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Purpose: The design, fabrication and experimental validation of defected microstrip structure (DMS) are proposed to address the problem of near-end crosstalk (NEXT) and far-end crosstalk (FEXT) between the microstrip transmission lines in a printed circuit board. Design/methodology/approach: The proposed DMS evolved with the combination of spur line (L-shaped DMS) and U-shaped DMS topologies. This technique reduces the strength of electromagnetic coupling and suppresses crosstalk by optimizing the capacitive and inductive coupling ratio between the linked microstrip lines. The practical inductance value is much more significant in DMS than in defected ground structures (DGS), but the capacitance value remains the same. Findings: A DMS unit is etched on the aggressor microstrip line instead of the DGS circuit. Because there is no leakage via the ground plane and the circuit size is far smaller than with DGS, the enclosure issue is disregarded. DMS structures have a larger effective inductance and are resistant to electromagnetic interference. A tightly coupled transmission line structure with minimal separation between the coupled microstrip line is designed using DMS. Further research must be conducted to improve the NEXT, FEXT and spacing between the transmission lines. Originality/value: Simulation and actual measurement results show that the proposed DMS structure can effectively suppress crosstalk by analysing the S-parameters, namely, S_12, S_13 and S_14, with measured values of 1.48 dB, 20.65 dB and 21.099 dB, respectively. The data rate is measured to be 1.34 Gbps as per the eye diagram characterization. The results show that the NEXT and FEXT are reduced by approximately 20 dB in the frequency range of 1–11 GHz for mixed signals. The substantial measured results in the vector network analyser coincide with the computer simulation technology microwave studio suite simulation results. [ABSTRACT FROM AUTHOR]

Currently, the inspection and verification of vehicle-related information are done by police inspectors using camera-based systems or manually. Though integrating video technology is more advantageous than manual operation, they do not perform accurately due to bad weather or driving styles. This paper presents the design of a compact, durable, battery-free, UHF RFID tag with enough memory to carry necessary information for automatic identification of traffic law enforcement applications. The vehicle owner can also be alerted when the tag is detected due to the visual indication facility. This tag’s novel feature includes adapting a modified T-match structure to match the highly capacitive impedance of the chosen RFID sensor chip, i.e., Farsens Rocky100. In contrast to existing designs, the proposed tag contains no extra lumped components that necessitate an external impedance matching circuit. Instead, the input impedance was matched using an advanced T-match topology and by optimizing the antenna’s geometrical features. Simulations were done in Ansys HFSS (High-Frequency Structure Simulator) whereas the dimensions of all the printed elements were fine-tuned using parametric optimization. The tag was fabricated on a low-cost FR4 substrate and measured. The tag with an overall size of 110 × 25 × 2.4 mm³ can be detected by a conventional UHF RFID reader within a range of about 0.2 m–1 m. Due to the loop configuration, the tag exhibits a confined detection range while operating well within short ranges. [ABSTRACT FROM AUTHOR]

In this paper, a quad-port multiple-input multiple-output (MIMO) semitransparent antenna is designed for automotive applications. The transparent soda lime glass substrate is used in the prototype antenna for windshield applications, and the radiator is nontransparent copper metal. The unit cell radiator of the MIMO antenna is similar to the "NISSAN automobile-like" logo. The proposed MIMO antenna has a −10 dB impedance bandwidth of 3.4 to 11 GHz. The edge-to-edge distance between the elements in the MIMO configuration is 6 mm. The antenna elements are perpendicularly oriented to offer dual (horizontal and vertical) polarization, which aids in providing better isolation and good signal reception in all directions. The isolation between the resonating elements is greater than 15 dB without the use of any decoupling structure. The diversity metrics are examined in order to gain a better understanding of the MIMO antenna performance. The envelope correlation coefficient (ECC) is less than 0.01, diversity gain (DG) is greater than 9.98 dB, and the total active reflection coefficient (TARC) and channel capacity loss (CCL) are less than −10 dB and 0.07 bits/s/Hz, respectively. The quad-port MIMO antenna offers transparency of 52.26% over the entire area. The proposed antenna could be suitable for automotive applications such as intelligent transportation systems (ITS), vehicular communications, and the automatic vehicle identifier (AVI). [ABSTRACT FROM AUTHOR]

A low-profile multi-polarized MIMO ultra-wideband antenna suitable for body-centric communications is reported. MIMO configuration is achieved using the symmetric heptagonal monopole (SHM) antenna, a mirrored SHM antenna, an asymmetric ruby-shaped monopole (ARSM) antenna, and a mirrored ARSM antenna placed over the modified C-shaped ground plane (MCGP). The proposed antenna elements are designed to achieve resonance for the entire ultra-wideband frequency range. The SHM antenna is coupled with a co-planar waveguide to produce linear polarization. An ARSM antenna generates circular polarization utilizing an asymmetric geometry both in the radiator and a truncated ground plane. Both the SHM antenna and an ARSM antenna are aligned face-to-face over an MCGP plane and good isolation >15 dB is realized between the antenna elements. The gain and total efficiency for linear polarized and the circularly polarized antennas are 3.05–4.8 dBi/48–66% and from 2.8 to 5 dBic/52 to 70.5%, respectively. The specific absorption rate values are evaluated to understand their suitability for WBAN communications. [ABSTRACT FROM AUTHOR]

