A single layer, single feed compact rectangular microstrip antenna is proposed. Resonant frequency has been reduced drastically by cutting unequal rectangular slots at the edge of the patch. Two rectangular slots are introduced at the left and right side of the patch to reduce the resonant frequency. The widths of the rectangular slots are different to improve the gain bandwidth performance of the antenna. The antenna size has been reduced by 73.9% when compared to a conventional rectangular microstrip patch antenna. The characteristics of the designed structure are investigated by using Method of Moment‐based electromagnetic solver, IE3D. There is a reasonable agreement between these simulated data and measured values. An extensive analysis of the return loss, radiation pattern, gain, and efficiency of the proposed antenna is shown in this paper. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication and make it suitable for the applications in Wireless communication system. Mainly, it is developed to operate in the mobile communication range of 900 MHz–1.8 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:954–957, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27517
In this article, band pass cylindrical double‐layer frequency selective surfaces (FSSs) are investigated using method of moment (MOM). “Plus”‐shaped slots are used to design the FSSs. The dielectric substrate is considered as air. A good bandwith and sharp roll off are achieved for curved FSS. Theoretical and measured investigations have been done by FEKO simulator and microwave test bench setup, respectively.
Simulated and experimental investigations on hexagonal ring based aperture and patch type semi cylindrical curved frequency selective surfaces (FSSs) have been presented. Simulated and experimental results are in good agreement. Also, the parametric studies have been done for patch and aperture type Curved FSSs. Curved FSS structures are recently being investigated to design radome or nose of fighter aeroplane. This study will help the researchers to design curved frequency selective structures with both band pass and band stop properties.aperture and patch type, curved frequency selective surface, measurement, multilevel fast multipole method (MLFMM), parametric studies Abstract A missile-borne conformal array antenna with off-axis radiation is designed in this article. 16 inclined radiation elements are connected by a power divider to form a conformal array, which consists of an active patch and a parasitic patch with an open-circuit stub. By coplanar coupled feeding and adjusting the length of the open-circuit stub, the radiation pattern toward axis-direction of missile is realized. Experimental results show the antenna can cover 5.25-5.45 GHz with 210 dB return loss and with off-axis radiation. Due to its excellent electrical performance and conformal ability, it can be widely used on the missiles. K E Y W O R D S conformal array antenna, missile-borne antenna, off-axis radiation
A simple generalized theory is presented for the determination of interband optical absorption coefficient (IOAC) around band edges, in quantum well (QW) structure of non-parabolic semiconducting materials whose band structures obey the three band model of Kane. The dependence of absorption coefficient on wave-vector (k→) has also been investigated. IOAC has been calculated for a wide range of III–V compound semiconductors, such as InAs, InSb, Hg1−xCdxTe, and In1−xGaxAsyP1−y lattice matched to InP. It has been found that IOAC for QWs increases in steps with increasing photon energy and the positions of jumps of the coefficient are more closely spaced in the three band model of Kane than those with parabolic energy band approximations in all the cases. IOAC for QWs is largely dependent on the polarization direction of the incident light and on the well dimension as well. The expressions of IOAC presented in this article can easily be extended to incorporate the effects of different external conditions like strain, electric, and magnetic fields on IOAC. It has also been shown that under certain limiting conditions the expressions for IOAC reduces to the previously known results for wide band gap materials and this is the indication for it to be a generalized theory for IOAC.
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