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Miniaturized Frequency Reconfigurable Pentagonal MIMO Slot Antenna for Interweave CR Applications

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Miniaturized Frequency Reconfigurable Pentagonal MIMO Slot Antenna for Interweave CR Applications Miniaturized frequency reconfigurable pentagonal MIMO slot antenna for interweave CR applications Item Type Article Authors Hussain, Rifaqat; Raza, Ali; Khan, Muhammad U.; Shamim, Atif; Sharawi, Mohammad S. Citation Hussain R, Raza A, Khan MU, Shammim A, Sharawi MS (2019) Miniaturized frequency reconfigurable pentagonal MIMO slot antenna for interweave CR applications. International Journal of RF and Microwave Computer-Aided Engineering: e21811. Available: http://dx.doi.org/10.1002/mmce.21811. DOI 10.1002/mmce.21811 Publisher Wiley Journal International Journal of RF and Microwave Computer-Aided Engineering Download date 01/10/2021 07:53:51 Link to Item http://hdl.handle.net/10754/653090 Pentagonal Slot MIMO Reconfigurable Antenna 1 Miniaturized Frequency Reconfigurable Pentagonal MIMO Slot Antenna for Interweave CR Applications Rifaqat Hussain 1, Ali Raza 2, Muhammad U. Khan 3, Atif Shammim 4 and Mohammad S. Sharawi 5 1 Electrical Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia, Email: [email protected]. 2 Department of Electrical Engineering, University of Engineering and Technology Lahore, Faisalabad Campus, Pakistan 3 Research Institute for Microwave and Millimeter-Wave Studies, National University of Science and Technology, Islamabad, 44000, Pakistan 4 Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University (KAUST) of Science and Technology, Thuwal 23955-6900, Saudi Arabia 5 Electrical Engineering Department, Polytechnique Montr´eal, Montreal, QC H3T 1J4, Canada, Email: [email protected] ABSTRACT: In this paper, a miniaturized 4-element frequency reconfigurable multiple- input-multiple-output (MIMO) antenna system is presented. The proposed design is low profile with planar configuration. The design consists of pentagonal slot-based frequency reconfigurable antenna elements. Varactor diodes are used to change the capacitive reactance of the slot. The MIMO antenna system can be tuned over a frequency band covering 3.2 - 3.9 GHz with at least 100 MHz bandwidth within each band. The proposed antenna covers several commercial standards including WiMAX (3.4-3.6 GHz), TDD LTE (3.6-3.8 GHz) and Wi-Fi 802.11y (3.65-3.7 GHz), along with several other bands. The proposed design was realized on a board of dimensions 60×120 mm 2. The isolation between adjacent antenna elements is improved using slot-line based defected ground structures (DGS). The antenna maintains a minimum isolation of 10 dB in its entire covered operating bands. The antenna is also analyzed for its far-field characteristics and MIMO performance parameters. The proposed design is suitable to be used in mobile handsets for cognitive radio (CR) platforms. Keywords: pentagonal slot, MIMO, frequency reconfigurable, WiMAX 1 INTRODUCTION In modern wireless communication systems, there is continuous demand to have high system throughput. New features and services are continuously added to wireless handheld devices which require operation across various frequency standards. The increase in the number of users of such services might result in frequency spectrum congestion. Meeting the high data rate requirements with multiple wireless standards operation and efficient utilization of spectrum resources can be accomplished by utilizing frequency reconfigurable multiple-input-multiple-output (MIMO) antenna systems in cognitive radio (CR) platforms. CRs are being developed to effectively utilize spectrum resources. Frequency reconfigurable MIMO antennas are an integral part of CR front-ends which can change their operating band as per user requirements to avoid spectrum congestion. CR techniques were developed to utilize the spectrum resources more efficiently in [1]-[2]. A CR senses the radio frequency (RF) spectrum using an ultra-wide-band (UWB) sensing antenna, finds a spectrum hole and allocates the available spectrum to the secondary user to use it for communication. To interact dynamically with RF spectrum and provide efficient channel allocation requires an adaptive RF front-end. Thus, a CR front-end needs a frequency reconfigurable antenna or a reconfigurable MIMO antenna system, which can change the resonance frequency as per user requirements and hence improve spectrum utilization. A number of different types of antennas (PIFA, loop and monopole) were presented for CR applications, however slot-based pentagonal reconfigurable antennas are potentially good candidates because of their planar structure, low profile and ease of integration with other circuit components on a single printed circuit board (PCB). Several frequency reconfigurable antennas were reported in literature such as [3]-[7]. In [3], a frequency reconfigurable antenna was presented based on transistor switching. The