E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Special Issue "Antenna Technologies for Microwave Sensors"

A special issue of Sensors (ISSN 1424-8220).

Deadline for manuscript submissions: 31 December 2019

Special Issue Editor

Guest Editor
Prof. Dr. Mohammad Tariqul Islam

Dept. of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), 43600 UKM, Bangi, Selangor, Malaysia
E-Mail

Special Issue Information

Dear Colleagues,

Microwave sensors have been extensively utilized in various applications. Microwave sensors (physical sensors, chemical sensors, etc.) find useful applications which have gained widespread popularity because of their integration with laptops, tablets, eBook readers, etc. An increasing demand in microwave antenna sensors has been witnessed, using advanced materials and sophisticated electronics, which have facilitated realizing small sizes and sensitive sensors. Microwave antenna sensors find ubiquitous applications, such as in mobile phones, laptops, radio-frequency-identification (RFID), global-positioning-system (GPS) applications, etc., to name a few. Emerging applications have opened new avenues and set new trends for microwave antennas, such as reconfigurable, foldable, and low-cost antennas for airborne, machine-to-machine, the Internet-of-things (IoT), 5G, etc. On the other hand, recently, metamaterial-inspired sensors have become a reality. Metamaterials are made from electrically-small particles. Each of the particles is essentially a resonator. Since the particles are electrically-small, their individual frequency bandwidths are also astoundingly small. This feature makes these particles notoriously unattractive for antenna applications, but highly attractive for sensing applications.

The aim of this Special Issue is to surpass the challenges of microwave components (antennas, and sensors), as well as to contrive antennas and sensing schemes for advanced applications, such as: 1) antennas for physical sensors; 2) metamaterial-based antenna design for sensor applications; 3) self-calibrated and portable sensors; 4) implantable biosensors; and 5) reconfigurable and low-cost antennas.

Prof. Dr. Mohammad Tariqul Islam
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.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 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

  • Sensors
  • Metamaterials
  • Microwaves
  • Electromagnetic Fields
  • Material Sensing
  • Chemical Sensing

Published Papers (23 papers)

View options order results:
result details:
Displaying articles 1-23
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle
Realization of Low Profile Leaky Wave Antennas Using the Bending Technique for Frequency Scanning and Sensor Applications
Sensors 2019, 19(10), 2265; https://doi.org/10.3390/s19102265
Received: 18 April 2019 / Revised: 10 May 2019 / Accepted: 11 May 2019 / Published: 16 May 2019
PDF Full-text (2062 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an efficient transmission line modulation by using the bending technique to realize low profile leaky wave antennas in the Ku-band for frequency scanning and sensor applications. The paper focuses mainly on the bending effects of the transmission line in terms [...] Read more.
This paper proposes an efficient transmission line modulation by using the bending technique to realize low profile leaky wave antennas in the Ku-band for frequency scanning and sensor applications. The paper focuses mainly on the bending effects of the transmission line in terms of the sharpness of edges. The right-hand/left-hand transmission line can be designed in the form of zig-zag pattern with sharp corners and only the right-hand transmission line in the form of sinusoidal patterns with smooth corners. In this presentation, we demonstrate that transmission lines of this kind can be used to realize highly efficient leaky wave antennas with broadband impedance matching and high gain characteristics in the Ku-band. Dispersion analysis and ladder network analysis have been performed for investigating the performance of the proposed designs. The sharpness of the bends periodically distributed along the body of the antenna has been used to our advantage for frequency scanning in the left-hand and right-hand quadrants at different frequencies. The proposed bending technique has been proven to be instrumental in achieving the desired characteristics of low profile leaky wave antennas. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Submersible Printed Sensor Based on a Monopole-Coupled Split Ring Resonator for Permittivity Characterization
Sensors 2019, 19(8), 1936; https://doi.org/10.3390/s19081936
Received: 12 March 2019 / Revised: 9 April 2019 / Accepted: 18 April 2019 / Published: 25 April 2019
PDF Full-text (4902 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This work presents a non-invasive, reusable and submersible permittivity sensor that uses a microwave technique for the dielectric characterization of liquid materials. The proposed device consists of a compact split ring resonator excited by two integrated monopole antennas. The sensing principle is based [...] Read more.
