Special Issue "Intelligent Antennas"

A special issue of Electronics (ISSN 2079-9292). This special issue belongs to the section "Microwave and Wireless Communications".

Deadline for manuscript submissions: 31 May 2019

Special Issue Editor

Guest Editor
Prof. Pedram Mousavi

Department of Mechanical Engineering, University of Alberta, Edmonton T6G 1H9, Canada
Website | E-Mail
Interests: reconfigurable antennas, sensor-antennas, phased array antennas, smart antennas

Special Issue Information

Dear Colleagues,

The unprecedented emergence of new wireless applications in recent years pervades all aspect of our lives. To handle the demand, the telecommunication industry will develop the 5th generation of networks. These devices will be used in many applications such as telecommunication networks, health care, sensing, imaging, oil and gas, military, transportation, wearable devices, smart appliances and smart buildings. Hosting all these applications and accommodating future applications in a single platform will require reconfigurable, flexible, multi-band, energy smart (such as harvesting) and intelligent antennas. This Special Issue will present scholarly papers that address critical issues in theory, design, manufacturing (use of new materials and manufacturing process such as 3D printing) and measurements (such as fast near-field measurements) of intelligent antennas.

Prof. Pedram Mousavi
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Reconfigurable antennas
  • Sensor antennas
  • Phased array antennas
  • 3D printing of antennas
  • Antenna for wireless power transfer
  • New materials for antennas
  • Flexible antennas

Published Papers (12 papers)

