Krishnamoorthy Kandasamy

In this paper we present a dual band low cross-polarized periodic microstrip leaky wave antenna (LWA) based on the multi mode resonator concept (MMR). The structure is capable of frequency dependent backward dual-beam steering and fast forward beam scanning in the upper and lower operating band, respectively. A gap loaded microstrip line is used as a host transmission line to feed the combination of the periodic patch radiators on the top and the bottom etched slots leading to the generation of the forward and the backward space harmonics. The etched ring slots at the bottom surface of the structure are not only responsible for steering the beam in the backward direction in the bottom hemisphere in its upper band but also adds radiation diversity in the overall radiation mechanism in its two operating bands. The potential use of this antenna resides in its ability to produce in-plane fast forward beam steering suitable for autonomous vehicle navigation systems in its lower band and out-of-plane backward-symmetric dual beam steering in the upper operating bands, suitable for tracking in relay systems.

This paper presents a flexible antenna sensor on denim jeans fabric for H ₂ O sensing. A small defected ground structure is developed on the copper ground plane of the antenna. Graphene oxide is coated on the defected ground for sensor applications. The flexible antenna sensor with graphene oxide coated on a defected ground plane resonates at 5.52 GHz. The resonance frequency of the proposed antenna changes linearly with the H ₂ O content. The frequency sensitivity of the denim fabric antenna sensor is ≈ 203MHz/10%RH (relative humidity). The denim fabric antenna sensor has a measured phase sensitivity of 40 degrees per 10% RH. The flexible antenna sensor gives a linearity of 98.28%. The designed antenna sensor can distinguish between fresh and dried grapes by H ₂ O detection.

In this paper, a novel dielectric metasurface-inspired multi-beam directional Luneburg lens is proposed as a wireless power transfer medium at 5G mm-wave band. The lens is constructed using dielectric-based unit cells made up of a glide symmetric approach. It is connected with a set of microwave detector integrated multi-port tapered rectangular feeds to convert the received RF energy from different directions to DC power across a combined load. The proposed structure can be a potential candidate to harvest ambient energy from a wide coverage range of around 160° and produce a power conversion efficiency of about 76% for an input power of 14.9 dBm at 24 GHz.

Dual polarized printed multiple input multiple output (MIMO) antenna for Band 42 (3.4 - 3.6 GHz) with wave propagation models is presented. Polarization and spatial diversity are achieved by utilizing two printed bow-tie antennas in orthogonal orientation. The designed dual polarized antenna element with 2×2, 4×4 and 8×8 massive MIMO antenna configuration radiation patterns are deployed in selected geographical situation for detailed radio network planning using FEKO WinProp platform. Knife edge diffraction, extended walfisch-ikegami and dominant path wave propagation models are implemented with designed MIMO antenna configurations. Modulation schemes of QPSK and QAM with corresponding data rates and throughput for all propagation models are presented. The signal strength and quality reflecting parameters reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and signal to noise plus interference ratio (SNIR) are also evaluated for each model. From the simulation results dominant path model provides data rate and throughput of 3.827, 995 MBit/s and 3.577, 930.1 MBit/s for single stream of data in uplink and downlink respectively. The maximum data rate of 1.37 GBits/s is achieved for deployed base stations with 8×8 massive MIMO antenna configuration effectively covering the entire geographical site.

The present work focus on the development of Cotton fabric with Multi-walled carbon nanotube Coating (CMC) through a dip and dry process. The influence of multi-walled carbon nanotubes (MWCNTs) concentration on transmission, reflection, and absorption properties, which leads to an estimation of electromagnetic interference (EMI) shielding was also studied. The merits of MWCNTs coating on the cotton fabric were evaluated using field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and surface resistivity. The Fourier transform infrared (FTIR) spectroscopy result supports the bonding between MWCNTs and cotton fabric. The significant increase of 98.9% of EMI shielding for the highest MWCNTs weight percentage (22.23 wt%) was attributed due to the well-interconnected network of MWCNTs. The shielding mechanism in the high wt% MWCNTs samples is dominated by both reflection and absorption properties.

This paper presents a slotline open-loop resonators based frequency reconfigurable antenna with autonomous switching of frequency bands. The dual-port slot antenna is designed to operate at 2.1 GHz when excited at port-1, and when port-2 is excited, the antenna can be reconfigured to operate at 2.85 GHz and 5.52 GHz, respectively. Port-1 is used to receive the control signal, which is converted to a DC signal using a rectifier. The rectified control signal is used to switch the operating frequency bands of the port-2. The proposed antenna configuration gives the flexibility of remote/wireless control of the operating frequency. The antenna prototype is fabricated and measured for observing the frequency switching at port-2. The measured results show that the antenna has been effectively switched from lower band frequency (2.8 GHz) to upper band frequency (5.41 GHz) when the PIN diode is ON. The proposed antenna in its final configuration can be potentially suitable for transmitter reconfigurable antenna without the need for external DC bias voltage.

In this paper, a novel dual‐band dual‐polarized leaky‐wave antenna (LWA) with polarization diversity is proposed using half mode substrate‐integrated waveguide (HMSIW)‐based technology. HMSIW LWAs are generally single band. In this work, by etching simple spiral type slots on the HMSIW cavity, a novel dual‐band dual‐polarized LWA is designed. The proposed antenna resonates at 5.6 and 8.5 GHz. Moreover, the antenna radiates the linearly polarized wave in the lower band and circularly polarized (CP) wave in the higher operating band. Also, in the higher operating band between 8.7 and 9.3 GHz, the proposed overall antenna exhibits both right‐hand circular polarization as well as the left‐hand circular polarization in the near main beam direction. The −10 dB impedance bandwidth of the proposed antenna at the lower and the higher operating bands are 27% (4.86‐6.4 GHz) and 25% (7.4‐9.6 GHz), respectively. In the higher band, the 3‐dB axial ratio bandwidth of 6.6% (8.7‐9.3 GHz) is achieved. The main beam of the antenna can be steered from 19° to 69° in the forward direction in the lower operating band. In the higher operating band, the antenna can steer the CP beam between −17° and −32°. In both the lower bands, the realized peak gain is observed around 13.3 dBi, whereas in the higher band, the realized peak gain is observed around 14 dBi.