Yacouba Coulibaly

Hybrid Dielectric Resonator Antenna With Circular Mushroom-Like Structure for Gain Improvement

In this paper, the performance of a cylindrical dielectric resonator antenna (DRA) is improved using a new cylindrical electromagnetic bandgap substrate. The DRA is fed by a coaxial probe and integrated within a cylindrical electromagnetic bandgap (EBG) substrate to increase the antenna gain. The cylindrical electromagnetic bandgap structure is composed of two distinctive periodic structures. The first structure is made of metallic rings, while the second is formed of grounding vias, which are placed radially and circularly. To describe and optimize this EBG stucture, a parametric study using a finite integration method was carried out. Furthermore, an antenna prototype was fabricated and measured to validate the proposed concept. The radiation patterns and return loss obtained from measurements demonstrate a good performance in terms of impedance matching and gain enhancement.

Broadband Microstrip-Fed Dielectric Resonator Antenna for X-Band Applications

A new microstrip fed low profile broadband dielectric resonator antenna is proposed. The antenna is composed of a dielectric resonator, a microstrip fed stepped patch and an intermediate substrate. The stepped patch and the intermediate substrate allow to widen the matching bandwidth. Using a finite integration method (CST Microwave), a parametric investigation was performed for the optimization. To validate the proposed design, a prototype of the optimized antenna was fabricated and measured. The predicted results are compared with the measured data, and a good agreement is achieved. The proposed antenna offers a fractional bandwidth of 50% around the center frequency 10.16 GHz, and relatively stable radiation patterns in the matching band.

Design of a Broadband Hybrid Dielectric Resonator Antenna for X-band Applications

In this paper, a new design of a broadband hybrid antenna for X-band applications is presented. The proposed antenna structure consists of a Dielectric Resonator (DR), an intermediate substrate, and a microstrip fed slot. With the integration of these elements, a wide bandwidth response was achieved. A dual-offset feedline is used to further tune the impedance bandwidth. High Frequency Structure Simulation (HFSS) software package of Ansoft is used to investigate the antenna performance. The input impedance and the far-field patterns were performed out, and a parametric study was done to optimize the antenna performance. The proposed antenna was then fabricated and measured. A good agreement between simulated and measured results was obtained. Experimental results show that the proposed antenna exhibits a wide input impedance bandwidth of 59.1%.

High gain cylindrical dielectric resonator with superstrate for broadband millimeter-wave underground mining communications

This paper presents a new broadband and high gain dielectric resonator for millimeter-wave underground communications systems. The proposed antenna is composed of a superstrate, an aperture coupled feed, an intermediate substrate and a cylindrical dielectric resonator. This antenna is designed to cover the ISM frequency band (57 GHz-65 GHz). This antenna was numerically designed using CST microwave Studio simulation software package. Simulated results show that the antenna has good performances especially in terms of bandwidth and gain. A bandwidth of 18.4% at the centered frequency of 59.83 GHz and a gain of 11 dB over the entire ISM bandwidth have been achieved. An enhancement of gain by 9 dB has been obtained at the frequency of 60 GHz compared to a single DRA. With these performances, this antennas is suitable for wireless underground communication systems.

Design of a high gain hybrid dielectric resonator antenna for millimeter-waves underground applications

This paper presents a new broadband and high gain dielectric resonator antenna for millimeter-wave underground communications systems. The proposed antenna is composed of a microstrip feed, a cylindrical dielectric resonator, and multiple metallic strips stacked to a superstrate. This antenna is dedicated for the 60 GHz frequency band. Results show that the antenna has great performances especially in terms of bandwidth and gain. A bandwidth of 12.69 % at the centered frequency of 59.55 GHz and a gain of 15.40 dBi over the entire band (57 GHz to 64 GHz) are obtained. A maximum gain of 16.71 dBi has been achieved at 58 GHz. This antenna provides an improvement of 10.71 dBi compared to the conventional single DRA. With these performances, this antenna is suitable for wireless underground communication systems.

