Imran Shoaib

This paper presents a compact coaxial-fed square microstrip patch antenna integrated with a beam-steering Partially Reflective Surface (PRS). The proposed design has a two-dimensional (2-D) Fabry-Perot Cavity (FPC) antenna acting as a radiator and the PRS as a beam-steering superstrate operating at 5.5 GHz. The PRS consists of 6 × 6 reconfigurable unit cells etched on Rogers 5880 with a thickness of 1.57 mm. By controlling the switching of PIN diodes in different sections of PRS, beam steering can be achieved up to ±47° in the azimuth plane with a gain of 9.1 dB and 10.2 dB and ± 15° steering in an elevation plane with a measured gain of 9.3 dB and 8.9 dB, respectively. The antenna prototype is 2.56 λ × 2.56 λ at 5.5 GHz, and the measured gain values are around 10 dBi for all the states. The beam is able to radiate at boresight or tilted to 42° in two azimuthal directions and 45° in elevation direction by adjusting the PIN diodes ON/OFF states. The 10 dB impedance bandwidth of 5.4–5.52 GHz is achieved.

This paper presents the design of $8 \times 8$ multiple-input multiple-output (MIMO) antennas for future 5G devices, such as smart watches and dongles. Each antenna of the MIMO configuration occupies $3 \times 4$ mm ² and is printed on the top layer of the substrate in the form of a rotated H-shaped patch. The substrate used for the design is a $31.2 \times 31.2 \times 1.57$ mm ³ , Rogers RT-5880 board, with a dielectric constant of 2.2. The top layer of the substrate has eight MIMO antennas, whereas the bottom layer is composed of ground plane. The ground plane is an electromagnetic bandgap-based structure designed for the enhancement of gain and efficiency. Each antenna is fed from the bottom layer of the substrate through vias to avoid any spurious radiation. The MIMO antennas resonate at 25.2 GHz with a 6-dB percentage bandwidth of 15.6%. The gain attained by the antennas in the entire bandwidth is above 7.2 dB with a maximum value of 8.732 dB at the resonant frequency. Likewise, the value of efficiency attained by the antennas in the entire bandwidth is above 65% with a maximum value of 92.7% at the resonant frequency. The simulation and measurement results have substantiated a good performance of the MIMO antennas, thus making them suitable for compact 5G devices.

This paper presents compact pattern reconfigurable antennas for mobile handsets in MIMO configuration. Each antenna of the MIMO configuration being coupled fed monopole in meandered form is capable of covering several cellular frequency bands in the range of 1.75–2.67 GHz including 4G‐LTE, 2G‐GSM, 3G‐UMTS, and WLAN. The MIMO antennas are printed diagonally at the left and right no‐ground portions on the top layer of the substrate to enhance the isolation performance. The substrate used is FR‐4 with relative permittivity of 4.35 and loss tangent of 0.02. The volume of the substrate is 120 × 65 × 1.6 mm³ with each antenna occupying an area of 26.5 × 14.5 mm². The pattern reconfigurability is achieved by connecting and disconnecting a 4.5 × 2 mm² metallic strip using the p‐i‐n diode switch. The antennas are pattern reconfigurable in the frequency range of 1.9–2.1 GHz. The isolation achieved is better than 16 dB over all the frequency bands covered by each antenna. A prototype has been fabricated and tested. The simulated and measured results show a good performance of the MIMO antennas. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:148–156, 2017

This paper presents two MIMO antennas for 2G, 3G and 4G cellular handsets. Each antenna is meandered to form a loop structure for achieving resonance at 0.25λ and 0.5λ. The substrate used for the design is FR-4 with relative permittivity of 4.35 and loss tangent of 0.02. The overall size of the substrate is 70 × 107.5 × 0.8 mm3 with each antenna occupying an area of 50 × 10 mm2. The decoupling structure on the bottom layer of the substrate is composed of two slots etched horizontally in the ground plane. The antennas are capable of covering 2G GSM 850 (824 - 894 MHz), 2G GSM 1900 (1850 - 1990 MHz), 3G HSDPA 800 (800 - 890 MHz), 3G HSDPA 850 (814 - 894 MHz), 3G HSDPA 2100 (1920 - 2170 MHz), 4G LTE bands 1-2, 7, 30 (1920 - 2690 MHz), 4G LTE bands 5, 12-13, 17-20, 26, 28 (680 - 912 MHz), WLAN 802.11 a/b/g/n (2400 - 2480 MHz) and WLAN 802.11h (3400 - 3600 MHz). The isolation achieved between antennas is better than 12 dB in the lower and 18 dB in the upper frequency bands.

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.

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 mm ³ . Each antenna covers an area of approximately 75 × 50 mm ² . 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.

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 mm ³ . 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.

This letter presents a pair of printed MIMO antennas for mobile handsets. With each antenna being a coupled fed monopole in a meandered shape, it is capable of covering GSM 1800/1900, UMTS, WLAN, and LTE frequency bands. The antennas are oriented diagonally at the nongrounded portion of the circuit board. The substrate used for the circuit board is FR4 with relative permittivity of 4.4 and loss tangent of 0.02. The overall volume of the circuit board is 110×65×0.8 mm ³ , with each antenna occupying an area of 24×14.5 mm ² . To improve the isolation between antennas, dual decoupling structures consisting of ground slots and inverted L ground branches that extend into the nongrounded portion are etched diagonally on the bottom layer of the substrate. The isolation achieved is better than 15 dB over all the frequency bands covered by each antenna leading to an envelope correlation coefficient of less than 0.02. The simulation and measured results are in good agreement.

A low profile and compact printed pattern reconfigurable antenna for mobile handsets is presented in this paper. The antenna is capable of covering GSM 1800(1710-1880 MHz), GSM 1900(1850-1990 MHz), UMTS (1920-2170 MHz), WLAN (2400-2480 MHz) and LTE frequency bands in the range of 1.7-2.7 GHz when referenced to a return loss of 6dB. The antenna is composed of a coupled fed meandered monopole antenna with an extended metallic branch for pattern re-configurability. The extended metallic branch is connected and disconnected by using the p-i-n diode switch which changes the path for current flow thereby achieving pattern re-configurability. When the p-i-n diode is `ON', the metallic branch is activated and the current start flowing through it and pattern is shifted to the left. When the p-i-n diode is in `OFF' state, the metallic branch is disconnected and the pattern is shifted to the right. The substrate used for the circuit board is FR-4 with the relative permittivity of 4.35, loss tangent of 0.02 and a volume of 65 × 110 × 0.8 mm ³ . The antenna inhabits an area of 24 × 14.5 mm ² . The simulation and measurement results corroborate a good performance of the antenna.

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.