This work presents a non-invasive, reusable and submersible permittivity sensor that uses a microwave technique for the dielectric characterization of liquid materials. The proposed device consists of a compact split ring resonator excited by two integrated monopole antennas. The sensing principle is based on the notch introduced by the resonators in the transmission coefficient, which is affected due to the introduction of the sensor in a new liquid material. Then, a frequency shift of the notch and the Q-factor of the proposed sensor are related with the changes in the surrounding medium. By means of a particular experimental procedure, commercial liquids are employed to obtain the calibration curve. Thus, a mathematical equation is obtained to extract the dielectric permittivity of liquid materials with unknown dielectric properties. A good match between simulated and experimental results is obtained, as well as a high Q-factor, compact size, good sensitivity and high repeatability for use in sensing applications. Sensors like the one here presented could lead to promising solutions for characterizing materials, particularly in determining material properties and quality in the food industry, bio-sensing and other applications. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Patch/Dipole Hybrid-Mode Antenna for Sub-6GHz Communication
Sensors 2019, 19(6), 1358; https://doi.org/10.3390/s19061358
Received: 6 February 2019 / Revised: 10 March 2019 / Accepted: 13 March 2019 / Published: 18 March 2019
PDF Full-text (4302 KB) | HTML Full-text | XML Full-text
Abstract
A low-profile antenna with a high gain and broad bandwidth is proposed for Sub-6GHz communication in this paper. A narrow-band patch mode and a narrow-band dipole mode are shared in one radiator and simultaneously excited to broaden the bandwidth. A compact prototype with [...] Read more.
A low-profile antenna with a high gain and broad bandwidth is proposed for Sub-6GHz communication in this paper. A narrow-band patch mode and a narrow-band dipole mode are shared in one radiator and simultaneously excited to broaden the bandwidth. A compact prototype with a projection size of 0.90 λ0 × 0.78 λ0 and a profile of 0.13 λ00 is the wavelength in the free space at the center of the operating frequency) is fabricated and measured. The measurement demonstrates an impedance bandwidth of 67.50%, covering the frequency range from 2.75 GHz to 5.45 GHz and an average gain of 8.4 dBi in the operating band of 3.0–5.0 GHz. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Cylindrical Dielectric Resonator Antenna-Based Sensors for Liquid Chemical Detection
Sensors 2019, 19(5), 1200; https://doi.org/10.3390/s19051200
Received: 23 February 2019 / Accepted: 5 March 2019 / Published: 8 March 2019
Cited by 1 | PDF Full-text (2752 KB) | HTML Full-text | XML Full-text
Abstract
A compact, cylindrical dielectric resonator antenna (CDRA), using radio frequency signals to identify different liquids is proposed in this paper. The proposed CDRA sensor is excited by a rectangular slot through a 3-mm-wide microstrip line. The rectangular slot has been used to excite [...] Read more.
A compact, cylindrical dielectric resonator antenna (CDRA), using radio frequency signals to identify different liquids is proposed in this paper. The proposed CDRA sensor is excited by a rectangular slot through a 3-mm-wide microstrip line. The rectangular slot has been used to excite the CDRA for H E M 11 mode at 5.25 GHz. Circuit model values (capacitance, inductance, resistance and transformer ratios) of the proposed CDRA are derived to show the true behaviour of the system. The proposed CDRA acts as a sensor due to the fact that different liquids have different dielectric permittivities and, hence, will be having different resonance frequencies. Two different types of CDRA sensors are designed and experimentally validated with four different liquids (Isopropyl, ethanol, methanol and water). Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Left-Handed Metamaterial-Inspired Unit Cell for S-Band Glucose Sensing Application
Sensors 2019, 19(1), 169; https://doi.org/10.3390/s19010169
Received: 27 November 2018 / Revised: 23 December 2018 / Accepted: 24 December 2018 / Published: 5 January 2019
Cited by 2 | PDF Full-text (3536 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an oval-shaped sensor design for the measurement of glucose concentration in aqueous solution. This unit cell sensing device is inspired by metamaterial properties and is analytically described for better parametric study. The mechanism of the sensor is a sensing layer [...] Read more.
