Mohsen Khalily

Frequency-Reconfigurable Rectangular Dielectric Resonator Antenna

A coplanar waveguide (CPW) reconfigurable dielectric resonator antenna (DRA) is presented and investigated. The DRA is capable of frequency tuning at three different frequency bands between 3.45 and 6.77 GHz. The overall size of the antenna is 50 × 57 mm2. The dielectric material is a rectangular block of ceramic with a permittivity of 15. Two switches, implemented using p-i-n diodes, are located on the lines of a feed network that is connected to the dielectric element. Single-band modes with impedance bandwidths of 8% and 16% are achieved by switching “on” one of three connecting feedline networks, whereas a wide band, with an impedance bandwidth of 65%, is achieved by switching “on” two connecting lines. Frequencies in the single band can be independently controlled using switch positions without affecting the wideband mode. The prototype has a low profile with a dielectric resonator thickness of 4 mm. The characteristics of this antenna were studied, and good agreement was found between the numerical and measured results.

Design of an MIMO Dielectric Resonator Antenna for 4G Applications

AbstractnA two-port MIMO Dielectric Resonator Antenna (DRA) has been proposed and studied. The antenna consists of a single Rectangular DRA (RDRA) element housed in a thin FR4 substrate, that is fed by two microstrip feed lines. Both the feeding lines excite

Rectangular Dielectric Resonator Antenna Array for 28 GHz Applications

{text{TE}}_{updelta 11}^{text{X}}

Indoor wideband directional millimeter wave channel measurements and analysis at 26 GHz, 32 GHz, and 39 GHz: Indoor wideband directional millimeter wave channel measurements and analysis at 26 GHz, 32 GHz, and 39 GHz

TEδ11X mode in the RDRA. The mutual coupling between the ports has been decreased by employing two symmetrical slits in the ground plane. The proposed antenna has been fabricated and a parametric study has been carried out to obtain the optimum parameters. The presented antenna with acceptable MIMO characteristics, covers a measured bandwidth of 80xa0MHz (2.56–2.64xa0GHz) for |S11|xa0<xa0−10xa0dB, which is able to operate on LTE band 38. The measured isolation between the two ports for the desired frequency band is better than 20xa0dB. The presented antenna has been examined by calculating and measuring the Envelope Correlation Coefficient, Mean Effective Gains and the Diversity Gain. Based on the study that has been carried out, the antenna offers easy fabrication, feeding and good MIMO characteristics. Therefore, the presented antenna can be a suitable candidate for LTE applications.

Steerable Higher Order Mode Dielectric Resonator Antenna With Parasitic Elements for 5G Applications

New modified 2 × 2 and 3 × 3 series-fed patch antenna arrays with beam-steering capability are designed and fabricated for 28-GHz millimeter-wave applications. In the designs, the patches are connected to each other continuously and in symmetric 2-D format using the high-impedance microstrip lines. In the first design, 3-D beam-scanning range of ± 25° and good radiation and impedance characteristics were attained by using only one phase shifter. In the second one, a new mechanism is introduced to reduce the number of the feed ports and the related phase shifters (from default number 2 N to the reduced number N + 1 in the serial feed (here N = 3) and then the cost, complexity, and size of the design. Here, good scanning performance of a range of ± 20°, acceptable sidelobe level, and gain of 15.6 dB are obtained. These features allow to use additional integrated circuits to improve the gain and performance. A comparison to the conventional array without modification is done. The measured and simulated results and discussions are presented.

A Novel Equivalent Definition of Modified Bessel Functions for Performance Analysis of Multi-Hop Wireless Communication Systems

In this paper, a Rectangular Dielectric Resonator Antenna (RDRA) with a modified feeding line is designed and investigated at 28 GHz. The modified feed line is designed to excite the DR with relative permittivity of 10 which contributes to a wide bandwidth operation. The proposed single RDRA has been fabricated and mounted on a RT/Duroid 5880 (er = 2.2 and tanδ = 0.0009) substrate. The optimized single element has been applied to array structure to improve the gain and achieve the required gain performance. The radiation pattern, impedance bandwidth and gain are simulated and measured accordingly. The number of elements and element spacing are studied for an optimum performance. The proposed antenna obtains a reflection coefficient response from 27.0 GHz to 29.1 GHz which cover the desired frequency band. This makes the proposed antenna achieve 2.1 GHz impedance bandwidth and gain of 12.1 dB. Thus, it has potential for millimeter wave and 5G applications.

Switched parasitic dielectric resonator antenna array using capacitor loading for 5G Applications

This paper proposes a low-complexity hybrid beamforming design for multi-antenna communication systems. The hybrid beamformer is comprised of a baseband digital beamformer and a constant modulus analog beamformer in the radio frequency (RF) part of the system. As in singular-value-decomposition (SVD)-based beamforming, hybrid beamforming design aims to generate parallel data streams in multi-antenna systems, however, due to the constant modulus constraint of the analog beamformer, the problem cannot be solved similarly. To address this problem, mathematical expressions of the parallel data streams are derived in this paper and desired and interfering signals are specified per stream. The analog beamformers are designed by maximizing the power of desired signal while minimizing the sum-power of interfering signals. Finally, digital beamformers are derived by defining the equivalent channel observed by the transmitter/receiver. Regardless of the number of the antennas or type of channel, the proposed approach can be applied to a wide range of MIMO systems with hybrid structure wherein the number of the antennas is more than the number of the RF chains. In particular, the proposed algorithm is verified for sparse channels that emulate mm-wave transmission as well as rich scattering environments. In order to validate the optimality, the results are compared with those of the state-of-the-art and it is demonstrated that the performance of the proposed method outperforms state-of-the-art techniques, regardless of type of the channel and/or system configuration.

Sidelobe reduction of unequally spaced arrays for 5G applications

This paper presents details of the wideband directional propagation nmeasurements of millimetre-wave (mmWave) channels nin the 26 GHz, 32 GHz, and 39 GHz frequency bands nin an indoor typical office environment. More than 14400 npower delay profiles (PDPs) were measured across the 26 nGHz band and over 9000 PDPs have been recorded for the n32 GHz and 39 GHz bands at each measurement point. A nmmWave wideband channel sounder has been used, where nsignal analyzer and vector signal generator was employed. nMeasurements have been conducted for both co- and crossantenna npolarization. The setup provided 2GHz bandwidth nand the mechanically steerable directional horn antenna with n8 degrees beamwidth provides 8 degrees of directional resolution nover the azimuth for 32 GHz and 39 GHz while 26 nGHz measurement setup provides the angular resolution of n5 degrees. Measurements provide path loss, delay and spatial nspread of the channel. Large-scale fading characteristics, nRMS delay spread, RMS angular spread, angular and ndelay dispersion are presented for three mmWave bands nfor the line-of-sight (LoS) scenario.