Volume 75, Issue 1-2

A multi spiral split ring resonator based sensor is proposed for the characterization of the dielectric properties of a water ethanol mixture. The use of a narrowed microstrip line to excite the multi spiral resonator allows enhancement of excitation current and increase the sensitivity of the sensing area. Good agreement will be presented between theoretical and measured electrical parameters of the resonator in a wide frequency range from 2 to 5 GHz. The proposed sensor shows high sensitivity, miniature size, and affordable cost and above all laboratory-on-chip compatibility important for a large-scale production.

The performance of a generalized mixed free-space-optical (FSO)/millimeter (mm)-wave radio-frequency (RF) two-hop link model is investigated in this work. The first-hop FSO channel considers the influence of path loss, atmospheric turbulence which is modeled by the gamma–gamma (GG)-distribution, and generalized misalignment errors which incorporate the effects of non-zero boresight errors, different jitter standard deviations along the horizontal and vertical directions, and correlation between the horizontal and vertical displacements. The second-hop RF link is modeled by an extended-generalized- K (EGK) distribution which is a versatile distribution and can characterize various fading conditions in mm-wave wireless channels where the transmission frequency is in excess of 60 GHz, and considers non-homogeneous propagation, interference effects due to multiuser transmission, multipath fading and shadowing effects observed in mm-wave RF wireless channels. The considered system employs fixed-gain amplify-and-forward (AF) relay-assisted transmission. The statistical characteristic for the end-to-end SNR, i.e., cumulative distribution function (cdf), is obtained for the considered system model in this work. Based on the obtained result for cdf, the outage and error performance is evaluated, and closed form expressions for the same are derived. The derived analytical results have been illustrated through numerical plots.

This paper presents a novel E armed dipole antenna for System On Chip (SOC) applications in the Sub-THz frequency band. The antenna is printed on a corrugated silicon substrate which suppresses surface waves and provides high efficiency and gain. The corrugated substrate also provides a better impedance matching. The antenna has a simulated gain of 5.4 dBi and 3 dB beam-width of 83.5 degree. The proposed antenna also has a very high radiation efficiency of 90%. Antenna resonates at 141.8 GHz and has an approximate −10 dB bandwidth of 1 GHz. To investigate the effects of different design parameters, some parametric analysis has been carried out and results have been shown. An equivalent circuit model has been reported. The equivalent circuit has been used to find the resonant frequency of the proposed dipole. The deviation of simulated and calculated resonant frequency is less than 0.5% which is well within the acceptable limits for antennas operating in mm-wave and sub-THz frequency band. This antenna is well suited for SOC, radar on-chip, high gain arrays, etc.

In this article, a simple design of stacked radiating system with enhanced gain, impedance bandwidth, and radiation efficiency for mobile base station application is presented. The proposed antenna consists of a driven patch with a semicircular parasitic patch printed on the bottom layer and five parasitic patches printed on the top layer. The driven patch is feed by a co-axial probe and both the layers are separated in air. The second layer has four truncated circular parasitic patches on one side and one circular patch on the other side to enhance the directive gain acts as a directive reflector. This staked system encompasses some prominent features such as wide bandwidth, good gain, low profile, better radiation efficiency simple design, and integration for the mobile base station. Meanwhile, this configuration exhibits a bandwidth of 2 GHz with the minimized volume is 0.75 λ 0  × 0.75 λ 0  × 0.08 λ 0 . Experimentally validated results have an average and peak gain of 10.7 and 12.7 dBi, impedance bandwidth of more than 30.7% for |S 11 | < −10 dB, and radiation efficiency of above 86%. The proposed stacked radiating system finds its applications in Wi-Fi, WLAN, Wi-Max, Indoor UWB, and Marine Radar applications.

A 3 × 3 slotted circular Electromagnetic Band gap based Metasurface (SCEBG-MS) has been presented in this article, which enhances the performance of a circularly polarized (CP) patch antenna by improving its impedance bandwidth, axial ratio bandwidth and gain. The proposed antenna is having a low profile of 0.065  λ o ( λ o is the free-space wavelength at center frequency of 6.16 GHz) with ground size selection of 30 × 30 mm. The prototype antenna achieves a measured −10 dB impedance bandwidth of 37% (5.02–7.30 GHz) and measured 3-dB axial ratio bandwidth of 5.9% (5.24–5.56 GHz). Furthermore, the antenna yields a good peak gain of 6.6 dBic in the CP bandwidth which makes it a promising candidate for Wireless Local Area Network (WLAN) applications. Experimental results obtained from the fabricated prototype closely matched with the simulated results.

In this article, Terahertz spherical dielectric resonator antenna (DRA) is mathematically formulated and simulated at 511 THz for LiDAR and retinal photoreceptor applications. Titanate DR element is used at optical design frequency. It is validated with good S 11 , radiation pattern and 5.6 dBi gain plots using HFSS simulator. Unique mathematical formulation on super directivity and radiated states is formulated for the first time. The proximity coupled feed is used with laser Gaussian beam excitation. The silver nano waveguides is used to provide feed mechanism to terahertz DRA. This DR design at optical frequency can be used for wireless sensing and communication applications. It has novel geometry.

Compact antennas with robust on-body performance are achieving more interest for wearable sensor nodes. In this paper, a modified aperture coupled multiple input multiple output (MIMO) antenna operating at 2.45 GHz industrial scientific and medical (ISM) band is presented for wearable devices. 8-shaped radiator with L-shaped ground slot is used to miniaturize the antenna dimensions. A dielectric reflector is added below the antenna to reduce the back radiations towards the body tissue. On-body performance is analysed on three layered equivalent tissue phantom model. Antenna shows reflection coefficient of −40 dB, efficiency of 58% and directivity of 6.7 dBi when operated in close proximity of body tissue with dielectric reflector. unidirectional radiation pattern and low specific absorption rate makes antenna suitable for on-body communication. Further, diversity performance is measured in terms of envelope correlation coefficient (ECC) and diversity gain (DG). Value of ECC is 0.045 and DG is 9.7 dB at 2.45 GHz. Antenna robustness is examined by bending the structure along x -axis. Performance of the proposed structure makes it a suitable candidate for on-body communication.