This paper presents an oval-shaped sensor design for the measurement of glucose concentration in aqueous solution. This unit cell sensing device is inspired by metamaterial properties and is analytically described for better parametric study. The mechanism of the sensor is a sensing layer with varying permittivity placed between two nozzle-shaped microstrip lines. Glucose aqueous solutions were characterized considering the water dielectric constant, from 55 to 87, and were identified with a transmission coefficient at 3.914 GHz optimal frequency with double negative (DNG) metamaterial properties. Consequently, the sensitivity of the sensor was estimated at 0.037 GHz/(30 mg/dL) glucose solution. The design and analysis of this sensor was performed using the finite integration technique (FIT)-based Computer Simulation Technology (CST) microwave studio simulation software. Additionally, parametric analysis of the sensing characteristics was conducted using experimental verification for the justification. The performance of the proposed sensor demonstrates the potential application scope for glucose level identification in aqueous solutions regarding qualitative analysis. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Experimental Breast Phantom Imaging with Metamaterial-Inspired Nine-Antenna Sensor Array
Sensors 2018, 18(12), 4427; https://doi.org/10.3390/s18124427
Received: 20 October 2018 / Revised: 8 December 2018 / Accepted: 10 December 2018 / Published: 14 December 2018
Cited by 1 | PDF Full-text (23873 KB) | HTML Full-text | XML Full-text
Abstract
An experimental system for early screening of a breast tumor is presented in this article. The proposed microwave imaging (MI) system consists of a moveable array of nine improved negative-index metamaterial (MTM)-loaded ultrawideband (UWB) antenna sensor with incorporation of a corresponding SRR (split-ring [...] Read more.
An experimental system for early screening of a breast tumor is presented in this article. The proposed microwave imaging (MI) system consists of a moveable array of nine improved negative-index metamaterial (MTM)-loaded ultrawideband (UWB) antenna sensor with incorporation of a corresponding SRR (split-ring resonator) and CLS (capacitively loaded strip) structure, in a circular array, the stepper motor-based array-mounting stand, the adjustable phantom hanging platform, an RF switching system to control the receivers, and a personal computer-based signal processing and image reconstruction unit using MATLAB. The improved antenna comprises of four-unit cells along one axis, where an individual unit cell integrates a balancing SRR and CLS pair, which makes the antenna radiation omnidirectional over the operating frequencies. The electrical dimensions of this proposed antenna are 0.28λ × 0.20λ × 0.016λ, measured at the lowest operating frequency of 2.97 GHz as the operating bandwidth of this is in between 2.97–15 GHz (134.82% bandwidth), with stable directional radiation pattern. SP8T 8 port switch is used to enable the eight receiver antennas to sequentially send a 3–8.0 GHz microwave signal to capture the backscattered signal by MATLAB software. A low-cost realistic homogeneous breast phantom with tumor material is developed and measured to test the capability of the imaging system to detect the breast tumors. A post-processing delay-multiply-and-sum (DMAS) algorithm is used to process the recorded backscatter signal to get an image of the breast phantom, and to accurately identify the existence and located area of multiple breast tumor tissues. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Circularly Polarized Broadband Printed Antenna for Wireless Applications
Sensors 2018, 18(12), 4261; https://doi.org/10.3390/s18124261
Received: 17 October 2018 / Revised: 25 November 2018 / Accepted: 30 November 2018 / Published: 4 December 2018
Cited by 1 | PDF Full-text (11887 KB) | HTML Full-text | XML Full-text
Abstract
A simple, compact sickle-shaped printed antenna with a slotted ground plane is designed and developed for broadband circularly polarized (CP) radiation. The sickle-shaped radiator with a tapered feed line and circular slotted square ground plane are utilized to realize the wideband CP radiation [...] Read more.
A simple, compact sickle-shaped printed antenna with a slotted ground plane is designed and developed for broadband circularly polarized (CP) radiation. The sickle-shaped radiator with a tapered feed line and circular slotted square ground plane are utilized to realize the wideband CP radiation feature. With optimized dimensions of 0.29λ × 0.29λ × 0.012λ at 2.22 GHz frequency for the realized antenna parameters, the measured results display that the antenna has a 10 dB impedance bandwidth of 7.70 GHz (126.85%; 2.22–9.92 GHz) and a 3 dB axial ratio (AR) bandwidth of 2.64 GHz (73.33%; 2.28–4.92 GHz). The measurement agrees well with simulation, which proves an excellent circularly polarized property. For verification, the mechanism of band improvement and circular polarization are presented, and the parametric study is carried out. Since, the proposed antenna is a simple design structure with broad impedance and AR bandwidth, which is a desirable feature as a candidate for various wireless communication systems. Because of the easy printed structure and scaling the dimension with broadband CP characteristics, the realized antenna does incorporate in a number of CP wireless communication applications. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Paper-Based Flexible Antenna for Wearable Telemedicine Applications at 2.4 GHz ISM Band
Sensors 2018, 18(12), 4214; https://doi.org/10.3390/s18124214
Received: 12 October 2018 / Revised: 12 November 2018 / Accepted: 13 November 2018 / Published: 1 December 2018
PDF Full-text (5242 KB) | HTML Full-text | XML Full-text
Abstract
This paper demonstrates the performance of a potential design of a paper substrate-based flexible antenna for intrabody telemedicine systems in the 2.4 GHz industrial, scientific, and medical radio (ISM) bands. The antenna was fabricated using 0.54 mm thick flexible photo paper and 0.03 [...] Read more.