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Open AccessFeature PaperArticle
Fence Shaping of Substrate Integrated Fan-Beam Electric Dipole for High-Band 5G
Electronics 2019, 8(5), 545; https://doi.org/10.3390/electronics8050545
Received: 17 April 2019 / Revised: 12 May 2019 / Accepted: 13 May 2019 / Published: 15 May 2019
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Abstract
This work presents fence shaping for dipole antenna operating at 5G high-band frequencies. A via fence is employed around the dipole to suppress back radiation. By varying the geometric shape of the fence, the dipole’s radiation characteristics can be controlled, which adds an [...] Read more.
This work presents fence shaping for dipole antenna operating at 5G high-band frequencies. A via fence is employed around the dipole to suppress back radiation. By varying the geometric shape of the fence, the dipole’s radiation characteristics can be controlled, which adds an additional degree of freedom to the design. This was investigated by studying different fence shapes, namely rectangular-, U-, and V-shaped fences. The wide bandwidth (higher than 6.5 GHz) centered around 28 GHz, and the stable radiation performance from 24 GHz to 32 GHz made the proposed structure capable of supporting multiple 5G frequency bands and the fence shaping help modulate the gain and HPBW of the dipole. All fabricated prototypes attained front-to-back radiation ratio (F/B) higher than 36 dB, with good gain/HPBW performances of 14.1 dBi/103.7°, 13.5dBi/118°, and 12.6 dBi/133° from the V-fence, U-fence, and rectangular fence 4 × 1 arrays, respectively. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Slot-Loaded Microstrip Patch Sensor Antenna for High-Sensitivity Permittivity Characterization
Electronics 2019, 8(5), 502; https://doi.org/10.3390/electronics8050502
Received: 2 April 2019 / Revised: 29 April 2019 / Accepted: 30 April 2019 / Published: 7 May 2019
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Abstract
A slot-loaded microstrip patch sensor antenna is proposed to enhance sensitivity in measuring the permittivity of planar materials. A thin rectangular slot was etched along the radiating edge of a rectangular patch antenna fed by a microstrip transmission line. Two resonant frequencies were [...] Read more.
A slot-loaded microstrip patch sensor antenna is proposed to enhance sensitivity in measuring the permittivity of planar materials. A thin rectangular slot was etched along the radiating edge of a rectangular patch antenna fed by a microstrip transmission line. Two resonant frequencies were created at a lower frequency compared to the single resonant frequency of a conventional ordinary patch antenna. The sensitivity of the proposed slot-loaded patch antenna was measured by the shift in the resonant frequency of the input reflection coefficient when the planar dielectric superstrate was placed above the patch, and was compared with that of a conventional patch antenna without the slot. The two antennas were designed and fabricated on a 0.76 mm-thick RF-35 substrate for the first resonant frequency to resonate at 2.5 GHz under unloaded conditions. Five different standard dielectric samples with dielectric constants ranging from 2.17 to 10.2 were tested for sensitivity comparison. The experiment results showed that the measured sensitivity of the proposed patch antenna were 3.54 to 4.53 times higher, compared to a conventional patch antenna, for the five samples. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Dual Band-Notched Rectangular Dielectric Resonator Antenna with Tunable Characteristic
Electronics 2019, 8(5), 472; https://doi.org/10.3390/electronics8050472
Received: 1 April 2019 / Revised: 25 April 2019 / Accepted: 26 April 2019 / Published: 28 April 2019
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Abstract
A dual band-notched reconfigurable dielectric resonator antenna (DRA) is proposed in this paper. A rectangular dielectric resonator excited by stepped offset microstrip feedline generates multiple resonant modes for wideband performance. Moreover, the typical stepped impedance feedline and partial ground plane with one rectangular [...] Read more.
A dual band-notched reconfigurable dielectric resonator antenna (DRA) is proposed in this paper. A rectangular dielectric resonator excited by stepped offset microstrip feedline generates multiple resonant modes for wideband performance. Moreover, the typical stepped impedance feedline and partial ground plane with one rectangular notch are adopted for contributing for better impedance matching. On this basis, a five-line coupler resonator (FLCR) composed by inverted U-shaped and 山-shaped structures is introduced as a bandstop filter in the microstrip feedline, and dual rejected bands are created. Tunable notched frequencies are achieved by the varactor between these two structures. The proposed antenna size is 24 × 28 × 5.637 mm3. For the presented work, both simulated and measured results for the proposed tunable antenna ranging from 5.3 to 5.84 GHz and from 8.74 to 8.98 GHz within the wide bandwidth of 6.06 GHz are presented, demonstrating the accuracy of this design. There capabilities make the proposed antenna applicable for wideband systems with the requirement of avoiding interferences. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
A Design Rule to Reduce the Human Body Effect on Wearable PIFA Antennas
Electronics 2019, 8(2), 244; https://doi.org/10.3390/electronics8020244
Received: 30 January 2019 / Revised: 12 February 2019 / Accepted: 14 February 2019 / Published: 21 February 2019
Cited by 1 | PDF Full-text (10084 KB) | HTML Full-text | XML Full-text | Correction
Abstract
The robustness of wearable Ultra-High Frequency (UHF)-band planar inverted-F Antennas (PIFAs) with respect to coupling with the human body is an extremely difficult challenge for the designer. In this work a design strategy is presented to help the designer to adequately shape and [...] Read more.
