Investigaciones financiadas por la Unión Europea (OpenAire) - Europar Batasunak finantzatutako ikerketak (OpenAire)

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Open Access
Analysis of gyrobianisotropic media effect on the input impedance, field distribution and mutual coupling of a printed dipole antenna
(Springer Nature, 2022) Bouknia, Mohamed Lamine; Zebiri, Chemseddine; Sayad, Djamel; Elfergani, Issa; Matin, Mohammad; Alibakhshikenari, Mohammad; Alharbi, Abdullah G.; Hu, Yim Fun; Abd-Alhameed, Raed; Rodriguez, Jonathan; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
In this paper, we present an analytical study for the investigation of the effects of the magnetoelectric elements of a reciprocal and nonreciprocal bianisotropic grounded substrate on the input impedance, resonant length of a dipole antenna as well as on the mutual coupling between two element printed dipole array in three configuration geometries: broadside, collinear and echelon printed on the same material. This study examines also the effect of the considered bianisotropic medium on the electric and magnetic field distributions that has been less addressed in the literature for antenna structures. Computations are based on the numerical resolution, using the spectral method of moments, of the integral equation developed through the mathematical derivation of the appropriate spectral Green's functions of the studied dipole configuration. Original results, for chiral, achiral, Tellegen and general bi-anisotropic media cases, are obtained and discussed with the electric and magnetic field distributions for a better understanding and interpretation. These interesting results can serve as a stepping stone for further works to attract more attention to the reciprocal and non-reciprocal Tellgen media in-depth studies. © 2022, The Author(s).
Open Access
Antenna mutual coupling suppression over wideband using embedded periphery slot for antenna arrays
(MDPI, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; Shukla, Panchamkumar; See, Chan H.; Abd-Alhameed, Raed; Khalily, Mohsen; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a new approach to suppress interference between neighbouring radiating elements resulting from surface wave currents. The proposed technique will enable the realization of low-profile implementation of highly dense antenna configuration necessary in SAR and MIMO communication systems. Unlike other conventional techniques of mutual coupling suppression where a decoupling slab is located between the radiating antennas the proposed technique is simpler and only requires embedding linear slots near the periphery of the patch. Attributes of this technique are (i) significant improvement in the maximum isolation between the adjacent antennas by 26.7 dB in X-band and >15 dB in Ku and K-bands; (ii) reduction in edge-to-edge gap between antennas to 10 mm (0.37 ); and (iii) improvement in gain by >40% over certain angular directions, which varies between 4.5 dBi and 8.2 dBi. The proposed technique is simple to implement at low cost.
Open Access
Automated reconfigurable antenna impedance for optimum power transfer
(IEEE, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents an approach to implement an automatically tuning antenna for optimising power transfer suitable for software defined radio (SDR). Automatic tuning is accomplished using a closed loop impedance tuning network comprising of an impedance sensor and control unit. The sensor provides the control unit with data on the transmit or receive power, and the algorithm is used to impedance of a T-network of LC components to optimize the antenna impedance to maximise power transmission or reception. The effectiveness of the proposed tuning algorithm in relation to impedance matching and convergence on the optimum matching network goal is shown to be superior compared with the conventional tuning algorithm.
Open Access
A comprehensive survey on "Various decoupling mechanisms with focus on metamaterial and metasurface principles applicable to SAR and MIMO antenna systems"
(IEEE, 2020) Alibakhshikenari, Mohammad; Babaeian, Fatemeh; Virdee, Bal S.; Aïssa, Sonia; Azpilicueta Fernández de las Heras, Leyre; See, Chan H.; Falcone Lanas, Francisco; Althuwayb, Ayman Abdulhadi; Huynen, Isabelle; Abd-Alhameed, Raed; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Nowadays synthetic aperture radar (SAR) and multiple-input-multiple-output (MIMO) antenna systems with the capability to radiate waves in more than one pattern and polarization are playing a key role in modern telecommunication and radar systems. This is possible with the use of antenna arrays as they offer advantages of high gain and beamforming capability, which can be utilized for controlling radiation pattern for electromagnetic (EM) interference immunity in wireless systems. However, with the growing demand for compact array antennas, the physical footprint of the arrays needs to be smaller and the consequent of this is severe degradation in the performance of the array resulting from strong mutual-coupling and crosstalk effects between adjacent radiating elements. This review presents a detailed systematic and theoretical study of various mutual-coupling suppression (decoupling) techniques with a strong focus on metamaterial (MTM) and metasurface (MTS) approaches. While the performance of systems employing antenna arrays can be enhanced by calibrating out the interferences digitally, however it is more ef cient to apply decoupling techniques at the antenna itself. Previously various simple and cost-effective approaches have been demonstrated to effectively suppress unwanted mutual-coupling in arrays. Such techniques include the use of defected ground structure (DGS), parasitic or slot element, dielectric resonator antenna (DRA), complementary split-ring resonators (CSRR), decoupling networks, P.I.N or varactor diodes, electromagnetic bandgap (EBG) structures, etc. In this review, it is shown that the mutual-coupling reduction methods inspired by MTM and MTS concepts can provide a higher level of isolation between neighbouring radiating elements using easily realizable and cost-effective decoupling con gurations that have negligible consequence on the array's characteristics such as bandwidth, gain and radiation ef ciency, and physical footprint.