This paper demonstrates the performance of a potential design of a paper substrate-based flexible antenna for intrabody telemedicine systems in the 2.4 GHz industrial, scientific, and medical radio (ISM) bands. The antenna was fabricated using 0.54 mm thick flexible photo paper and 0.03 mm copper strips as radiating elements. Design and performance analyses of the antenna were performed using Computer Simulation Technology (CST) Microwave Studio software. The antenna performances were investigated based on the reflection coefficient in normal and bent conditions. The total dimensions of the proposed antenna are 40 × 35 × 0.6 mm3. The antenna operates at 2.33–2.53 GHz in the normal condition. More than an 8% fractional bandwidth is expressed by the antenna. Computational analysis was performed at different flexible curvatures by bending the antenna. The minimum fractional bandwidth deviation is 5.04% and the maximum is 24.97%. Moreover, it was mounted on a homogeneous phantom muscle and a four-layer human tissue phantom. Up to a 70% radiation efficiency with a 2 dB gain was achieved by the antenna. Finally, the performance of the antenna with a homogeneous phantom muscle was measured and found reliable for wearable telemedicine applications. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Resonator-Inspired Metamaterial Sensor: Design and Experimental Validation for Measuring Thickness of Multi-Layered Structures
Sensors 2018, 18(12), 4213; https://doi.org/10.3390/s18124213
Received: 1 August 2018 / Revised: 13 October 2018 / Accepted: 16 October 2018 / Published: 1 December 2018
PDF Full-text (4245 KB) | HTML Full-text | XML Full-text
Abstract
A digit 8-shaped resonator inspired metamaterial is proposed herein for sensor applications. The resonator is surrounded by a ground frame and excited by a microstrip feedline. The measurement of the sensor can be performed using common laboratory facilities in lieu of using the [...] Read more.
A digit 8-shaped resonator inspired metamaterial is proposed herein for sensor applications. The resonator is surrounded by a ground frame and excited by a microstrip feedline. The measurement of the sensor can be performed using common laboratory facilities in lieu of using the waveguide, as the resonator, ground frame, and feedline are all on the same microstrip. To achieve metamaterial properties, more than one unit cell is usually utilized, whereas, in this work, a single cell was used to achieve the metamaterial characteristics. The properties of the metamaterial were investigated to find the relationship between the simulation and measurements. The proposed metamaterial sensor shows considerable sensitivity in sensor application. For the sensor application, FR4 and Rogers RO4350 materials were used as the over-layer. The sensor can measure dielectric thickness with a sensitivity of 625 MHz/mm, 468 MHz/mm, and 354 MHz/mm for the single over-layer, double over-layers, and multiple over-layers, respectively. The proposed prototype can be utilized in several applications where metamaterial characteristics are required. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Flexible Radio-Frequency Identification (RFID) Tag Antenna for Sensor Applications
Sensors 2018, 18(12), 4212; https://doi.org/10.3390/s18124212
Received: 26 August 2018 / Revised: 19 September 2018 / Accepted: 26 September 2018 / Published: 30 November 2018
PDF Full-text (1955 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an inkjet-printed flexible Radio-Frequency Identification (RFID) tag antenna is proposed for an ultra-high frequency (UHF) sensor application. The proposed tag antenna facilitates a system-level solution for low-cost and faster mass production of RFID passive tag antenna. The tag antenna consists [...] Read more.
