Search

This article presents a compact reconfigurable filter performing bandwidth reconfiguration covering the entire L‐band frequency range. The reconfigurable filter is developed using a C‐shaped resonator coupled to the source and load through varactor diodes. To reverse bias the diodes symmetrically both the diodes are fed with a common bias voltage. Hence the DC bias voltage is administered evenly to the diodes resulting is equi‐proportional coupling between the resonator and the nodes. This results in reconfiguring the bandwidth of the operating frequency. The designed filter is capable of tuning 3‐dB bandwidth from 0.613 to 1.353 GHz with the center frequency as 1.5 GHz. The percentage bandwidth of the filter is varied from 44.5% to 91.76%. The insertion loss offered by the filter is very less with the minimum value of 0.42 dB. The proposed filter is simple, compact and finds it application in power agile systems operating with different transmission power levels at different time instances. [ABSTRACT FROM AUTHOR]

This paper details the construction and working of a compound reconfigurable filter capable of frequency and bandwidth reconfiguration in the frequency range from 2 to 3 GHz. The switching between frequency and bandwidth reconfiguration is inherited by two PIN diodes. Bandwidth tuning is facilitated by tuning two transmission zeros individually using varactor diodes, giving flexibility in reconfiguring the upper and lower pass edges. The two transmission zeros are obtained using simple concentric square loop resonators. The maximum bandwidth obtained is 1.5 times the minimum bandwidth offered by the filter. Hence the filter can be used for dynamic bandwidth allocation. This prototype is fabricated and validated in real-time. The simulated and measured results are analogous to each other. [ABSTRACT FROM AUTHOR]

A microstrip bandwidth reconfigurable filtering antenna is implemented by simply tuning the transmission zeroes. The proposed filtering antenna is developed by integrating the filter characteristics into the 50 Ω microstrip feed line of the antenna through two independent coupled resonators. The energy coupling between the transmission line and the planar loop resonator and dual F shaped resonator generates the transmission zeroes. These transmission zeroes at specified lower frequencies are generated in order to provide better selectivity over the edges of the pass band to promote high suppression of interferences. The varactor diodes are explicitly loaded at distinct locations in the resonators to achieve bandwidth reconfiguration. The two transmission zeros are tuned between 1.6-1.9 GHz and 2.1-2.42 GHz respectively by varying the capacitance of the two varactor diodes with percentage bandwidth of 17.1% and 14.1% respectively to support mobile and wireless short range applications. The proposed filtenna provides insertion loss less than 3 dB with good impedance matching below 15 dB. [ABSTRACT FROM AUTHOR]

In this paper, a compact, single-section, Ultra-wideband (UWB) coupled-line coupler designed using concentric loop in the signal plane and defect in the ground plane is presented. Bandwidth enhancement is achieved with low coupling at the X-band satellite downlink range to improve the signal strength for defence applications. Return loss greater than 15 dB and isolation greater than 20 dB is achieved over the entire UWB band. The prototype is fabricated and tested to validate the simulation results. Further to detect the quality of the output signal, signal integrity analysis is performed and metrics such as error vector magnitude (EVM), magnitude and phase error, eye pattern, constellation plots and signal to noise ratio are presented for the proposed UWB coupled-line coupler. [ABSTRACT FROM AUTHOR]

In this manuscript, a novel uniplanar monopole antenna for Tablet computer application is proposed. Multiband resonance is obtained by introducing multiple radiating branches and meandered stubs connected to the main monopole. Further, the impedance bandwidth of the operating bands is enhanced by introducing coupled parasitic stubs in the ground plane. The antenna has impedance bandwidth of 20 MHz (0.45-0.47 GHz), 270 MHz (0.69-0.96 GHz), 2370 MHz (1.43-3.8 GHz), 1600 MHz (4.9-6.5 GHz) for LTE 450/700/2300/2500 MHz, GPS, WLAN, Bluetooth applications, WiMAX and Wi-Fi applications. The size reduction of the proposed antenna is 60% compared to existing antenna solutions for tablet devices. The percentage bandwidth of the antenna is 4.35/34.2/90.6/23.2% for the four operating bands, respectively. Furthermore, the obtained gain of the antenna is greater than 1.8 dBi with peak gain of 5.65 dBi, and the efficiency is greater than 75%. The proposed antenna is tested on the mock-up system consisting of large ground plane of dimension 200 × 150 mm. The antenna is fabricated, and the measured results are compared with simulated results. The SAR is computed and found to be less than 1.6 W/Kg. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the design and testing of a novel frequency reconfigurable microwave filter. The filter structure is composed of an all stop resonator coupled with C‐ and E‐shaped parasitic resonators. PIN diodes are located at suitable positions to achieve multi‐band reconfiguration from 1.2 to 3.2 GHz making the filter suitable for multiple wireless communication systems. The frequency and bandwidth of the filter are governed by the length of the resonators and coupling between the resonators and the transmission line, respectively. A sharp rejection of −30 dB is observed between the passbands. The proposed filter offers 56% size reduction with flat group delay performance. The prototype filter is fabricated and the simulation results are validated using experimental measurements. The measurement results show good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