Open Access
Double-port slotted-antenna with multiple miniaturized radiators for wideband wireless communication systems and portable devices
(Electromagnetics Academy, 2019) Alibakhshikenari, Mohammad; Khalily, Mohsen; Virdee, Bal S.; Ali, Abdul; Shukla, Panchamkumar; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Proof-of-concept is presented of a novel slot antenna structure with two excitation ports. Although this antenna provides a wide impedance bandwidth, its peak gain and optimum radiation efficiency are observed at its mid-band operational frequency. The antenna structure is etched on the top side of a dielectric substrate with a ground plane. The antenna essentially consists of a rectangular patch with two dielectric slots in which multiple coupled patch arms embedded with H-shaped slits are loaded. The two dielectric slots are isolated from each other with a large H-shaped slit. The radiation characteristics of the proposed antenna in terms of impedance bandwidth, gain and efficiency can be significantly improved by simply increasing the number of radiation arms and modifying their dimensions. The antenna’s performance was verified by building and testing three prototype antennas. The final optimized antenna exhibits a fractional bandwidth of 171% (0.5–6.4 GHz) with a peak gain and maximum radiation efficiency of 5.3 dBi and 75% at 4.4 GHz, respectively. The antenna has physical dimensions of 27×37×1.6 mm3 corresponding to electrical size of 0.0452λ0 ×0.0627λ0 ×0.0026λ0,where λ0 is freespace wavelength at 0.5 GHz. The antenna is compatible for integration in handsets and other broadband wireless systems that operate over L-, S-, and C-bands.
Open Access
High-gain metasurface in polyimide on-chip antenna based on CRLH-TL for sub-terahertz integrated circuits
(Nature Research, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a novel on-chip antenna using standard CMOS-technology based on metasurface implemented on two-layers polyimide substrates with a thickness of 500 μm. The aluminium ground-plane with thickness of 3 μm is sandwiched between the two-layers. Concentric dielectric-rings are etched in the ground-plane under the radiation patches implemented on the top-layer. The radiation patches comprise concentric metal-rings that are arranged in a 3 × 3 matrix. The antennas are excited by coupling electromagnetic energy through the gaps of the concentric dielectric-rings in the ground-plane using a microstrip feedline created on the bottom polyimide-layer. The open-ended feedline is split in three-branches that are aligned under the radiation elements to couple the maximum energy. In this structure, the concentric metal-rings essentially act as series left-handed capacitances CL that extend the effective aperture area of the antenna without affecting its dimensions, and the concentric dielectric rings etched in the ground-plane act as shunt left-handed inductors LL, which suppress the surface-waves and reduce the substrates losses that leads to improved bandwidth and radiation properties. The overall structure behaves like a metasurface that is shown to exhibit a very large bandwidth of 0.350–0.385 THz with an average radiation gain and efficiency of 8.15dBi and 65.71%, respectively. It has dimensions of 6 × 6 × 1 mm3 that makes it suitable for on-chip implementation.