In this paper, an inkjet-printed flexible Radio-Frequency Identification (RFID) tag antenna is proposed for an ultra-high frequency (UHF) sensor application. The proposed tag antenna facilitates a system-level solution for low-cost and faster mass production of RFID passive tag antenna. The tag antenna consists of a modified meander line radiator with a semi-circular shaped feed network. The structure is printed on photo paper using silver nanoparticle conductive ink. The generic design outline, as well as tag antenna performances for several practical application aspects are investigated. The simulated and measured results verify the coverage of universal UHF RFID band with an omnidirectional radiation pattern and a long-read range of 15 ft. In addition, the read range for different bending angles and lifetimes of the tag antenna are also demonstrated. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Polarization Independent Quasi-TEM Metamaterial Absorber for X and Ku Band Sensing Applications
Sensors 2018, 18(12), 4209; https://doi.org/10.3390/s18124209
Received: 10 August 2018 / Revised: 4 October 2018 / Accepted: 8 October 2018 / Published: 30 November 2018
PDF Full-text (6105 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a dual-band metamaterial absorber (MMA) ring with a mirror reflexed C-shape is introduced for X and Ku band sensing applications. The proposed metamaterial consists of two square ring resonators and a mirror reflexed C-shape, which reveals two distinctive absorption bands [...] Read more.
In this paper, a dual-band metamaterial absorber (MMA) ring with a mirror reflexed C-shape is introduced for X and Ku band sensing applications. The proposed metamaterial consists of two square ring resonators and a mirror reflexed C-shape, which reveals two distinctive absorption bands in the electromagnetic wave spectrum. The mechanism of the two-band absorber particularly demonstrates two resonance frequencies and absorption was analyzed using a quasi-TEM field distribution. The absorption can be tunable by changing the size of the metallic ring in the frequency spectrum. Design and analysis of the proposed meta-absorber was performed using the finite-integration technique (FIT)-based CST microwave studio simulation software. Two specific absorption peaks value of 99.6% and 99.14% are achieved at 13.78 GHz and 15.3 GHz, respectively. The absorption results have been measured and compared with computational results. The proposed dual-band absorber has potential applications in sensing techniques for satellite communication and radar systems. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Triple-Band Dual-Sense Circularly Polarized Hybrid Dielectric Resonator Antenna
Sensors 2018, 18(11), 3899; https://doi.org/10.3390/s18113899
Received: 24 October 2018 / Revised: 9 November 2018 / Accepted: 9 November 2018 / Published: 12 November 2018
PDF Full-text (1406 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a triple-band dual-sense circularly polarized (CP) hybrid dielectric resonator antenna is proposed. A modified hexagonal dielectric resonator (DR) is top-loaded with a square microstrip ring (SMR). A vertical-tapered-strip connected to a 50-Ω microstrip line is used to excite the [...] Read more.
In this paper, a triple-band dual-sense circularly polarized (CP) hybrid dielectric resonator antenna is proposed. A modified hexagonal dielectric resonator (DR) is top-loaded with a square microstrip ring (SMR). A vertical-tapered-strip connected to a 50- Ω microstrip line is used to excite the proposed antenna. It is found that the lower and central CP bands correspond to left-handed circular polarization and are produced by the TM 11 and TE 111 modes of the SMR and modified hexagonal DR, respectively. The upper CP band is formed by the combination of the quasi-TM 21 mode of the SMR and quasi-TE 111 mode of the DR that exhibits right-handed circular polarization. The measurement results of the fabricated prototype show triple-band response for |S 11 | < −10 dB with impedance bandwidths (IBWs) of 17.4% (1.75–2.03 GHz), 28.13% (2.23–2.96 GHz), and 2.97% (3.65–3.76 GHz) in the lower, central, and upper bands, respectively. The measured 3 dB axial ratio bandwidths lying within −10 dB IBWs are 3.69% (1.86–1.93 GHz), 5.46% (2.67–2.82 GHz), and 2.15% (3.68–3.76 GHz) along with the peak gains of 5 dBic, 5.28 dBic, and 2.36 dBic in the lower, central, and upper bands, respectively. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Resonator Based Switching Technique between Ultra Wide Band (UWB) and Single/Dual Continuously Tunable-Notch Behaviors in UWB Radar for Wireless Vital Signs Monitoring
Sensors 2018, 18(10), 3330; https://doi.org/10.3390/s18103330
Received: 13 September 2018 / Revised: 28 September 2018 / Accepted: 30 September 2018 / Published: 4 October 2018
Cited by 8 | PDF Full-text (4744 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a novel resonator that can switch and create three important behaviors within the same antenna using miniaturized capacitors. The resonator was integrated into conventional Ultra-Wide Band (UWB) antenna to achieve UWB and Single/Dual continuously tunable-notch behaviors. The Single/Dual notched was [...] Read more.
