Varactor diode‐based dual‐band frequency tunable multiple‐input multiple‐output antenna

Author(s):  
Amor Smida ◽  
Amjad Iqbal ◽  
Marwa Selmi ◽  
Ayman A. Althuwayb ◽  
Nazih Khaddaj Mallat
2017 ◽  
Vol 10 (3) ◽  
pp. 383-389
Author(s):  
Deepali Borakhade ◽  
Sanjay Pokle

In this paper, multiple-input–multiple output (MIMO) antenna with dual-band frequency reconfiguration is presented. The proposed antenna consists of two symmetrical pentagon radiating elements. These radiating elements support bands of 1.5 GHz (GPS) and 2.4 GHz (Wi-Fi) frequency. The two PIN diodes are appropriately located on slot line in order to control the current flowing through the radiator. All simulated results are compared and confirmed with measured results. The antenna has VSWR ⩽1.8 and isolation of −28 dB. The advantage of this antenna is that bandwidth is increased by switching of PIN diode in the range from 80 MHz up to maximum 300 MHz. These characteristics demonstrate that proposed antenna is an attractive solution for a multimode application such as GPS, Wi-Fi routers, vehicular communication, etc. where wideband is required.


2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Enze Zhang ◽  
Andrea Michel ◽  
Paolo Nepa ◽  
Jinghui Qiu

A compact, low-profile, two-port dual-band circularly polarized (CP) stacked patch antenna for radio-frequency identification (RFID) multiple-input-multiple-output (MIMO) readers is proposed, which employs the shared-aperture technique. The proposed antenna adopts a 1.524 mm thickness Rogers Ro4350b substrate with relative permittivity of 3.48. Two pairs of isolated ports are working at two microwave- (MW-) RFID bands (2.4–2.485 GHz and 5.725–5.875 GHz) with high port isolation of 25 dB and 30 dB, respectively. A shared metal slot layer is designed to separate two feeding structures of the lower band and upper band for port isolation enhancement as well as saving space. Corner-truncated square slot and patch configurations have been designed to obtain CP modes. In the lower and upper MW-RFID bands, the relative impedance bandwidths are 12.2% and 5.7%, and the maximum realized gains are higher than 7.3 dBic. Moreover, two-element configurations have been combined for an RFID MIMO system that occupies a dimension of 119 mm × 119 mm × 12.9 mm. The MIMO antenna performance of envelope correlation coefficient (ECC) is lower than 0.03, and diversity gain is close to 10 dB.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Abubaker Ahmed Elobied ◽  
Xue-Xia Yang ◽  
Ningjie Xie ◽  
Steven Gao

This paper presents a close-spaced dual-band 2 × 2 multiple-input multiple-output (MIMO) antenna with high isolation based on half-mode substrate integrated waveguide (HMSIW). The dual-band operation of the antenna element is achieved by loading a rectangular patch outside the radiating aperture of an HMSIW cavity. The HMSIW cavity is excited by a coaxial probe, whereas the rectangular patch is energized through proximity coupling by the radiating aperture of HMSIW. The antenna elements can be closely placed using the rotation and orthogonal arrangement for a 2 × 2 array. Small neutralization lines at the center of the MIMO antenna can increase the isolation among its elements by around 10 dB in the lower band and 5 dB in the higher band. A prototype of the MIMO antenna is fabricated and its performance is measured. The measured results show that the resonant frequencies are centered at 4.43 and 5.39 GHz with bandwidths of 110 and 80 MHz and peak gains of 6 and 6.4 dBi, respectively. The minimum isolation in both bands is greater than 35 dB. The envelope correlation coefficient is lower than 0.005 within two operating bands.


Author(s):  
Aziz Dkiouak ◽  
Mohssine El Ouahabi ◽  
Alia Zakriti ◽  
Mohsine Khalladi ◽  
Aicha Mchbal

In this paper, a compact dual band multiple-input multiple-output (MIMO) antenna system for WLAN and X-band satellite applications (2.4/9.8 GHz respectively) is proposed. On the top face of the substrate, two antenna elements with a size of 20 × 24 mm2 are placed side by side and fed with matched orthogonal micro-strip lines. The two antenna elements have orthogonal polarization which can reduce the mutual coupling between its ports. The designed antenna system is fabricated and measured to validate the simulation results. The impedance bandwidths are about 370 MHz (2.19 to 2.56 GHz) and 630 MHz (9.44 to 10.07 GHz), while the obtained isolation is greater than 14 dB at the operating bands. Furthermore, the envelope correlation is less than 0.052 and 0.008 at 2.4 and 9.8 GHz, respectively. Hence the diversity gain is higher than 9.98 in the frequency bands of interest.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Enze Zhang ◽  
Jinghui Qiu

A four-port dual-band dual circularly polarized (CP) stack-up patch antenna is introduced for multiple-input-multiple-output (MIMO) RFID application. The proposed antenna adopts two FR 4 substrates and one Rogers Ro4350b substrates. Two pairs of isolated ports work at FCC UHF/MW-RFID bands (0.902–0.928 and 2.4–2.485 GHz) with port isolations of 20 dB and 25 dB, respectively. Four inverted-F radiating elements fed with a 90° phase-delay feeding network realize the CP radiation at the FCC UHF-RFID band (0.902–0.928 GHz). The corner-truncated square slot and patch are implemented to obtain CP modes at the MW-RFID band. The relative impedance bandwidths in the FCC UHF and MW band are 10.9% and 9.4%, respectively, with peak gains of 4.1 and 7.2 dBic. The antenna’s MIMO performance of envelope correlation coefficient (ECC) is lower than 0.01, and diversity gain (DG) is close to 10 dB. Thanks to the stack-up configuration, the dual-band RFID antenna realizes good antenna performance with a compact size of 0.6 × 0.6 × 0.07 λ3.


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