Open Access
High-isolation antenna array using SIW and realized with a graphene layer for sub-terahertz wireless applications
(Nature Research, 2021) Alibakhshikenari, Mohammad; Virdee, Bal S.; Salekzamankhani, Shahram; Aïssa, Sonia; See, Chan H.; Soin, Navneet; Fishlock, Sam J.; Althuwayb, Ayman Abdulhadi; Abd-Alhameed, Raed; Huynen, Isabelle; McLaughlin, James A.; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
This paper presents the results of a study on developing an effective technique to increase the performance characteristics of antenna arrays for sub-THz integrated circuit applications. This is essential to compensate the limited power available from sub-THz sources. Although conventional array structures can provide a solution to enhance the radiation-gain performance however in the case of small-sized array structures the radiation properties can be adversely affected by mutual coupling that exists between the radiating elements. It is demonstrated here the effectiveness of using SIW technology to suppress surface wave propagations and near field mutual coupling effects. Prototype of 2x3 antenna arrays were designed and constructed on a polyimide dielectric substrate with thickness of 125 mu m for operation across 0.19-0.20 THz. The dimensions of the array were 20x13.5x0.125 mm(3). Metallization of the antenna was coated with 500 nm layer of Graphene. With the proposed technique the isolation between the radiating elements was improved on average by 22.5 dB compared to a reference array antenna with no SIW isolation. The performance of the array was enhanced by transforming the patch to exhibit metamaterial characteristics. This was achieved by embedding the patch antennas in the array with sub-wavelength slots. Compared to the reference array the metamaterial inspired structure exhibits improvement in isolation, radiation gain and efficiency on average by 28 dB, 6.3 dBi, and 34%, respectively. These results show the viability of proposed approach in developing antenna arrays for application in sub-THz integrated circuits.
Open Access
High-isolation leaky-wave array antenna based on CRLH-metamaterial implemented on SIW with ±30° frequency beam-scanning capability at millimetre-waves
(MDPI, 2019) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
The paper presents a feasibility study on the design of a new metamaterial leaky-wave antenna (MTM-LWA) used in the construction of a 1 × 2 array which is implemented using substrate-integrated waveguide (SIW) technology for millimetre-wave beamforming applications. The proposed 1 × 2 array antenna consists of two LWAs with metamaterial unit-cells etched on the top surface of the SIW. The metamaterial unit-cell, which is an E-shaped transverse slot, causes leakage loss and interrupts current flow over SIW to enhance the array’s performance. The dimensions of the LWA are 40 × 10 × 0.75 mm3. Mutual-coupling between the array elements is suppressed by incorporating a metamaterial shield (MTM-shield) between the two antennas in the array. The LWA operates over a frequency range of 55–65 GHz, which is corresponding to 16.66% fractional bandwidth. The array is shown to exhibit beam-scanning of ±30° over its operating frequency range. Radiation gain in the backward (−30°), broadside (0°), and forward (+30°) directions are 8.5 dBi, 10.1 dBi, and 9.5 dBi, respectively. The decoupling slab is shown to have minimal effect on the array’s performance in terms of impedance bandwidth and radiation specifications. The MTM-shield is shown to suppress the mutual coupling by ~25 dB and to improve the radiation gain and efficiency by ~1 dBi and ~13% on average, respectively.
Open Access
High-performance 50μm silicon-based on-chip antenna with high port-to-port isolation implemented by metamaterial and SIW concepts for THz integrated systems
(IEEE, 2019) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A novel 50μm Silicon-based on-chip antenna is presented that combines metamaterial (MTM) and substrate integrated waveguide (SIW) technologies for integration in THz circuits operating from 0.28 to 0.30 THz. The antenna structure comprises a square patch antenna implemented on a Silicon substrate with a ground-plane. Embedded diagonally in the patch are two T-shaped slots and the edges of the patch is short-circuited to the ground-plane with metal vias, which convert the structure into a substrate integrated waveguide. This structure reduces loss resulting from surface waves and Silicon dielectric substrate. The modes in the structure can be excited through two coaxial ports connected to the patch from the underside of the Silicon substrate. The proposed antenna structure is essentially transformed to exhibit metamaterial properties by realizing two T-shaped slots, which enlarges the effective aperture area of the miniature antenna and significantly enhances its impedance bandwidth and radiation characteristics between 0.28 THz to 0.3 THz. It has an average gain and efficiency of 4.5dBi and 65%, respectively. In addition, it is a self-isolated structure with high isolation of better than 30dB between the two ports. The on-chip antenna has dimensions of 800x800x60μm3
Open Access
Interaction between closely packed array antenna elements using meta-surface for applications such as MIMO systems and synthetic aperture radars
