Trushit Upadhyaya

Negative refractive index material-inspired 90-deg electrically tilted ultra wideband resonator

Abstract. A negative refractive index material loaded patch antenna is proposed for ultra wideband applications. The wideband operation has been achieved by creating a defected ground plane with a CNC shaped split ring resonator. The defected ground plane CNC resonator also exhibits a 90-deg electrical tilt. Two additional slots are engineered in the patch antenna for further bandwidth enhancement. A −10  dB bandwidth with an order of 57.89% has been achieved with a peak gain of 5.37 dBi at a 5.5 GHz resonant frequency. Measured results demonstrate good agreement with simulated results.

Novel stacked μ -negative material-loaded antenna for satellite applications

An engineered novel tunable dual-band metamaterial antenna based on stacked split ring resonator (SRR) array is presented. The μ-negative SRR array present at two sublayers of stacked microstrip patch antenna substrate adds tuning capability to the antenna with marginal trade-off between antenna gain and cross-polarization. If the size of resonator element is considerably smaller than resonance wavelength, ideally lesser than λ/10, the resonator would support the resonating mode of antenna. Compact SRR array embedded in radiator facilitate the antenna tuning to intended allocated spectrum of L5- and S-band frequencies without modifying external dimensions of patch antenna, which in turn helps the satellite payload design. The variations in SRR array dimensions and inter-element spacing are subsequently utilized to maintain the antenna gain and voltage-standing wave ratio. The proposed design of inset fed antenna, matched at 50 Ω, was validated by experimental results and it is suitable for global positioning satellite applications.

Miniaturization of Tri Band Patch Antenna Using Metamaterials

Fulfilling need of compact, cheap and efficient antennas is immensely sought after by the technocrats. The patch antennas are providing necessary support as planar antennas for satellite and radar communications. The Left Handed Materials, Metamaterials, allows us to tweak the properties of electromagnetic waves and hence optimizations in physical properties of patch antennas. Majority available literature presents negative refraction in upper microwave regime, however, presented design offers benefits of metamaterials in lower Gigahertz domain. Through numerous simulations iterations, presented metamaterial inspired patch offers tri-band resonance as target frequencies of LEO and MEO satellites operations for dual transmit and single receive frequencies. The presented novel & unreported design offers miniaturization of patch antenna by 80% with minimum return loss of -20 dB having ample flexibility in tuning the antenna resonance.

Analysis of Multiband Behaviour on Square Patch Fractal Antenna

This paper on fractal antenna design exhibits details of fractal geometries developed to get multi band behavior of patch resonator antenna. Research on the performance of the fractal perimeter and fractal area alterations of patch antenna are presented. The behavior of patch resonator for various incremental steps in fractions, results in considerable rise in number of resonant working frequencies with improved bandwidth. The presented antennas multi band nature is design for Aeronautical radio navigation at 2.7-2.9 GHz and Aeronautical/Maritime radio navigation 9.0-9.3 GHz with captured downlink data of fixed/mobile satellite in S band and C band.

Lunar surface crater topology generation using adaptive edge detection algorithm

The probability of precise soft landing on the lunar surface could be significantly increased by using craters as a navigational landmark. This article aims at the edge information of crater for lander navigation. First, histogram of an image is calculated and adaptive Gaussian filter is applied. Then adaptive canny algorithm is applied to detect edges of craters at different illumination. The craters are extracted by the mechanism of paring the selected valid edges followed by pattern fitting. These detected craters are used as navigational landmarks and for velocity estimation of the lander. Experimental results show the adaptive ability of algorithms for crater detection at different illuminations and different terrains. Craters at high illuminations are also efficiently detected. These detected craters are matched with the reference crater database by use of pattern matching algorithm for horizontal velocity calculations.

DUAL-BAND POLARIZATION-INSENSITIVE METAMATERIAL INSPIRED MICROWAVE ABSORBER FOR LTE-BAND APPLICATIONS

In this paper, the design, simulation and measurement of a dual-band polarizationinsensitive metamaterial inspired microwave absorber are presented. The unit cell is composed of two concentric closed ring resonator (CRR) structures forming octagonal rings which are carved on an FR-4 dielectric substrate to give maximum absorption at dual frequencies of 2.09 GHz and 2.54 GHz. At these frequencies, the minimum reflection coefficients of −29.15 dB and −18.76 dB are achieved with absorption rates of 99.88% and 98.67% and narrow 10 dB bandwidths of 2.62% and 2.76%, respectively. Microwave absorption property of the proposed absorber structure is simulated by setting the perfect electric boundary conditions in four planes whose surface normal vectors are directed perpendicular to the wave propagation direction. These numerical computation settings replicate the rectangular waveguide to be used in the experimental measurements for the comparison between the simulated and experimental results. It is experimentally verified by the waveguide measurement method that the absorption rates about 99% are achieved for dual bands with polarization insensitivity thereby meeting the absorption requirements of LTE-band frequencies for a real time microwave absorber based energy harvesting systems.