth and low loss should be achieved throughout using modern guiding technology such as Ridge Gap Waveguide (RGW). In this paper, a design of ultra-wideband 3 dB quadrature hybrid directional coupler using RGW technology is introduced. The proposed coupler has a compact size of 1.58 lambda x 1.4 lambda and achieves a relative bandwidth of 44.7 % at 33.5 GHz, which cover the whole ka-band. In addition, a stable 90 degrees phase difference between the coupling and transmission coefficients is obtained over the whole frequency band.