High Gain Dual-Polarized Meta-surface Antenna Gupta, Gaurangi; Harish, A. R.; Chivukula, Rajesh
2022 IEEE Wireless Antenna and Microwave Symposium (WAMS),
2022-June-5
Conference Proceeding
A Ku band dual linearly polarized low-profile meta-surface (MTS) radiator antenna has been proposed in this work. The patch is excited using an aperture coupled feed through the slots in a substrate ...integrated waveguide (SIW). For each polarization, the SIW cavity operates in the second order mode and the antenna is fed using two parallel slots placed close to the maximum E-field in SIW, resulting in a high gain better than 10.3 dBi. The antenna presents 16.9 % impedance bandwidth over a frequency band of 13.5 GHz to 16 GHz, corresponding to \vert \mathrm{S}_{11}\vert < -10\ \text{dB} . The antenna is fed differentially using 180° hybrid coupler leading to cross polar levels lower than 25 dB and a port-to-port isolation better than 40 dB between the two polarization ports.
The significance of compact, miniaturized antennas in modern wireless communication lies in their efficient use of space, adaptability, and versatility. Coupled microstrips are known for ...miniaturising the electrical dimensions of a patch antenna by introducing capacitive loading. This in turn increases the propagation constant and enhances slow-wave characteristics, thereby reducing the electrical dimensions of the antenna. In this work, a dual coupled slot based miniaturised antenna operating at near half-mode resonance is proposed. The electrical dimensions of the structure were reduced to 0.15\times 0.15 \lambda_{0}^{2}, but with a very low bandwidth (1.8%). To improve the bandwidth of the antenna without significantly sacrificing it electrical dimensions, slots were etched out from the ground plane of the antenna. This adds some reactance in the surface current path, which reduces the Q-factor and increases bandwidth. The increase in electrical dimensions of the antenna is found to be within tolerable limits. The proposed work is compared with prior existing literature and is found to have a larger figure of merit in terms of electrical dimensions, bandwidth and gain.
With the advancement in wireless communication technology towards 5G and higher generations, researchers have invested much efforts towards attaining high bandwidth communication. Bandwidth of a ...circular patch antenna and its overall performance has been enhanced using a novel reflective technique proposed in this paper. By exciting the patch antenna reflectively through a metallic post connected to an ungrounded coplanar waveguide (CPW) line terminated with a pair of vias attached to the line by a metallic pad, another resonance is generated near the fundamental mode, significantly improving impedance bandwidth. The bandwidth of the proposed radiator is enhanced by 387.7% when compared with that of a probefed circular patch antenna (from 6.61% to 30.11%) using the proposed technique. A radiation efficiency >90% was attained for the antenna structure mentioned in this work. The progress of the proposed design from a conventional circular patch to that of a bandwidth enhanced patch is also discussed.
Automatic detection of common carotid artery is a precursor to the computer-aided analysis of atherosclerosis. In this paper, we present an approach for common carotid artery detection based on ...normalized matched filtering technique. The algorithm performance is optimized by introducing vector inner products and norms instead of conventional mean and variance computations. The difficulties of matched filtering are overcome by normalizing the image and template vectors to unit length, yielding a cosine similarity metric. We report common carotid artery detection results on Brno University of Technology, Signal Processing laboratory (SP lab) carotid artery database amounting to a total of 971 transverse mode ultrasound images out of which 538 and 433 images are taken from Ultrasonics and Toshiba ultrasound imaging devices, respectively. The proposed method results in a common carotid artery detection accuracy of 97.63% with a detection time per image of 2.21 seconds. We show that the normalized matched filtering is a reasonable choice for detection of common carotid artery in ultrasound images.
A new technique to compute the coupling between non-identical resonators has been presented in this paper. The proposed technique has been used to compute the coupling between coaxial combline ...resonators coupled magnetically. The proposed technique has been found to be computationally much faster than the traditional iterative technique. The computed results have been found to be in good agreement with the measured results.
In this paper, a bandstop frequency selective surface is devised using coupled split ring resonators. A four-SRR unit cell is the building block of the FSS. Split rings arranged in a round robin ...fashion gives polarization insensitive transmission characteristics. A modified structure is proposed to eliminate the dependence of the transmission characteristics on the angle of incidence. A considerably good performance was obtained for oblique incidence up to 75° and a 40% size reduction is also achieved. The structure can be further enhanced by improving the passband performance at oblique incidence.