This paper presents a miniaturized frequency selective surface (FSS) with stop band characteristics at the resonant frequency of 5.12 GHz. The unit cell size of the proposed FSS design is in the order of 0.095 λ×0.095 λ. The proposed unit cell is obtained by convoluting the arms of the basic swastika structure. The design provides fractional bandwidth of 9.0 % at the center frequency of 5.12 GHz in the 20 dB reference level of insertion loss. The symmetrical aspect of the design delivers identical response for both transverse electric (TE) and transverse magnetic (TM) modes thereby exhibiting polarization independent operation. The miniaturized design provides good angular independency for various incident angles. The dispersion analysis is done to substantiate the band stop operation of the convoluted swastika FSS. The proposed FSS is fabricated and its working is validated through measurements. [ABSTRACT FROM AUTHOR]

ABSTRACT This letter presents planar microstrip branch-line (BL) couplers with improved phase and amplitude stability bandwidth along with significant size reduction. The prototypes are designed to operate at 433 MHz frequency band suitable for ISM 433 MHz applications. The prototypes with symmetric polygonal modification (SPM) and asymmetric polygonal modification (ASPM) offer a wide quadrature phase bandwidth of 37.8% and 35.5% respectively, over which the phase imbalance is within 90°±5°. In SPM all four transmission lines of the BL coupler have been symmetrically modified to bring in 75.99% size reduction compared to the conventional design. Further asymmetric modification has been performed to bring an additional 12.34% size reduction, compared to symmetric, and providing an overall size reduction of 78.95% compared to conventional BL coupler. The prototypes are able to offer compactness without compromising much on the matching, transmission and isolation parameters. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1369-1374, 2016 [ABSTRACT FROM AUTHOR]

In this study, a modified antipodal Vivaldi antenna (AVA) with low cross-polarisation is proposed for ultrawideband communications. The bandwidth offered by conventional single petal AVA is enhanced by adding another petal. This dual petal antenna occupies a small volume of 60 × 60 × 0.8 mm3 and provides operating bandwidth from 2.4 GHz to frequencies >14 GHz. The proposed antenna configuration provides low cross-polarisation level which is <-15 dB over the entire operational band. The designed antenna offers realised gain >5 dB and an average group delay variation of 0.5 ns. The prototype antenna is fabricated and tested to validate the simulation results. [ABSTRACT FROM AUTHOR]

This communication presents a bandwidth-enhanced, compact, monopole antenna with modified ground plane for modern automotive ultra wide-band (UWB) applications. The proposed antenna has hybrid geometry and is constructed using half circular ring and half square ring. The ground plane of the fundamental radiator is curved and defected to improve the VSWR bandwidth. An extended ground stub is added to further enhance the bandwidth to suit the modern automotive requirements. The designed antenna covers 3.1–10.9 GHz frequency spectrum with \mathrm VSWR \leq 2. This antenna can be conveniently placed inside the shark fin housing or it can be printed along with the existing print circuit board (PCB) electronics nullifying the need for dedicated location for in-car communications. Furthermore, a simple two-port multiple input multiple output (MIMO) antenna is constructed and its diversity performance is estimated. The prototype is fabricated and tested for impedance and radiation characteristics. [ABSTRACT FROM PUBLISHER]

This paper deals with a novel miniaturized FSS with wide stop band characteristics for UWB applications. The proposed FSS consists of garland like design printed on either side of the dielectric substrate. The design provides a bandwidth equal to 3.5 GHz at -20 dB reference level of insertion loss which lies within the UWB range. The design delivers stable response for various angular incidences. In addition to this, the symmetrical nature of the FSS holds identical response for both TE and TM Mode of polarization. The proposed geometry is fabricated and its simulated results are validated with measurements. A comprehensive analysis is made by adjusting various parameters associated with the proposed design. [ABSTRACT FROM AUTHOR]