antenna covered 3 different bands: WLAN (2.4-2.48 GHz), WiMAX (2.5-2.69 GHz, 3.4-3.69 GHz) and PCS (1.85-1.99 GHz) with substrate dimensions of 30×30×1.524 mm 3. In [4], a PIN diode based frequency agile antenna was presented for Bluetooth, WiMAX, and WLAN applications. The antenna covered 2.2-2.53 GHz, 2.97-3.71 GHz and 4.51-6 GHz bands with a substrate area of 45×50 mm 2. In [5], PIN diode based frequency reconfigurable microstrip square slot antenna was presented with antenna dimensions 20×20×0.8 mm 3. The frequency agile antenna covered the frequency bands 2.3-2.51 GHz, 3.35-3.75 GHz, and 4.95-5.53 GHz for Bluetooth, WiMAX and WLAN, respectively. In [6], a planar frequency reconfigurable antenna was presented covering the bands 1.6-6.0 GHz and 3.39-3.80 GHz. The dimensions of the substrate used were 120×103 mm 2. A PIN diode controlled band-pass structure was integrated with the antenna to make it frequency reconfigurable. In [7], a compact frequency reconfigurable slot antenna was presented. The bands covered by the antenna were 2.3 GHz, 4.5 GHz and WLAN 5.8 GHz with total substrate size of 27×25×0.8 mm 3. PIN diodes were integrated inside the slots to switch the resonance frequency of the antenna between single-band mode (LTE and WLAN) and two-band mode (LTE, AMT fixed service and WLAN). MIMO antennas are commonly used to meet the high data rate requirements in current wireless systems. MIMO frequency reconfigurable antennas are highly desirable in CR applications. Some of the relevant MIMO antennas to the proposed design were presented in [8]-[12]. In [8], a 2-element frequency reconfigurable MIMO antenna was presented with substrate area of 90×50 mm 2. The antenna covered three Pentagonal Slot MIMO Reconfigurable Antenna 3 m-WiMAX bands 2.3-2.4 GHz, 2.5-2.7 GHz and 3.4-3.6 GHz. PIN diodes were used to achieve frequency reconfigurability. A 2-element MIMO patch antenna was presented in [9]. A varactor diode based frequency agile antenna was tuned over the bands 2.12-2.32 GHz with substrate area of 100×50 mm 2. In [10], a 2- element frequency reconfigurable monopole MIMO antenna was presented. The antenna covered WLAN (2.4-2.483 GHz and 5.15-5.35 GHz) and WiMAX (3.4-3.6 GHz) bands. In [11], a 2-element PIN diode based frequency reconfigurable monopole MIMO antenna was presented. The antenna was tuned over the bands 1.88-2.64 GHz with substrate dimensions of 49×55 mm 2. In [12], a 2-element MIMO frequency agile antenna was presented with total substrate size of 48.5×25 mm 2. The bands covered were WiMAX (3.36- 3.7 GHz), WLAN (5-5.8 GHz) and WiMAX and WLAN (3.17-3.77 GHz and 5.13-5.88 GHz). 4-element based MIMO antennas were presented in [13]-[17]. In [13], [14], the 4-element modified monopole based frequency agile meandered F-shaped MIMO antenna was tuned over various frequency bands between 0.7-3 GHz with total substrate dimensions of 65×120×1.56 mm 3. Both PIN and varactor diodes were used to get the reconfigurability function. In [17], a compact 4-element frequency reconfigurable antenna was presented. Reconfigurability was achieved using MEMS switches. The antenna covered the bands 4.9-5.725 GHz, 2.4-2.5 GHz and 4.9-5.725 GHz. The board dimensions were 46×20×1.6 mm 3. Some state of the art tunable technique are reported in [18]-[19]. In [18], a technique based on tunable meta-atoms with reverse bias varactor diodes resolve the issues of microwave metasurfaces. The dispersive response of each meta-atom is precisely controlled by an external voltage applied to the diode. In [19], a tunable metasurface is integrated with diodes as active elements can be utilized to control the reflection phase of EM waves. The switching of the two distinct states of the devices was successfully demonstrated by applying different voltage across the diode terminals. Similarly, metamaterial based low coupling techniques are cited in [20]-[21. In [20], a significant reduction in mutual coupling was obtained using the magnetic waveguide metamaterial (MTM). The concept was implemented on a microstrip antenna of 5×1 array. Simulated and measured results showed a mutual coupling reduction of more than 9.7 dB in the entire band of operation. In [21], two complementary spiral ring resonators (CSRs) with two and three concentric rings were arranged optimally to reduce the mutual coupling more than 8.4dB between two H- plane coupled patch antennas. In this paper, a pentagonal slot-based miniaturized frequency reconfigurable MIMO antenna is presented. The design consists of 4 antenna elements that are etched out of the ground (GND). The proposed antenna provides a continuous frequency sweep over the bands 3.2 to 3.9 GHz with minimum -10 dB operating bandwidth of 55 MHz (100 MHz when considering the -6 dB bandwidth). The proposed antenna covers several standards including WiMAX (3.4-3.6 GHz) band, TDD LTE (3.6-3.8 GHz) and Wi-Fi 802.11y (3.65-3.7 GHz), LTE bands 42 (3.4-3.6 GHz), 43 (3.6-3.8 GHz), along with several others.
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