With the increase of communication frequency, terahertz (THz) communication technology has been an important research field; particularly the terahertz modulator is becoming one of the core devices in THz communication system. The modulation performance of a THz communication system depends on the characterization of THz modulator. THz modulators based on different principles and materials have been studied and developed. However, they are still on the way to practical application due to low modulation speed, narrow bandwidth, and insufficient modulation depth. Therefore, we review the research progress of THz modulator in recent years and evaluate devices critically and comprehensively. We focus on the working principles such as electric, optical, optoelectrical, thermal, magnetic, programmable metamaterials and nonlinear modulation methods for THz wave with semiconductors, metamaterials, and 2D materials (such as graphene, molybdenum disulfide, and tungsten disulfide). Furthermore, we propose a guiding rule to select appropriate materials and modulation methods for specific applications in THz communication.

/pdf/modulators-for-terahertz-communication-the-current-state-of-4fm7s07jrl.pdf

Modulators for Terahertz Communication: The Current State of the Art.

In this paper the analysis and investigations are carried out on portable antennas for worldwide interoperability for microwave access (WiMAX) applications of flexible coplanar waveguide (CPW)-feed split-triangular shaped patch (STSP). The proposed STSP antenna is fabricated from polyimide substrate material having the dimension of 18×20×0.1 mm3 (volume is 36 mm3). It resonates at 3.55 GHz frequency of a reflection coefficient (S11) of −24.45 dB and offers impedance bandwidth of 580 MHz (3.3–3.88 GHz) with a gain of 2.06 dBi. The STSP antenna has small size, light weight, low volume, and is flexible for WiMAX applications. Simulation and measured results of the proposed STSP antenna are in close agreement.

/pdf/flexible-cpw-fed-split-triangular-shaped-patch-antenna-for-3uqasj7mgx.pdf

Flexible CPW-Fed Split-Triangular Shaped Patch Antenna for WiMAX Applications

The present work was to use photovoltaic solar cells in patch antenna structures. The radiating patch element of a patch antenna was replaced by a solar cell. Direct Current (DC) generation remained the original feature of the solar cell, but additionally   it was now able to receive and transmit electromagnetic waves. Here, we used a new patch antenna structure based on a photovoltaic solar cell. It was then used to collect photo-generated current as well as Radio Frequency (RF) transmission. A mathematical model which would serve the minimization of power losses of the cell and therefore the improvement in the conversion efficiency was studied. A simulation allowed analysing the performance of the antenna, with a silicon material, and testing its parameters such as the reflection coefficient (S11), gain, directivity and radiated power. The performance analysis of the solar cell patch antenna was conducted using Advanced Design System (ADS) software. Simulation results for this antenna showed a dual resonance frequency of 5.77 GHz and of 6.18 GHz with an effective return loss of -38.22dB and a gain of 1.59dBi.

/pdf/patch-antenna-based-on-a-photovoltaic-cell-with-a-dual-4pgm2sj4ir.pdf

Patch Antenna based on a Photovoltaic Cell with a Dual resonance Frequency

A Comprehensive Review of Metamaterials/Metasurface-Based MIMO Antenna Array for 5G Millimeter-Wave Applications

Modeling and validation of a new reconfigurable patch antenna through equivalent lumped circuit-based design for minimum tuning effort

Recently, the RF/microwave electronic technology evolved with the consideration of plastic and organic substrates Such a technology offers two-folded benefits: in one side for lowering the fabrication cost and in another side for the possibility to bend electronic devices Such a technology is particularly interesting for the implementation of antenna system This paper is dealing with the design of flexible microstrip antenna 1:2 array Theoretical approach on the typically symmetrical antenna 1:2 array is proposed The design methodology of microstrip antenna combined with 1:2 T-power divider (T-PWD) is described Based on the transmission line theory, the S-parameter model of the antenna system with non-standard reference load is established Then, the microstrip antenna passive system is theoretical analysed in function of the physical dimensions of the designed structure The feasibility of the flexible antenna passive system is investigated with the proof-of-concept (POC) designed on Kapton substrate The POC prototype consisted of microstrip antenna 1:2 array is designed to operate at about 58 GHz Comparisons between the full wave simulated and measured return losses were performed Then, simulated radiation pattern highlights the efficiency of the fabricated prototype of passive antenna array

https://www.jpier.org/pierc/pierc63/11.15120906.pdf

Design of Flexible Passive Antenna Array on Kapton Substrate

This paper proposes an empirical analysis of the thermal influence on the electrical behavior of a flexible passive patch antenna which is printed on a Kapton-based substrate. The measurement protocol along with the use of the thermal chamber enabling the temperature control is presented. The experimental setup for measuring the input reflection coefficient with temperature variation ranging from 25°C to 150°C is described. Then, the input impedance of the tested microstrip circuit is analyzed given the quality factor and the antenna bandwidth. It is seen that, increasing the temperature decreases the quality factor of the antenna which is also noticeable through the matching level of the reflection coefficient. This is mainly explained by the drop of the conductivity of the top conductor made by silver ink-jet printing.

Y. G. Rabobason

Papers

Design of Flexible Passive Antenna Array on Kapton Substrate

Thermal empirical effect on the Kapton-based passive microstrip circuit