(Wiley, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; Shukla, Panchamkumar; See, Chan H.; Abd-Alhameed, Raed; Khalily, Mohsen; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
The paper presents a technique to enhance the isolation between adjacent radiating elements that is common in densely packed antenna arrays. Such antennas provide frequency beam-scanning capability needed in multiple-input multiple-output (MIMO) systems and synthetic aperture radars. The method proposed here uses a metamaterial decoupling slab (MTM-DS), which is located between radiating elements, to suppress mutual coupling between the elements that would otherwise degrade the antenna efficiency and performance in both the transmit and receive mode. The proposed MTM-DS consists of mirror imaged E-shaped slits engraved on a microstrip patch with inductive stub. Measured results confirm over 9–11 GHz with no MTM-DS the average isolation (S12) is −27 dB; however, with MTM-DS the average isolation improves to −38 dB. With this technique the separation between the radiating element can be reduced to 0.66λ0, where λ0 is free space wavelength at 10 GHz. In addition, with this technique there is 15% improvement in operating bandwidth. At frequencies of high impedance match of 9.95 and 10.63 GHz the gain is 4.52 and 5.40 dBi, respectively. Furthermore, the technique eliminates poor front-to-back ratio encountered in other decoupling methods. MTM-DS is also relatively simple to implement. Assuming adequate space is available between adjacent radiators the MTM-DS can be fixed retrospectively on existing antenna arrays, which makes the proposed method versatile. ©2018. American Geophysical Union. All Rights Reserved.
Open Access
Mutual-coupling reduction in metamaterial substrate integrated waveguide slotted antenna arrays using metal fence isolators for SAR and MIMO applications
(IEEE, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A new type of mutual coupling reduction technique is applied to metamaterial substrate integrated waveguide (SIW) slotted antenna array. The circular shaped reference SIW antenna array is constructed from Alumina substrate with dimensions of 40×5×1.5 mm3. Embedded in the reference antenna are 38 slots with dimensions of 2×1×1.5mm3. The reference SIW antenna operates over X-to Ku-bands with average isolation between the radiation slots of approximately-10Db. Isolation was increased by inserting metal fence isolators (MFIs) between the radiation slots, which increased the isolation by an average of 13dB. In addition, the antenna's impedance matching bandwidth is improved with no degradation in the radiation patterns. With MFIs the maximum gain achieved improves by ~10%. The technique is simple to implement and proposed for synthetic aperture radar (SAR) and multiple input multiple output (MIMO) applications.
Open Access
New approach to suppress mutual coupling between longitudinal-slotted arrays based on SIW antenna loaded with metal-fences working on VHF/UHF frequency-bands: study, investigation, and principle
(IEEE, 2019) Alibakhshikenari, Mohammad; Virdee, Bal S.; Khalily, Mohsen; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this work it is demonstrated that substrate integrated waveguide longitudinal slotted array antenna (SIWLSAA) which is loaded with metal fences exhibits high-isolation across VHF/UHF bands. A reference SIWLSAA used for comparison purpose comprises of 3×6 slotted arrays constructed on the top and bottom sides of the FR-4 lossy substrate has maximum isolation of -63 dB between its radiation slots. Improvement in isolation is demonstrated using a simple new technique based on inserting a metal fence between each row of slot arrays. The resulting isolation is shown to be is better than -83 dB across 200 MHz to 1.0 GHz with gain greater than 1.5 dBi, and side-lobe level less than - 40 dB. The proposed SIWLSAA is compact and has dimensions of 40×10×5 mm 3 (0.026?×0.006?×0.0020) where ? is 200 MHz. The proposed structure should find application in multiple-input multiple-output (MIMO) and radar systems.
Open Access
A new study to suppress mutual-coupling between waveguide slot array antennas based on metasurface bulkhead for MIMO systems
(IEEE, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; Khalily, Mohsen; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper, a new method is proposed to reduce mutual coupling between waveguide slot array (WSA) antennas based on metasurface technology. This is achieved by placing a metasurface bulkhead between the two WSA antennas. Performance of the dual-waveguide antenna structure is shown to substantially enhance when compared against an identical reference WSA antenna with no metasurface. WSA antennas used in the study has dimensions 40×20×5mm 3 and operates over 1.7-3.66 GHz, which corresponds to a fractional bandwidth of 73.13%. The average isolation of the reference WSA antennas is -20 dB; however, with a metasurface bulkhead the isolation is shown to increase to -36.5 dB. In addition, the bandwidth extends by ~10%, and the gain improves by 14.66%. The proposed method is should find application in MIMO systems where high isolation between neighbouring radiation elements is required to improve the antenna characteristics, and mimimise array phase errors, which is necessary to enhance the system performance.