The robustness of wearable Ultra-High Frequency (UHF)-band planar inverted-F Antennas (PIFAs) with respect to coupling with the human body is an extremely difficult challenge for the designer. In this work a design strategy is presented to help the designer to adequately shape and extend the antenna ground plane, which has been derived by accurately analyzing the distribution of the electric and magnetic energy densities of the antenna in a region around the antenna borders. The optimal extension of the ground plane will be discussed for three different grounded antennas, both in terms of free space wavelength, and in terms of electric energy density magnitude. Following these rules, the antenna robustness with respect to the coupling with the human body can be significantly improved, but with a minimal impact on the antenna size. The antenna robustness has been successfully tested considering several models for the human phantom in the simulation environment. The numerical simulations, performed using Computer Simulation Technology (CST) Microwave Studio, have been confirmed by experimental data measured for one of the analyzed grounded antenna configurations. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Compact UWB Band-Notched Antenna with Integrated Bluetooth for Personal Wireless Communication and UWB Applications
Electronics 2019, 8(2), 158; https://doi.org/10.3390/electronics8020158
Received: 24 November 2018 / Revised: 25 December 2018 / Accepted: 14 January 2019 / Published: 1 February 2019
Cited by 3 | PDF Full-text (3065 KB) | HTML Full-text | XML Full-text
Abstract
A compact band-notched UWB (Ultra-Wide Band) antenna with integrated Bluetooth is developed for personal wireless communication and UWB applications. The antenna operates at the UWB frequency band (3.1–10.6 GHz) as well as Bluetooth (2.4–2.484 GHz), with band-notch characteristics at the Wireless Local Area [...] Read more.
A compact band-notched UWB (Ultra-Wide Band) antenna with integrated Bluetooth is developed for personal wireless communication and UWB applications. The antenna operates at the UWB frequency band (3.1–10.6 GHz) as well as Bluetooth (2.4–2.484 GHz), with band-notch characteristics at the Wireless Local Area Network (WLAN) frequency band (5–6 GHz). A new technique of integrating Bluetooth within a UWB band-notched antenna is developed and analyzed. The UWB frequency band is realized by utilizing a conventional cylindrical radiating patch and a modified partial ground plane. The Bluetooth band is integrated using a miniaturized resonator with the addition of capacitors. Further, to mitigate the interference of the WLAN frequency band within the UWB spectrum, a conventional slot resonator is integrated within the radiator to achieve the task. The antenna is designed and fabricated, and its response in each case is provided. Moreover, the antenna exhibits a good radiation pattern with a stable gain in the passband. The present antenna is also compared to state-of-the-art structures proposed in the literature. The miniaturized dimensions (30 × 31 mm2) of the antenna make it an excellent candidate for UWB and personal wireless communication applications. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Low Profile Sinuous Slot Antenna for UWB Sensor Networks
Electronics 2019, 8(2), 127; https://doi.org/10.3390/electronics8020127
Received: 24 December 2018 / Revised: 17 January 2019 / Accepted: 21 January 2019 / Published: 25 January 2019
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Abstract
This article describes the design and implementation of a low-profile sinuous slot antenna, intended for ultra-wideband (UWB) sensor networks, which can be produced on one conductive layer. The article explains the design and optimization of the sinuous slot antenna and its modifications, including [...] Read more.
This article describes the design and implementation of a low-profile sinuous slot antenna, intended for ultra-wideband (UWB) sensor networks, which can be produced on one conductive layer. The article explains the design and optimization of the sinuous slot antenna and its modifications, including its sinusoidal curve shape. Other modifications were aimed at optimizing the antenna feeding. Desirable properties of the designed and implemented antenna modifications were verified both by simulation and empirically. Experimental measurements of the antenna’s properties were carried out using a vector network analyzer in an anechoic chamber and also by a pulsed UWB radar in the frequency range from 0.1 to 6 GHz. The low-profile antennas were implemented on a Rogers RO3206 substrate. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessFeature PaperArticle
Efficient Large Sparse Arrays Synthesis by Means of Smooth Re-Weighted L1 Minimization
Electronics 2019, 8(1), 83; https://doi.org/10.3390/electronics8010083
Received: 2 November 2018 / Revised: 20 December 2018 / Accepted: 8 January 2019 / Published: 11 January 2019
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Abstract
In this paper, we present an efficient technique for the synthesis of very large sparse arrays, with arbitrary circularly-symmetrical upper bounds for the pattern specifications. The algorithm, which is based on iterative smooth re-weighted L1 minimizations, is very flexible and is capable of [...] Read more.
In this paper, we present an efficient technique for the synthesis of very large sparse arrays, with arbitrary circularly-symmetrical upper bounds for the pattern specifications. The algorithm, which is based on iterative smooth re-weighted L1 minimizations, is very flexible and is capable of achieving very good performances with respect to competitive algorithms. Furthermore, thanks to its efficiency, planar arrays of hundreds of wavelengths can be synthesized with limited computational effort. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Efficient Cumulant-Based Methods for Joint Angle and Frequency Estimation Using Spatial-Temporal Smoothing
Electronics 2019, 8(1), 82; https://doi.org/10.3390/electronics8010082
Received: 16 November 2018 / Revised: 2 January 2019 / Accepted: 7 January 2019 / Published: 10 January 2019
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Abstract
Most non-Gaussian signals in wireless communication array systems contain temporal correlation under a high sampling rate, which can offer more accurate direction of arrival (DOA) and frequency estimates and a larger identifiability. However, in practice, the estimation performance may severely degrade in coloured [...] Read more.
