Muhammad Asad Rahman

Design and parametric analysis of a planar array antenna for circular polarization

A new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications. Four square patch elements with feed network are used to design the circularly polarized array antenna. The feed network consists of microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. Both-sided MIC technology is successfully employed to apply its inherent advantages in the design process of the array structure. The unequal feed line is used to create 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Characteristics of the proposed array are investigated by using two electromagnetic (EM) simulators: advanced design system and EMPro. The −10 dB impedance bandwidth of the antenna is around 5%. The 3 dB axial ratio bandwidth of 1.48% is obtained. The design of the proposed antenna along with parametric study is presented and discussed.

Design of a circular polarization array antenna with dual-orthogonal feed circuit

In this paper, the design of a circularly polarized array antenna at 10 GHz frequency is presented. The proposed antenna consists of a 1×2 array antenna with feed circuit. To realize circular polarization, dual-orthogonal feed circuit is used that excites two orthogonal modes with equal amplitude but quadrature in phase. Feed circuit is designed using microstrip lines and slot lines where microstrip lines are placed on the top surface of the substrate and slot lines on the reverse side of the substrate. The feed point is chosen in such a way that it provides the each patch element two RF signals with 90° phase difference. Therefore, the circular polarization is realized by employing microstrip-slot feed circuit. “Both-Sided MIC Technology” is used to design the proposed array antenna as it gives flexibility in the design process. The simulated return loss of the proposed array antenna is less than -45 dB at the design frequency. The 3 dB axial ratio bandwidth of 0.8% is obtained. The structure and the basic behavior along with the simulation results of the proposed circularly polarized array antenna are demonstrated in this paper.

Design of a dual circular polarization microstrip patch array antenna

Design of a microstrip array antenna to achieve dual circular polarization is proposed in this paper. The proposed antenna is a 2×2 array antenna where each patch element is circularly polarized. The feed network has microstrip lines, cross slot lines and air-bridges. The array antenna can excite both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) without using any 90° hybrid circuit or PIN diode. “Both-sided MIC Technology” is used to design the feed network as it provides flexibility to place several types of transmission lines on both sides of the dielectric substrate. The design frequency of the proposed array antenna is 10 GHz. The simulated return loss exhibits an impedance bandwidth of greater than 5% and the 3-dB axial ratio bandwidths for both RHCP and LHCP are approximately 1.39%. The structure and the basic operation along with the simulation results of the proposed dual circularly polarized array antenna are demonstrated in this paper.

Design of a circular polarization array antenna using linear polarization patches

This paper presents a new circularly polarized array antenna using linearly polarized microstrip patches with a gain of 7.47 dBi. The array structure consists of four square patch antennas with feed network. The feed network is designed using microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. The Teflon glass fiber substrate is used with a permittivity of 2.15. The design frequency of the proposed array antenna is 10 GHz where simulated return loss is less than -45dB. The unequal feed line is used in order to realize 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Advanced Design Systems (ADS) by Agilent Technologies is used for the simulation of the proposed array antenna.

Design of an x-band microstrip array antenna for circular polarization

In this paper, the design of a circularly polarized array antenna with 9.56 dBi of gain at 10 GHz frequency is presented. The proposed antenna consists of a 2×2 array antenna with feed network where all microstrip patches are linearly polarized. “Both-Sided MIC Technology” is used to design the proposed array antenna. The simulated return loss of the proposed array antenna is less than -35dB. The 3 dB axial ratio bandwidth of 2.21% is obtained. The unequal feed line is used in order to realize 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. The structure and the basic behavior along with the simulation results of the proposed linearly polarized array antenna are demonstrated in this paper.

Numerical analysis of deep level defects in Cu 2 ZnSnS 4 (CZTS) thin film solar cells

Cu₂ZnSnS₄ (CZTS) absorber layer has recently been put under extensive research as a potential replacement of CIGS absorber layer because of its excellent electrical and optical properties. In this work, CdS, ZnS, ZnSe, In₂S₃ and TiO₂ have been used as buffer layers in a CZTS/Buffer/i-ZnO structure. The use of i-ZnO as a Transparent Conducting Oxide (TCO) layer has been seen to enhance the performance of an ideal CZTS absorber layer without deep level defects. The effects of deep level defects on the performance of the cells have been numerically analyzed in terms of the energetic distribution and capture cross-section parameters. CZTS/In₂S₃/i-ZnO structure showed the best efficiency of 11.68% (with V_OC = 0.77V, J_SC = 26.66 mA/cm² and Fill Factor = 56.96%). A variation of impurity concentrations have been used to offset the deterioration of efficiency and an optimum acceptor concentration of 2×1016 cm^-3 was found for the enhancement of lower performance caused by electron and hole capture cross section parameters. The efficiency of the CZTS/In₂S₃/i-ZnO structure improved up to 14.56%. Furthermore, layer thickness has also been investigated as a potential way of compensating the effects of deep level defects. Finally, temperature dependence of various structures has been observed.