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A closely confined coplanar waveguide (CPW) fed MIMO antenna sheltering the entire ultra-wideband (UWB) spectrum with high isolation as well as dual-band rejection attributes is presented and evaluated. The intended wideband multiple-input multiple-output (MIMO) radiator embodies a pair of similar planar monopole elements (PME) together with the integration of the ingredients like a defected ground structure with Koch fractal boundaries, parasitic strips, cross-linked C-shaped parasitic resonators, and a Hilbert fractal neutralization line. The suggested UWB MIMO antenna houses an extensive bandwidth spanning between 2.64 and 12 GHz, sharply rejecting a pair of bands centered at 3.3 and 4.5 GHz. The wideband diversity antenna is realized in a closely packed measure of 26.50 mm (L) × 29.84 mm (W). A minute inter-element spacing of 0.51 mm is attained with the suggested layout. The numerical and experimental investigations of vital diversity parameters such as the envelope correlation coefficient, mean effective gain, total active reflection coefficient, as well as multiplexing efficiency depict high diversity performance. The consistency amidst the simulation as well as the empirical results recommends the worthiness of the intended antenna for handy UWB and UWB MIMO systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach for simultaneously correcting multiple degraded patterns under the failure condition of time-modulated linear arrays is proposed. The approach is based on the use of trapezoidal pulse with non-zero rise/fall time to control the switching status of the radio frequency switches that enables ON-OFF keying modulation of the array elements. After deriving a closed form expression of harmonic power loss and through the in-depth analysis, it is explored that the proposed trapezoidal pulse, because of having non-zero rise/fall time, provides less undesired harmonic power loss as compared to the conventionally used rectangular pulse with ideally zero rise/fall time. With the aim of reconstructing the degraded patterns with improved directivity and suppressed higher sideband power, three pulse-switching strategies based on rectangular and trapezoidal pulse have been employed, and their comparative performances prove the superiority of the proposed approach. [ABSTRACT FROM AUTHOR]

In missile test ranges, complex missions demand precise trajectory generated by radar. Both the radar and Global Navigation Satellite System (GNSS) signals are affected by atmospheric effects, degrading their accuracy and performance. The Indian Regional Navigation Satellite System/Navigation with Indian Constellation (IRNSS/NavIC) transmits signals in the S-band together with the L-band. This paper presents a novel experimental technique to improve the tracking accuracy of S-band radars using the concurrent NavIC S-band signal. The ionospheric delay using the NavIC S-band signal is calculated first, and the results are used to improve the trajectory data of simultaneously operating S-band radars. This is a unique application of the NavIC S-band signals apart from its conventional usage. During a launch mission, for low elevation angles, the ionospheric error is found to be ~130 m while at higher elevation angles the error values are found to be ~1–3 m. The concept is validated using data from a missile test mission. This report on the use of S-band GNSS signals for the correction of S-band radar range data offers a clear advantage of simplicity and accuracy. [ABSTRACT FROM AUTHOR]

A compact ultrawideband (UWB) bandpass filter (BPF) is designed by harnessing the efficacy of a Pythagorean tree fractal shape stub-loaded resonator. The design inherently provides the passband transmission poles, which make it convenient to be used in wide passband filtering circuits. The number and the position of the resonating modes can be controlled by increasing the iterations of the Pythagorean tree, as analyzed using odd- and even-mode analysis. Design steps of the BPF are detailed. The designed UWB BPF takes up a small circuit area of (12.13 × 9.59) mm2. The proposed design is fabricated and measured to verify the simulated results. The stopband is extended up to 17.5 GHz with a maximum attenuation of 15 dB. [ABSTRACT FROM AUTHOR]

A compact antipodal Vivaldi antenna with superwideband characteristics is presented in this paper. For improved matching of input impedance at lower frequency region, techniques like binomial tapering of outer edges, binomial slit loaded outer edge, and protruded binomial tapered stub loading have been adopted. The antenna operates in a wide frequency range from 2 to 20 GHz. Experimental results show, stable radiation pattern with peak realized gain of more than 8 dBi, group delay within 1 ns, 164% fractional bandwidth, radiation efficiency of more than 90%, which are in good agreement with the simulated results. The compact size of the proposed antenna (1.14λ0 × 1.21λ0) with wide frequency bandwidth and directional radiation characteristics make it suitable for through-wall radar and medical imaging applications. [ABSTRACT FROM AUTHOR]