Embargo
A new waveguide slot array antenna with high isolation and high antenna bandwidth operation on Ku- and K- Bands for radar and MIMO systems
(IEEE, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Limiti, Ernesto; Falcone Lanas, Francisco; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper a novel technique is proposed to reduce the mutual coupling between the radiating elements of a waveguide slot array antenna. This is achieved by inserting slots between the waveguide oval shaped slots. The reference waveguide array antenna used in the study was implemented with an arrangement of 3×5 oval shaped slots. By incorporating linear slots between the radiating oval shaped slots in both horizontal and vertical directions significant reduction in mutual coupling is achieved of 24 dB, 20 dB, and 32 dB in the frequency bands of 12.95-13.75 GHz (Ku-band), 15.45-16.85 GHz (Ku-band), and 18.85-23.0 GHz (K-band), respectively. Edge-to-edge distance between the slot radiators is 0.2λ, which is at least twofold smaller than conventional array antennas. With the slot isolators the antenna's minimum and maximum gains improve by 53.5% and 25.5%, respectively. In addition, the radiation patterns are unaffected. The proposed method is simple to implement, low cost solution mass production. © 2018 European Microwave Association.
Open Access
A novel 0.3-0.31 THz GaAs-based transceiver with on-chip slotted metamaterial antenna based on SIW technology
(IEEE, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper presents a novel on-chip antenna with fully integrated 0.3-0.31 THz transceiver is implemented on 0.5μm GaAs substrate, and comprises a voltage-controlled oscillator (VCO), a buffer amplifier, a modulator stage, a power-amplifier, a frequency-tripler, and an on-chip antenna. The proposed on-chip antenna design is based on metamaterial (MTM) slots and substrate integrated waveguide (SIW) technologies. The SIW antenna operates as a high-pass filter and an on-chip radiator to suppress the unwanted harmonics and radiate the desired signal, respectively. Dimensions of the on-chip antenna are 2×1×0.0006 mm3. The proposed on-chip antenna has an average radiation gain and efficiency of >1.0 dBi and 55%, respectively. The transceiver provides an average output power of-15 dBm over 0.3-0.31 THz, which is suitable for near-field active imaging applications at terahertz region.
Open Access
Optimum power transfer in RF front end systems using adaptive impedance matching technique
(Nature Research, 2021) Alibakhshikenari, Mohammad; Virdee, Bal S.; Azpilicueta Fernández de las Heras, Leyre; See, Chan H.; Abd-Alhameed, Raed; Althuwayb, Ayman Abdulhadi; Falcone Lanas, Francisco; Huynen, Isabelle; Denidni, Tayeb A.; Limiti, Ernesto; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación
Matching the antenna’s impedance to the RF-front-end of a wireless communications system is challenging as the impedance varies with its surround environment. Autonomously matching the antenna to the RF-front-end is therefore essential to optimize power transfer and thereby maintain the antenna’s radiation efficiency. This paper presents a theoretical technique for automatically tuning an LC impedance matching network that compensates antenna mismatch presented to the RF-front-end. The proposed technique converges to a matching point without the need of complex mathematical modelling of the system comprising of non-linear control elements. Digital circuitry is used to implement the required matching circuit. Reliable convergence is achieved within the tuning range of the LC-network using control-loops that can independently control the LC impedance. An algorithm based on the proposed technique was used to verify its effectiveness with various antenna loads. Mismatch error of the technique is less than 0.2%. The technique enables speedy convergence (< 5 µs) and is highly accurate for autonomous adaptive antenna matching networks.