This paper presents a novel resonator that can switch and create three important behaviors within the same antenna using miniaturized capacitors. The resonator was integrated into conventional Ultra-Wide Band (UWB) antenna to achieve UWB and Single/Dual continuously tunable-notch behaviors. The Single/Dual notched was continuously tuned to our desired frequency band by changing the value of the capacitors. The antenna designed and fabricated to validate these behaviors had a compact size of 24 × 30.5 mm2, including the ground plane. The radiation patterns were very clean due to the placement of the proposed resonator in the special ground plane. Moreover, the presented novel resonator and switching technique was compared with the recently proposed resonators and their switching techniques. The prototype for the antenna was also developed in order to validate its performance in wireless vital signs monitoring. The presented miniaturized resonator based antenna was utilized for tumor sensing and simulations were provided in this regard. Moreover, the deployment of the proposed resonator based UWB antenna sensor in Pipeline Integrity Monitoring system was also investigated and discussed. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring
Sensors 2018, 18(9), 3155; https://doi.org/10.3390/s18093155
Received: 1 September 2018 / Revised: 12 September 2018 / Accepted: 14 September 2018 / Published: 19 September 2018
Cited by 8 | PDF Full-text (6550 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the bandwidth enhancement and frequency scanning for fan beam array antenna utilizing novel technique of band-pass filter integration for wireless vital signs monitoring and vehicle navigation sensors. First, a fan beam array antenna comprising of a grounded coplanar waveguide (GCPW) [...] Read more.
This paper presents the bandwidth enhancement and frequency scanning for fan beam array antenna utilizing novel technique of band-pass filter integration for wireless vital signs monitoring and vehicle navigation sensors. First, a fan beam array antenna comprising of a grounded coplanar waveguide (GCPW) radiating element, CPW fed line, and the grounded reflector is introduced which operate at a frequency band of 3.30 GHz and 3.50 GHz for WiMAX (World-wide Interoperability for Microwave Access) applications. An advantageous beam pattern is generated by the combination of a CPW feed network, non-parasitic grounded reflector, and non-planar GCPW array monopole antenna. Secondly, a miniaturized wide-band bandpass filter is developed using SCSRR (Semi-Complementary Split Ring Resonator) and DGS (Defective Ground Structures) operating at 3–8 GHz frequency band. Finally, the designed filter is integrated within the frequency scanning beam array antenna in a novel way to increase the impedance bandwidth as well as frequency scanning. The new frequency beam array antenna with integrated band-pass filter operate at 2.8 GHz to 6 GHz with a wide frequency scanning from the 50 to 125-degree range. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Homogeneous Breast Phantom Measurement System with an Improved Modified Microwave Imaging Antenna Sensor
Sensors 2018, 18(9), 2962; https://doi.org/10.3390/s18092962
Received: 12 July 2018 / Revised: 30 August 2018 / Accepted: 31 August 2018 / Published: 5 September 2018
Cited by 4 | PDF Full-text (7370 KB) | HTML Full-text | XML Full-text
Abstract
Microwave breast imaging has been reported as having the most potential to become an alternative or additional tool to the existing X-ray mammography technique for detecting breast tumors. Microwave antenna sensor performance plays a significant role in microwave imaging system applications because the [...] Read more.
Microwave breast imaging has been reported as having the most potential to become an alternative or additional tool to the existing X-ray mammography technique for detecting breast tumors. Microwave antenna sensor performance plays a significant role in microwave imaging system applications because the image quality is mostly affected by the microwave antenna sensor array properties like the number of antenna sensors in the array and the size of the antenna sensors. In this paper, a new system for successful early detection of a breast tumor using a balanced slotted antipodal Vivaldi Antenna (BSAVA) sensor is presented. The designed antenna sensor has an overall dimension of 0.401λ × 0.401λ × 0.016λ at the first resonant frequency and operates between 3.01 to 11 GHz under 10 dB. The radiating fins are modified by etching three slots on both fins which increases the operating bandwidth, directionality of radiation pattern, gain and efficiency. The antenna sensor performance of both the frequency domain and time domain scenarios and high-fidelity factor with NFD is also investigated. The antenna sensor can send and receive short electromagnetic pulses in the near field with low loss, little distortion and highly directionality. A realistic homogenous breast phantom is fabricated, and a breast phantom measurement system is developed where a two antennas sensor is placed on the breast model rotated by a mechanical scanner. The tumor response was investigated by analyzing the backscattering signals and successful image construction proves that the proposed microwave antenna sensor can be a suitable candidate for a high-resolution microwave breast imaging system. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Compact Ultrawideband Antenna Based on Hexagonal Split-Ring Resonator for pH Sensor Application
Sensors 2018, 18(9), 2959; https://doi.org/10.3390/s18092959
Received: 20 July 2018 / Revised: 2 September 2018 / Accepted: 3 September 2018 / Published: 5 September 2018
Cited by 2 | PDF Full-text (12025 KB) | HTML Full-text | XML Full-text
Abstract
A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip [...] Read more.