There is a strong demand for compact and multiband antennas as wireless technologies become more integrated into automobiles. These antennas must be able to serve multiple services without compromising the size and installation space. In addition, the antenna incorporated should not affect the aesthetic appearance of the vehicle. This paper presents a compact multiple-input-multiple-output (MIMO) antenna working at 2.45 GHz (Wi-Fi/Bluetooth/RFID) and ultra-wideband (UWB) frequencies. A basic rectangular monopole with a self-complementary structure is used to design the antenna element. The size of the antenna element is 20 × 22 mm2. The proposed MIMO cube is developed with four antenna elements in cubical orientation to achieve compactness and better isolation. The overall dimension of the MIMO antenna is 35 × 22 mm2. The diversity antenna shows impedance bandwidth of 2.4–11.5 GHz and isolation of more than 20 dB. The envelope correlation coefficient (ECC) of the MIMO antenna is less than 0.2, diversity gain (DG) is greater than 9 dB, and total active reflection coefficient (TARC) and channel capacity loss (CCL) are less than −10 dB and 0.4 bits/s/Hz, respectively. The gain and efficiency are found to be greater than 1 dBi and 72%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a pattern diversity UWB antenna for Wireless Body Area Network (WBAN) communications. Pattern diversity antenna comprises two antenna elements with directional and omnidirectional patterns suitable for off-body and on-body communications respectively. Several broad-banding techniques such as Co-Planar waveguide, parasitic patches, and cavity resonant techniques are incorporated in microstrip antenna to achieve an ultra-wideband of 7.5 GHz (3.1 to 10.6 GHz) with a directional pattern. Monopole radiator topology is utilized to achieve a UWB frequency range of 2.6–10.6 GHz with an omnidirectional pattern. Pattern diversity is achieved using an orthogonal arrangement of the antenna elements in a compact size of 40 mm × 34 mm, maintaining the isolation >20 dB between the antennas. Gain varies from 2.2 to 4.6 dBi and 2.5 to 7.5 dBi for omnidirectional and directional antenna respectively. The simulated radiation efficiency for the directional antenna and the omnidirectional antenna are 74–86% and 52–66.5% respectively. The proposed design provides a good diversity performance in the entire UWB bandwidth with ECC<0.1 and a diversity gain of approximately 10 dB. SAR impact evaluated under various conditions is found to be <1.6 W/Kg for 1 gram of tissue. [ABSTRACT FROM AUTHOR]

This paper presents a reconfigurable loop-based filter performing compound reconfiguration. The designed filter is capable of functioning as a bandstop or bandpass filter by a simple approach of cascading the resonator to the transmission line connecting source and load. Shifting of operating frequencies is characterised by switching between a loop and a C-shaped resonator. To demonstrate the working of the proposed concept, a compound reconfigurable filter operating at 1.5 GHz and 1.6 GHz is developed. The filter is developed on a compact layout of size 0.27 × 0.12 λg2. The proposed prototype is fabricated and measured for real-time validation. [ABSTRACT FROM AUTHOR]

In this communication, a compact dual‐element MIMO antenna with decoupling structure has been proposed for handheld devices. The proposed decoupling structure acts as a resonator and as a decoupling structure. The proposed antenna consists of nested slots in the radiator and it supports the application such as LTE, WLAN, Wi‐Fi, and WiMAX. The total size of the antenna is 30 mm × 10 mm. The impedance bandwidth of the antenna is 300/400/700 MHz, respectively. The decoupling structure consists of a feed line printed on one side of the substrate and swastika‐shaped array on another side. The power fed to the feed line coupled to the swastika‐shaped array for achieving the operating bands at 0.9 GHz and (8‐10) GHz. Meanwhile, the decoupling array provides isolation more than 20 dB at (2.3‐2.6) GHz, (3.4‐3.8) GHz, and (5.15‐5.85) GHz. The edge to edge spacing between the antennas is 10 mm. The percentage bandwidth of the antenna is 12.2/11.1/12.7/22.2%. The MIMO performance metrics such as envelope correlation coefficient, effective diversity gain, apparent diversity gain, and mean effective gain are evaluated. The proposed antenna is fabricated and tested. The measured results correlate with the simulated results. [ABSTRACT FROM AUTHOR]

The design, development, fabrication, and testing of a wideband reflectarray antenna with a novel concentric ring element operating over Ku/K band frequencies is presented in this paper. The element characterization is performed using the infinite array approach and is inferred that the proposed unit cell offers a higher phase variation of 643° by changing the size of the concentric rings. The proposed reflectarray antenna has a circular geometry and is constructed using 437 elements with an element separation of 0.43λ0. The proposed reflectarray offers a 3 dB gain bandwidth of 35% (15–21 GHz). The aperture efficiency is estimated to be 58.78% at 16.5 GHz. The prototype reflectarray is fabricated and tested to validate the simulation results. The measured peak gain of the reflectarray is 28.4 dBi with a side lobe level of −17.6 dB. The measured cross‐polarization level is less than −32 dB. Furthermore, it is inferred that the proposed unit cell has a reduced maximum phase sensitivity of 246°/mm with a gain selectivity of 6 dB at the lowest operating frequency. The proposed broadband reflectarray with enhanced performance characteristics is suitable for application in satellite communication and aeronautical radio navigation. [ABSTRACT FROM AUTHOR]