Wideband Impedance Bandwidth Hybrid Dielectric Resonator Antenna for X-Band Applications

In this paper, a new hybrid resonator is proposed, the proposed design uses three parts, a dielectric resonator (DR), an intermediate substrate and an aperture coupled feed. Furthermore a matching circuit is designed in order to offer a wide bandwidth. The slot aperture is used as a radiator and as a mechanism to couple the DR to the microstrip line. The intermediate substrate is used to isolate the resonator from the slot leading to a structure that is robust to resonator placement and adhesive thickness. It is also used to lower the permittivity of the dielectric resonator antenna (DRA) which increases the bandwidth. Simulation and experimental results including return loss, and radiation patterns are presented and discussed

Design of High Gain and Broadband Antennas at 60 GHz for Underground Communications Systems

A new broadband and high gain dielectric resonator antenna for millimeter wave is presented. The investigated antenna configuration consists of a periodic square ring frequency selective surfaces on a superstrate, an aperture-coupled scheme feed, an intermediate substrate, and a cylindrical dielectric resonator. This antenna is designed to cover the ISM frequency band at 60 GHz (57 GHz–64 GHz). It was numerically designed using CST microwave Studio simulation software package. Another prototype with a plain dielectric superstrate is also studied for comparison purposes. A bandwidth of 13.56% at the centered frequency of 61.34 GHz and a gain of 11 dB over the entire ISM band have been achieved. A maximum gain of 14.26 dB is obtained at 60 GHz. This is an enhancement of 9 dB compared to a single DRA. HFSS is used to validate our antenna designs. Good agreement between the results of the two softwares is obtained. With these performances, these antennas promise to be useful in the design of future wireless underground communication systems operating in the unlicensed 60 GHz frequency band.

A new single layer broadband CPW fed-printed monopole antenna for wireless applications

Broadband antennas have been increasingly investigated in recent years for wireless communication systems. Printed antennas fed by coplanar waveguide can provide a wide bandwidth and can be easily integrated with active circuits. In the same perspective, we proposed a new coplanar fed broadband antenna.. The investigated antenna uses printed monopole with two parasitic elements to widen the bandwidth. The design methodology is outlined. This antenna was numerically designed using Ansoft HFSS simulation software package. A parametric study using an electromagnetic simulator was performed. Based on the optimized design, an experimental prototype was fabricated and measured. Simulations and experimental measurements were carried out, and the comparison between them gives a good agreement. Using this approach, a fractional bandwidth of 47% at the center frequency of 2.35 GHz was achieved. This proposed antenna can be used for broadband wireless communications networks.

High gain rectangular dielectric resonator for broadband millimeter-waves underground communications

This paper presents a new broadband and high gain dielectric resonator for millimeter-wave underground communications systems. The proposed antenna is composed of a superstrate, a coplanar waveguide feed, and a rectangular dielectric resonator. This antenna is designed to cover the ISM frequency band at 60 GHz (57 GHz–65 GHz). This antenna was numerically designed using CST microwave Studio simulation software package. Simulated results show that the antenna has good performances especially in terms of bandwidth and gain. A bandwidth of 17.4% at the centered frequency of 60.98 GHz and a gain of 11 dB over the entire ISM band have been achieved. A maximum gain of 14.44 dB is obtained at 60 GHz. This is an enhancement of 9 dB compared to a single DRA.

Large-scale characterization of an underground mining environment for the 60 GHz frequency band

In order to improve the mining communication applications such as video with high data rates, a characterization of the underground mining channel was done. The use of the IEEE.802.15.3c standard with an OFDM modulation scheme for the 60 GHz can allowobtaining a data rate range from 31.5 Mbps to 5.67 Gbps. This paper provides the propagation characteristics of the mine, which is a complex electromagnetic environment, necessary to the deployment of networks in the IEEE.802.15.3c or the IEEE.802.11ad standard. The experimental results were obtained during an extensive measurement campaign over a frequency range of 61 GHz to 63 GHz in an underground mining environment. These results allow the extracting of the large scale parameters such as the path loss exponent which help to design wireless communication systems. The line of sight (LOS) measurements were performed in the middle of the gallery. Finally, a comparison of the results obtained in a mining environment and in a laboratory is done. The path loss exponents are less than 2 in both scenarios as the environments have dense concentration of scatterers.