A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip line and a split in one HSRR is introduced to increase the electrical length and coupling effect. The presented UWB antenna consists of three unit cells on top of the radiating patch element. This combination of UWB antenna and HSRR gives double-negative characteristics which increase the sensitivity of the UWB antenna for the pH sensor. The proposed ultrawideband antenna metamaterial sensor was designed and fabricated on FR-4 substrate. The electrical length of the proposed metamaterial antenna sensor is 0.238 × 0.194 × 0.016 λ, where λ is the lowest frequency of 3 GHz. The fractional bandwidth and bandwidth dimension ratio were achieved with the metamaterial-inspired antenna as 146.91% and 3183.05, respectively. The operating frequency of this antenna sensor covers the bandwidth of 17 GHz, starting from 3 to 20 GHz with a realized gain of 3.88 dB. The proposed HSRR-based ultrawideband antenna sensor is found to reach high gain and bandwidth while maintaining the smallest electrical size, a highly desired property for pH-sensing applications. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Microwave Imaging Sensor Using Low Profile Modified Stacked Type Planar Inverted F Antenna
Sensors 2018, 18(9), 2949; https://doi.org/10.3390/s18092949
Received: 9 May 2018 / Revised: 14 July 2018 / Accepted: 17 July 2018 / Published: 5 September 2018
PDF Full-text (6125 KB) | HTML Full-text | XML Full-text
Abstract
Microwave imaging is the technique to identify hidden objects from structures using electromagnetic waves that can be applied in medical diagnosis. The change of dielectric property can be detected using microwave antenna sensor, which can lead to localization of abnormality in the human [...] Read more.
Microwave imaging is the technique to identify hidden objects from structures using electromagnetic waves that can be applied in medical diagnosis. The change of dielectric property can be detected using microwave antenna sensor, which can lead to localization of abnormality in the human body. This paper presents a stacked type modified Planar Inverted F Antenna (PIFA) as microwave imaging sensor. Design and performance analysis of the sensor antenna along with computational and experimental analysis to identify concealed object has been investigated in this study. The dimension of the modified PIFA radiating patch is 40 × 20 × 10 mm3. The reflector walls used, are 45 mm in length and 0.2-mm-thick inexpensive copper sheet is considered for the simulation and fabrication which addresses the problems of high expenses in conventional patch antenna. The proposed antenna sensor operates at 1.55–1.68 GHz where the maximum realized gain is 4.5 dB with consistent unidirectional radiation characteristics. The proposed sensor antenna is used to identify tumor in a computational human tissue phantom based on reflection and transmission coefficient. Finally, an experiment has been performed to verify the antenna’s potentiality of detecting abnormality in realistic breast phantom. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Compact Multilayer Yagi-Uda Based Antenna for IoT/5G Sensors
Sensors 2018, 18(9), 2914; https://doi.org/10.3390/s18092914
Received: 27 July 2018 / Revised: 28 August 2018 / Accepted: 30 August 2018 / Published: 2 September 2018
Cited by 1 | PDF Full-text (5262 KB) | HTML Full-text | XML Full-text
Abstract
To increase the capacity and performance of communication systems, the new generation of mobile communications (5G) will use frequency bands in the mmWave region, where new challenges arise. These challenges can be partially overcome by using higher gain antennas, Multiple-Input Multiple-Output (MIMO), or [...] Read more.
To increase the capacity and performance of communication systems, the new generation of mobile communications (5G) will use frequency bands in the mmWave region, where new challenges arise. These challenges can be partially overcome by using higher gain antennas, Multiple-Input Multiple-Output (MIMO), or beamforming techniques. Yagi-Uda antennas combine high gain with low cost and reduced size, and might result in compact and efficient antennas to be used in Internet of Thins (IoT) sensors. The design of a compact multilayer Yagi for IoT sensors is presented, operating at 24 GHz, and a comparative analysis with a planar printed version is shown. The stacked prototype reveals an improvement of the antenna’s main properties, achieving 10.9 dBi, 2 dBi more than the planar structure. In addition, the multilayer antenna shows larger bandwidth than the planar; 6.9 GHz compared with 4.42 GHz. The analysis conducted acknowledges the huge potential of these stacked structures for IoT applications, as an alternative to planar implementations. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Broadband Dual-Polarized Base Station Antenna for Fifth-Generation (5G) Applications
Sensors 2018, 18(8), 2701; https://doi.org/10.3390/s18082701
Received: 26 July 2018 / Revised: 9 August 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
Cited by 1 | PDF Full-text (3209 KB) | HTML Full-text | XML Full-text
Abstract
A broadband dual-polarized base station antenna with special designed feeding structures is investigated in this paper. The proposed antenna contains two pairs of crossed dipoles, two specially designed feeding connectors, two pieces of dielectric pads, a supporter (also a balun), and a reflector. [...] Read more.