Most non-Gaussian signals in wireless communication array systems contain temporal correlation under a high sampling rate, which can offer more accurate direction of arrival (DOA) and frequency estimates and a larger identifiability. However, in practice, the estimation performance may severely degrade in coloured noise environments. To tackle this issue, we propose real-valued joint angle and frequency estimation (JAFE) algorithms for non-Gaussian signals using fourth-order cumulants. By exploiting the temporal correlation embedded in signals, a series of augmented cumulant matrices is constructed. For independent signals, the DOA and frequency estimates can be obtained, respectively, by leveraging a dual rotational invariance property. For coherent signals, the dual rotational invariance is constructed to estimate the generalized steering vectors, which associates the coherent signals into different groups. Then, the coherent signals in each group can be resolved by performing the forward-backward spatial smoothing. The proposed schemes not only improve the estimation accuracy, but also resolve many more signals than sensors. Besides, it is computationally efficient since it performs the estimation by the polynomial rooting in the real number field. Simulation results demonstrate the superiorities of the proposed estimator to its state-of-the-art counterparts on identifiability, estimation accuracy and robustness, especially for coherent signals. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Characteristic Mode Analysis and Design of Wide Band MIMO Antenna Consisting of Metamaterial Unit Cell
Electronics 2019, 8(1), 68; https://doi.org/10.3390/electronics8010068
Received: 1 December 2018 / Revised: 22 December 2018 / Accepted: 2 January 2019 / Published: 8 January 2019
Cited by 1 | PDF Full-text (7214 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a full wave simulation and characteristic mode-based design of a multiple-input-multiple-output (MIMO) antenna at 5.8 GHz for wireless local area network applications. The driven analysis comprises two antennas that are placed orthogonal to each other. A metamaterial unit structure in [...] Read more.
This paper presents a full wave simulation and characteristic mode-based design of a multiple-input-multiple-output (MIMO) antenna at 5.8 GHz for wireless local area network applications. The driven analysis comprises two antennas that are placed orthogonal to each other. A metamaterial unit structure in the form of a rectangular loop resonator is placed around the antenna element to reduce the electromagnetic interference and to increase the isolation between the two monopoles. A characteristic mode technique is employed to find out the dominant mode of the proposed antenna without a feeding port. It was revealed that mode 1 was the dominant mode among the three modes used. The MIMO antenna is constructed and measured using a vector network analyzer. A good isolation of less than 25 dB was attained with a wide impedance bandwidth of 65.5%. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Compact Antenna for 4G/5G Metal Frame Mobile Phone Applications Using a Tuning Line
Electronics 2018, 7(12), 439; https://doi.org/10.3390/electronics7120439
Received: 20 November 2018 / Revised: 13 December 2018 / Accepted: 13 December 2018 / Published: 14 December 2018
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Abstract
A compact antenna with a 6 mm ground clearance for 4G and 5G metal frame mobile phones is proposed in this paper. The proposed antenna consists of a coupled line, a ground branch, a monopole branch, and a tuning line. The ground branch [...] Read more.
A compact antenna with a 6 mm ground clearance for 4G and 5G metal frame mobile phones is proposed in this paper. The proposed antenna consists of a coupled line, a ground branch, a monopole branch, and a tuning line. The ground branch and the coupled line are used to obtain the lower band (698–960 MHz), the monopole branch is used to improve the match at the lower band and obtain the higher band (1710–2690, 3400–3800 MHz), and the tuning line is used to improve the match at the higher band. The novelty of the proposed antenna is that more modes are excited and work together to obtain multiple working bands, by using the coupled line and the folded branches with the help of the tuning line, and then nine bands are obtained under the conditions of a 6 mm, only, ground clearance and a metal frame environment. A prototype has been fabricated and measured. The measured −6 dB impedance bandwidths are 345 MHz (0.685–1.03 GHz) and 2.16 GHz (1.67–3.83 GHz) at the lower and higher bands, respectively. The LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, and LTE2500 bands for 2G, 3G, 4G, and the 3.5 GHz band that is possible for 5G are covered. The measured efficiencies and patterns are also presented. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
SBL-Based Direction Finding Method with Imperfect Array
Electronics 2018, 7(12), 426; https://doi.org/10.3390/electronics7120426
Received: 27 November 2018 / Revised: 7 December 2018 / Accepted: 10 December 2018 / Published: 11 December 2018
Cited by 1 | PDF Full-text (890 KB) | HTML Full-text | XML Full-text
Abstract
The imperfect array degrades the direction finding performance. In this paper, we investigate the direction finding problem in uniform linear array (ULA) system with unknown mutual coupling effect between antennas. By exploiting the target sparsity in the spatial domain, the sparse Bayesian learning [...] Read more.
The imperfect array degrades the direction finding performance. In this paper, we investigate the direction finding problem in uniform linear array (ULA) system with unknown mutual coupling effect between antennas. By exploiting the target sparsity in the spatial domain, the sparse Bayesian learning (SBL)-based model is proposed and converts the direction finding problem into a sparse reconstruction problem. In the sparse-based model, the off-grid errors are introduced by discretizing the direction area into grids. Therefore, an off-grid SBL model with mutual coupling vector is proposed to overcome both the mutual coupling and the off-grid effect. With the distribution assumptions of unknown parameters including the noise variance, the off-grid vector, the received signals and the mutual coupling vector, a novel direction finding method based on SBL with unknown mutual coupling effect named DFSMC is proposed, where an expectation-maximum (EM)-based step is adopted by deriving the estimation expressions for all the unknown parameters theoretically. Simulation results show that the proposed DFSMC method can outperform state-of-the-art direction finding methods significantly in the array system with unknown mutual coupling effect. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessCorrection
Correction: Casula, G.A. A Design Rule to Reduce the Human Body Effect on Wearable PIFA Antennas. Electronics 2019, 8, 244
Electronics 2019, 8(3), 291; https://doi.org/10.3390/electronics8030291
Received: 5 March 2019 / Accepted: 5 March 2019 / Published: 5 March 2019
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Abstract
In the original version of this article [...] Full article
(This article belongs to the Special Issue Intelligent Antennas)
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