A new class of switchable bandpass filter using PIN diodes is presented in this paper. The design aims at achieving a multistate switchable bandpass filtering characteristics between the passbands centered at 2.4, 3.5, and 5.2 GHz. The proposed filter is designed by assembling two λ g /2 open-ended and four short-ended λ g /4 uniform impedance resonators. The open-ended resonator generates a fixed passband at 3.5 GHz, whereas the short-ended resonators loaded with PIN diodes are independently controlling the ON and OFF characteristics of the passband centered at 2.4 and 5.2 GHz. The transmission zeros around each passband are produced without employing any additional circuit. The filter sample is fabricated and tested for experimental verification. A good agreement has been observed between EM-simulated and measured results. The designed filter has a compact size of 0.20 λ g × 0.15 λ g at 2.4 GHz. [ABSTRACT FROM AUTHOR]

This paper presents, a dual-band bandpass filter using asymmetric stepped impedance stub loaded open loop resonator (OLR) for WLAN and WiMAX application. The outer OLR is realized to operate at lower passband of 2.45 GHz which is directly coupled to input and output ports whereas the asymmetric stepped impedance stub that loads the outer resonator contributes to 3.5 GHz passband. The introduction of asymmetric stepped impedance stub provides further control of improving the upper passband edge selectivity of second passband and in shifting the spurious modes away from second band thereby contributing to the wide upper stopband. The insertion loss is within 1.5 dB for each passband with 10 dB passband bandwidth of 250 MHz at both bands. A stopband up to 10 GHz is also obtained. A prototype is developed and the s-parameters obtained from electromagnetic simulation, equivalent transmission line model and measurement are in close agreement. The overall dimension of the filter is 25.45 × 15.89 mm2 which renders it a compact size. [ABSTRACT FROM PUBLISHER]

This paper presents a band-notched ultra-wideband bandpass filter by loading a short stub and an asymmetric step impedance stub in a uniform impedance resonator. The passband extends from 3.04 to 10.8 GHz frequency. The multimode resonator provides a sharp band edge with measured transmission zeros at 2.59 and 13 GHz. The later one is due to source load coupling. The passband insertion loss is within 1.5 dB. The embedded spiral resonator introduces a notch at 5.25 GHz with attenuation of 15 dB. The filter exhibits a wide stop band till 15 GHz. The in band and out of band performance obtained from full-wave electromagnetic simulation and measurement are in close agreement. [ABSTRACT FROM PUBLISHER]

In this paper a dual-band bandpass filter with sharp rejection is proposed. The filter is realized by using two half-wavelength stepped impedance resonators to operate at the passbands 2.5 and 3.5 GHz. To increase the band width further to about 45 MHz at the lower passband and 115 MHz at the higher passband, interdigital capacitors are introduced between resonator and input and output combining network. Measured insertion loss is about 1.45 and 1.7 dB at first and second passbands, respectively. A finite transmission zero in between two passbands at 2.84 GHz is realized to improve the selectivity of the filter. The design procedure to get highly selective response of the proposed filter is explicitly explained. An equivalent circuit model of proposed filter is developed that matches well with measured results. [ABSTRACT FROM PUBLISHER]

A dual wideband design of Sierpinski carpet fractal-shaped planar monopole antenna with a coplanar waveguide (CPW) feed is proposed in this letter. Wide impedance bandwidth of 22% at lower resonance from 4.88 to 6.08 GHz and 41.7% at higher one, which ranges from 9.5 to 14.5 GHz, is obtained. Measured realized antenna gain is around 5 dBi at the lower band centered around 5.5 GHz and are around 4.5 dBi at the higher band. A fabricated prototype is developed with good agreement between simulation and measurement. [ABSTRACT FROM PUBLISHER]