Imran Shoaib

Design and Performance Study of a Dual-Element Multiband Printed Monopole Antenna Array for MIMO Terminals

This letter presents a study on linearly polarized compact multiband multiple-input-multiple-output (MIMO) antenna system for small mobile terminals. The MIMO antenna system consists of two symmetric printed monopole antennas with edge-to-edge separation of 0.097 λ0 at 900 MHz. Each antenna element has a capacitive feed and is composed of two twisted lines, a parasitic loop, and a shorting trip that generate five resonant modes around 900, 1800, 2100, 3500, and 5400 MHz, covering GSM850/900, DCS, PCS, UMTS, WLAN, and WiMAX frequency bands. Two inverted-L shaped branches and a rectangular slot with one circular end, etched on the ground plane, were introduced to improve the isolation between antenna elements. The isolation achieved is higher than 15 dB in the lower band and 20 dB in the upper bands, leading to an envelope correlation coefficient of less than 0.025. The simulated performance of the designed antenna system has been verified in the experiment.

MIMO Antennas for Mobile Handsets

In this paper, two multiband MIMO antennas for mobile handsets are proposed. The first antenna is capable of covering GSM900, GSM1800, GSM1900, and UMTS. It has two loop type antenna elements, which are with the same structures and dimensions. The dimensions of the antenna element is 22.5*25mm2. Two structures which are slot and inverted-L branches on the ground, are used to minimize the mature coupling between the two antenna elements. The second antenna can cover GSM1800, GSM1900, UMTS, WLAN and LTE frequency bands. The presented antenna consist of two coupled fed monopole antennas that are oriented diagonally at the non-grounded portion of the circuit board. Two decoupling structures are etched diagonally on the bottom layer of the circuit board to improve the isolation between the two antenna elements. Both of simulation and measurement results are shown to illustrate the performance of the proposed two MIMO antennas.

Compact UWB-MIMO antenna array with a novel decoupling structure

In this paper, a compact planar Ultra-Wideband (UWB) Multiple-input Multiple-output (MIMO) antenna array is proposed. This UWB-MIMO antenna array consists of two identical monopole antenna elements with a novel decoupling structure etched on the ground plane. The antenna performs very well over the UWB frequency range of 3.1-10.6 GHz. The decoupling structure improves the isolation between the antennas over the complete frequency band which can only be achieved otherwise by increasing the separation between the antenna elements. The analysis of antenna performance with and without stub is provided to demonstrate the significance of adding the decoupling stub to the design. The proposed compact and cost efficient antenna array system measures 27 × 47 mm2 only.

Pattern-Reconfigurable Dual-Polarized Dielectric Resonator Antenna

We present a portable pattern-reconfigurable dual-polarized dielectric resonator antenna (DRA). Low-cost gallium arsenide (GaAs) single-pole, double-throw (SPDT) switches are utilized to select one of the feedline paths of the DRA, giving a boresight or cardioid pattern electronically. The measured results verify the proposed antenna switches its radiation patterns between cardioid and boresight shape, without significantly affecting its matching in the operating frequency range of 5-6 GHz. Results also confirm that the pattern configuration in one port with one polarization does not affect the RF characteristics of the other port with alternative polarization of the antenna. This two-port configuration makes the proposed antenna a suitable candidate for IEEE 802.11ac multi-user multiple-input-multiple-output (MU-MIMO) applications.

Compact and printed MIMO antennas for 2G/3G and 4G — LTE mobile tablets

This paper presents four meandered MIMO antennas printed in symmetric configuration on top and bottom no-ground edges of the substrate. Two of the four MIMO antennas are coupled fed monopoles covering GSM 900/GSM 1800/1900, UMTS and WLAN frequencies whereas, the other two MIMO antennas are direct fed monopoles covering LTE 700 and WLAN 2.45 GHz. The substrate used is FR-4 with relative permittivity of 4.35 and an overall volume of 230 × 176 × 0.8 mm3. Each antenna covers an area of approximately 75 × 50 mm2. The decoupling technique used in the design involves four ground slots and two coupled ground extensions. The isolation performance of the MIMO antennas is better than 15 dB over all the cellular bands covered by the antennas. The simulated and measured results substantiate a good performance of the MIMO antennas.

Compact and printed multiband antennas for 2G/3G/4G smartphones

This paper presents a compact multiband antenna system for mobile handsets capable of covering 2G, 3G and 4G cellular frequency bands. The antenna system is composed of two antennas that are etched diagonally on the non-grounded portion of the substrate board. The substrate board used is FR-4, of relative permittivity 4.35 and loss tangent of 0.02, with overall dimensions of 136 × 70 × 0.8 mm3. The antenna for covering 4G and WLAN frequency bands is a direct fed printed monopole antenna whereas, the antenna for covering the 2G and 3G cellular services is a coupled fed monopole antenna. Two inverted-L shaped metallic extensions, etched on the bottom layer of the substrate, were introduced to improve the isolation between antennas. The isolation achieved is better than 16 dB in the lower band and 22 dB in the upper bands, leading to an envelope correlation coefficient of less than 0.251. The simulated and measured results corroborate a good performance of the proposed antenna system.

Optically tuned polarisation reconfigurable antenna

A polarisation reconfigurable circular polarised (CP) antenna for GPS application is designed and built using four photoconductive switches. By controlling the ON/OFF state of each of the four photoconductive switches on patch antenna, the polarisation of antenna can be switched from linear (LP) to CP, and from left hand CP (LHCP) to right hand CP (RHCP).

A pattern reconfigurable dielectric resonator antenna array for adaptive MIMO systems

This paper presents our latest study on the design of reconfigurable antennas and the performance achievable by employing such antennas in multiple-input multiple-output (MIMO) systems. The proposed antenna system consists of two identical dielectric resonator antennas (DRA) placed on a horizontal ground plane and separated by a distance of 0.2}i at design frequency of 2.45 GHz. Each element has three different radiation modes: TEx mode, TEy mode and a monopole mode. By switching between these modes, the induced current distribution on DRA can be changed, resulting in different radiation patterns, which can achieve pattern reconfiguration to increase channel capacity in varying channel conditions. The performance with such reconfigurable antennas in a 2×2 MIMO system is evaluated using ray-tracing simulations in an indoor environment.

Pattern reconfigurable planar UWB antenna array for future cognitive radio portable devices

A novel pattern reconfigurable planar ultra wideband 2×2 antenna array is presented. This UWB planar array has a high gain that can be useful in sensing the spectrum for cognitive radio applications. The array can provide basic pattern reconfiguration to enhance the scanning and the communication performance in cognitive radio operation by limiting interference coming from specific directions. The reflection coefficient, radiation patterns, gain and total efficiency simulations of the UWB mode and the reconfiguration modes are presented. The pattern reconfigurablity of the proposed antenna is also investigated by simulating indoor coverage and power received in a realistic environment for different pattern configurations.

A pattern reconfigurable DRA array for MIMO applications

This paper presents our study on the dielectric resonator antennas (DRA) to achieve pattern reconfigurability. The antenna array consists of two identical DRA placed at the center of two perpendicular planes. The antenna demonstrates radiation pattern reconfiguration in the 2.4 GHz frequency spectrum and therefore improves the channel capacity of a MIMO communication system. With 3 antenna modes in each DRA, the MIMO system can automatically select within 9 different pattern combinations to achieve optimum channel capacity at different receiver locations.