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This paper presents method for integrating two dual port multiple input multiple output (MIMO) antennas on a common substrate based on substrate integrated waveguide (SIW) technology. One of the dual port MIMO antennas (MIMO_1) resonates at 31.2 GHz with an impedance bandwidth of 1 GHz while the other dual port MIMO antenna (MIMO_2) exhibits an impedance bandwidth of 925 MHz and resonates at 36 GHz. The radiators etched on the SIW cavities are complementary slotted annular rings (CSAR). Isolation between the ports is more than 20 dB which is inherently achieved by SIW cavity backed structures. The MIMO antenna realized at 31.2 GHz exhibit a peak realized gain of 8.5 dBi while the MIMO antenna realized at 36 GHz displays a peak gain of 9.8 dBi. The diversity gain of both the MIMO antennas is around 9.9 dB and the envelope correlation coefficient (ECC) of the MIMO antenna realized at 31 GHz is below 0.004 while the ECC of MIMO antenna at 36 GHz is below 0.006. It is also confirmed that simulated results closely correlate with the measurement results. [ABSTRACT FROM AUTHOR]

The sequential layout of a portable ultra-wideband (UWB) monopole antenna, transforming into a compact band-notch (3.15–4.3 GHz rejecting the Wi-Max and the C-Band) multiple-input multiple-output (MIMO) antenna is described in this paper. The diversity layout is designed within a compact size of 39 (l) × 18 (W) mm2. Due to the opposite orientation of the two radiators in the diversity configuration and the use of a rectangular parasitic strip near the feed lines, high and wideband isolation (of >20 dB) is attained over the entire UWB spectrum. The proposed layout depicts a stable omnidirectional radiation pattern and a maximal gain of 1.82 dB. The envelope correlation coefficient (ECC) is found to be below 0.18 for the entire UWB spectrum. Empirical verifications in terms of vital diversity parameters and analogy with competing layouts strengthen the candidature of the intended MIMO layout for UWB wireless portable applications. [ABSTRACT FROM AUTHOR]

This paper presents a miniaturized Quad-Port MIMO antenna for UWB application. Employing Characteristic Mode Analysis, the single element UWB antenna is analysed to achieve a compact design. Using the Theory of Characteristic Mode, the significant modes and their current distribution are analysed, which helps to modify the radiator and ground plane to generate more significant modes to yield a wider frequency band. Four circular-shaped radiators with tapered feeds are placed orthogonally on the FR4 substrate to improve isolation, and partial ground planes are located on the opposite surface. Furthermore, a modified Pattee-cross-shaped parasitic element is introduced between the antenna elements and shorted with the ground planes via metallic shorting pins. This novel technique improves isolation compared to the conventional integration method of the partial ground planes through strip lines. The proposed antenna achieves less than −20 dB mutual coupling over most of the frequency band ranging from 2.51–18 GHz. [ABSTRACT FROM AUTHOR]

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 design concept that uses multi-layer metasurface structures to design and develop bandpass filter screens is proposed. The unique proposition of the work lies in the control of transmission bandwidth of such metasurface screens, which has been obtained by sequential arrangement of unit cell layers, that comprise of Minkowski fractal-shaped unit cells and its complement. This reconfigurability of the structure is achieved without changing the geometry of the unit cell design, rather by stacking the layers in different configurations, or even by changing the substrate thickness, leading to the capability to obtain either narrowband or broadband filtering screens as per the requirement. An equivalent circuit model is proposed to explain such behaviour. Two configurations of stacked complementary surfaces, namely the Patch-Slot-Patch (PSP) and the Slot-Patch-Slot (SPS) designs have been investigated. The PSP structure on a thinner dielectric substrate offered dual band resonance with distinguishable transmission peaks, whereas the same configuration on substrate of increased thickness offered wider transmission bandwidth (45.5% to 50.5% percentage bandwidth). In comparison, the SPS structure offered much narrower transmission bandwidth (varies between 4.7% to 8.16%). The effect of changing the periodicity of the unit cell elements, without altering the fractal unit cell dimensions, has been described, through which one can control the band of operation and roll-off performance of the screens. The simulation results are found to be in good agreement with the measured results of the fabricated prototypes. [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]