Open Access
Overcome the limitations of performance parameters of on-chip antennas based on metasurface and coupled feeding approaches for applications in system-on-chip for THz integrated-circuits
(IEEE, 2020) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This paper proposes a new solution to improve the performance parameters of on-chip antenna designs on standard CMOS silicon (Si.) technology. The proposed method is based on applying the metasurface technique and exciting the radiating elements through coupled feed mechanism. The on-chip antenna is constructed from three layers comprising Si.-GND-Si. layers, so that the ground (GND) plane is sandwiched between two Si. layers. The silicon and ground-plane layers have thicknesses of 20mu m and 5mu m, respectively. The 3×3 array consisting of the asterisk-shaped radiating elements has implemented on the top silicon layer by applying the metasurface approach. Three slot lines in the ground-plane are modelled and located directly under the radiating elements. The radiating elements are excited through the slot-lines using an open-circuited microstrip-line constructed on the bottom silicon layer. The proposed method to excite the structure is based on the coupled feeding mechanism. In addition, by the proposed feeding method the on-chip antenna configuration supresses the substrate losses and surface-waves. The antenna exhibits a large impedance bandwidth of 60GHz from 0.5THz to 0.56THz with an average radiation gain and efficiency of 4.58dBi and 25.37%, respectively. The proposed structure has compact dimensions of 200×200×45μm3. The results shows that, the proposed technique is therefore suitable for on-chip antennas for applications in system-on-chip for terahertz (THz) integrated circuits.
Open Access
Silicon-based 0.450-0.475 THz series-fed double dielectric resonator on-chip antenna array based on metamaterial properties for integrated-circuits
(IEEE, 2019) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
The antenna array designed to operate over 0.450-0.475 Terahertz comprises two dielectric resonators (DRs) that are stacked vertically on top of each other and placed on the surface of the slot antenna fabricated on a silicon substrate using standard CMOS technology. The slot created in the silicon substrate is meandering and is surrounded by metallic via-wall to prevent energy dissipation. The antenna has a maximum gain of 4.5dBi and radiation efficiency of 45.7% at 0.4625 THz. The combination of slot and vias transform the antenna to a metamaterial structure that provides a relatively small antenna footprint. The proposed series-fed double DRs on-chip antenna array is useful for applications in THz integrated circuits.
Open Access
Study on antenna mutual coupling suppression using integrated metasurface isolator for SAR and MIMO applications
(IEEE, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Falcone Lanas, Francisco; Andujar, A.; Anguera, J.; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A metasurface based decoupling structure that is composed of a square-wave slot pattern with exaggerated corners that is implemented on a rectangular microstrip provides high-isolation between adjacent patch antennas for Synthetic Aperture Radar (SAR) and Multi-Input-Multi-Output (MIMO) systems. The proposed 1-2 symmetric array antenna integrated with the proposed decoupling isolation structure is designed to operate at ISM bands of X, Ku, K, and Ka. With the proposed mutual coupling suppression technique (i) the average isolation in the respective ISM bands listed above is 7 dB, 10 dB, 5 dB, and 10 dB; and (ii) edge-to-edge gap between adjacent radiation elements is reduced to 10 mm (0.28λ). The average antenna gain improvement with the metasurface isolator is 2 dBi. © 2018 European Microwave Association.
Open Access
Study on isolation improvement between closely-packed patch antenna arrays based on fractal metamaterial electromagnetic bandgap structures
(Institution of Engineering and Technology, 2018) Alibakhshikenari, Mohammad; Virdee, Bal S.; See, Chan H.; Abd-Alhameed, Raed; Ali, Abdul; Hussein Ali, Ammar; Falcone Lanas, Francisco; Limiti, Ernesto; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A decoupling metamaterial (MTM) configuration based on fractal electromagnetic-bandgap (EMBG) structure is shown to significantly enhance isolation between transmitting and receiving antenna elements in a closely-packed patch antenna array. The MTM-EMBG structure is cross-shaped assembly with fractal-shaped slots etched in each arm of the cross. The fractals are composed of four interconnected-'Y-shaped' slots that are separated with an inverted-'T-shaped' slot. The MTM-EMBG structure is placed between the individual patch antennas in a 2 × 2 antenna array. Measured results show the average inter-element isolation improvement in the frequency band of interest is 17, 37 and 17 dB between radiation elements #1 & #2, #1 & #3, and #1 & #4, respectively. With the proposed method there is no need for using metallic-via-holes. The proposed array covers the frequency range of 8-9.25 GHz for X-band applications, which corresponds to a fractional-bandwidth of 14.5%. With the proposed method the edge-to-edge gap between adjacent antenna elements can be reduced to 0.5λ0 with no degradation in the antenna array's radiation gain pattern. Across the array's operating band, the measured gain varies between 4 and 7 dBi, and the radiation efficiency varies from 74.22 and 88.71%. The proposed method is applicable in the implementation of closely-packed patch antenna arrays used in SAR and MIMO systems. © 2018, The Institution of Engineering and Technology.