Dileep Kumar Upadhyay

An improved zeroth order resonator using left handed metamaterial

In this paper an improved version of zeroth order resonator (ZOR) using Left Handed Metamaterial (LHM) is reported, and its performance is compared with the earlier published ZOR. The resonator is designed based on microstrip technology using composite right left handed transmission line (CRLH TL) approach. The conventional ZOR is designed based on the CRLH TL along with two coupling slots at the input and output ports, whereas the proposed design of ZOR is based on coupling capacitors. Use of coupling capacitor in place of coupling slot improves resonance characteristic of ZOR in terms of return loss and insertion loss and also increases the operational bandwidth. The measured resonant frequency, return loss, insertion loss and fraction bandwidth of the proposed 1.5- unit cell ZOR are 1.5 GHz, -26.31 dB, -0.42 dB and 20.66% respectively, whereas for the conventional 1.5-unit cell ZOR these measured parameters are 1.8 GHz, -6.63 dB, -9.09 dB and 0.77% respectively. The frequency parameter and performance of the resonators are evaluated by full-wave electromagnetic simulator, IE3D, based on method of moments (MoM) and all these results are verified by measurements.

Design of Full Scanning Miniaturized Antenna Using Left Handed Materials

An improved version of full scanning antenna using Left Handed Metamaterial (LHM) is reported in this paper. The antenna profile is designed based on microstrip technology using balanced composite right left handed transmission lines (CRLH TL) approach. Conventional LC network representation of the CRLH TL uses cascaded combination of inter digital capacitor (IDC) in series and vias to the ground plane at the stub ends in shunt, whereas in this article the design of full scanning antenna using WBIDC is reported and its performance is compared with conventional IDC based full scanning antenna. Use of WBIDC improves high frequency performance of antenna by reducing undesired resonances at lower frequency end. A simple technique is also used to miniaturize the proposed antenna profile. Dispersion diagram of the balanced CRLH TL based dominant mode leaky wave antenna (LWA) shows the capability of backfire (-90o< e <0o) to broadside (e = 0o) and to endfire (0o< e <90o) scanning. Radiation patterns confirm the full scanability of the antenna and it also shows the designed structure has reduced sidelobes in the endfire radiations. The return loss characteristic of the reported antenna structure shows an increase in the antennas operational bandwidth. The frequency parameter and performance of the antenna are evaluated by full-wave electromagnetic simulator using Ansoft Designer and these parameters are verified by another full-wave electromagnetic simulator using IE3D.

Reconfigurable patch antenna for bandwidth control for point to point communication

Bandwidth reconfigurable microstrip rectangular patch antenna with operating frequency (ƒc), 5.8 GHz has been presented in this paper. Network morphing method has been used to achieve reconfigurability. The bandwidth (BW) of the antenna varies from 107 MHz to 153 MHz i.e. a bandwidth variation of 46 MHz at almost constant frequency is observed. The VSWR achieved in this structure is 1.19. All this is confined within a compact size of 17.8 ×12.1 mm2.

Frequency reconfigurable bandpass filter for IMT-A applications

A spiral resonator reconfigurable microstrip band pass filter is presented in this manuscript. The filter provides control variation in resonance frequency (ƒc). The variation in center frequency of the proposed design is noted from 3.40 – 3.77 GHz. The filter is designed to work at LTE-42 band to support IMT-A applications. The size of the proposed spiral structure is 14.6 × 5.5 mm2.

Improvement of performance parameters of rectangular patch antenna using metamaterial

In this paper, metamaterial superstrate is proposed to enhance the performance parameters of conventional rectangular microstrip patch antenna. The metamaterial is designed using proposed diagonally connected square split ring resonator (DC SSRR). The designed DCS SRR shows the negative values of refractive index for broadband frequency band, 5.0 GHz to 12 GHz. Use of metamaterial superstrate on conventional rectangular microstrip antenna improves the return loss by 18 dB and enhances the gain, bandwidth and radiation efficiency by 1.2 dBi, 28 MHz and 17.5% respectively. The permittivity, permeability and refractive index of metamaterial are numerically computed using MATLAB. All performance parameters of antenna and S-parameters of DC SSRR are obtained using commercially available full wave electromagnetic simulator HFSS based on finite element method and verified by measured results. Good agreement is found between simulated and measured results.

Reconfigurable Bandpass Filter for use of 2.7– 3.1 GHz radar spectrum

A bandwidth reconfigurable Microstrip Bandpass Filter (BPF) for air traffic management and air defense radar system has been presented in this paper. The proposed structure achieves a fractional bandwidth of 3.24% at constant resonance frequency 2.9 GHz with minimum and maximum bandwidth as 366 MHz and 460 MHz respectively. All this is achieved in a compact size of 42.85 × 26.725 mm2.

Bandwidth reconfigurable patch antenna for next generation wireless communication system applications

A Bandwidth reconfigurable microstrip antenna has been presented in this paper. Dual layer circular patch antenna structure has been used. Geometrical variation in horse shoe structure used as lower patch is responsible for controlled bandwidth variation. The proposed antenna structure provides bandwidth variation from 90.99 MHz to 144 MHz at constant resonant frequency of 3.4GHz.

Design of Miniaturized Dominant Mode Leaky-Wave Antenna Using Left Handed Metamaterials

A new miniaturized dominant mode planner leaky-wave antenna is proposed. This antenna is a transmission line structure with radiating wavenumber increasing from negative to positive values, providing backward to forward scanning capability as frequency increases. The antenna profile is designed based on microstrip technology using balanced composite right left handed transmission lines (CRLH TL) approach. The balanced CRLH TL is designed based on cascaded combination of inter digital capacitor (IDC) in series and vias to the ground plane at the bent stub ends in shunt. Bent stubs are used in each section for the purpose of miniaturization. Dispersion characteristics of CRLH TL shows the left handed region, right handed region and balanced design of composite right left handed metamaterial. The radiation pattern of the proposed antenna confirms the full scanability i.e. backfire-to-endfire scanning capability of the antenna. The frequency parameter and performance of the antenna are evaluated by full-wave electromagnetic simulator using Ansoft Designer and all frequency parameter and performance are verified by another full-wave electromagnetic simulator using IE3D.