A broadband dual-polarized base station antenna with special designed feeding structures is investigated in this paper. The proposed antenna contains two pairs of crossed dipoles, two specially designed feeding connectors, two pieces of dielectric pads, a supporter (also a balun), and a reflector. To verify the designed antenna, a prototype is fabricated and measured. The antenna attains a bandwidth of around 46.5% operating over 3.14–5.04 GHz under reflection coefficient lower than −15 dB, and the port-to-port isolation is higher than 32.5 dB. It also achieves very stable radiation patterns with half power beam widths of 71.8° ± 2.5° in both the horizontal and vertical planes and gains of around 8 dBi over its operating band. Besides, the mechanism of the obtained good performances is clearly explained from the angle of current. All of the features ensure that the proposed antenna is suitable for the fifth-generation (5G) mobile communications. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A Solar Panel-Integrated Modified Planner Inverted F Antenna for Low Earth Orbit Remote Sensing Nanosatellite Communication System
Sensors 2018, 18(8), 2480; https://doi.org/10.3390/s18082480
Received: 28 June 2018 / Revised: 27 July 2018 / Accepted: 27 July 2018 / Published: 31 July 2018
PDF Full-text (6759 KB) | HTML Full-text | XML Full-text
Abstract
One of the most efficient methods to observe the impact of geographical, environmental, and geological changes is remote sensing. Nowadays, nanosatellites are being used to observe climate change using remote sensing technology. Communication between a remote sensing nanosatellite and Earth significantly depends upon [...] Read more.
One of the most efficient methods to observe the impact of geographical, environmental, and geological changes is remote sensing. Nowadays, nanosatellites are being used to observe climate change using remote sensing technology. Communication between a remote sensing nanosatellite and Earth significantly depends upon antenna systems. Body-mounted solar panels are the main source of satellite operating power unless deployable solar panels are used. Lower ultra-high frequency (UHF) nanosatellite antenna design is a crucial challenge due to the physical size constraint and the need for solar panel integration. Moreover, nanosatellite space missions are vulnerable because of antenna and solar panel deployment complexity. This paper proposes a solar panel-integrated modified planner inverted F antenna (PIFA) to mitigate these crucial limitations. The antenna consists of a slotted rectangular radiating patch with coaxial probe feeding and a rectangular ground plane. The proposed antenna has achieved a −10 dB impedance bandwidth of 6.0 MHz (447.5 MHz–453.5 MHz) with a small-sized (80 mm× 90 mm× 0.5 mm) radiating element. In addition, the antenna achieved a maximum realized gain of 0.6 dB and a total efficiency of 67.45% with the nanosatellite structure and a solar panel. The challenges addressed by the proposed antenna are to ensure solar panel placement between the radiating element and the ground plane, and provide approximately 55% open space to allow solar irradiance into the solar panel. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
A 3-D Meandered Probe-Fed Dual-Band Circularly Polarized Dielectric Resonator Antenna
Sensors 2018, 18(8), 2421; https://doi.org/10.3390/s18082421
Received: 29 June 2018 / Revised: 21 July 2018 / Accepted: 22 July 2018 / Published: 25 July 2018
Cited by 1 | PDF Full-text (623 KB) | HTML Full-text | XML Full-text
Abstract
A dual-band circularly polarized (CP) dielectric resonator antenna (DRA) designed on multi-layer substrates is proposed. An asymmetric C-shaped metallic strip is also incorporated into the upper side of the top substrate in the proposed design. The hexagonal dielectric resonator (DR) is excited by [...] Read more.
A dual-band circularly polarized (CP) dielectric resonator antenna (DRA) designed on multi-layer substrates is proposed. An asymmetric C-shaped metallic strip is also incorporated into the upper side of the top substrate in the proposed design. The hexagonal dielectric resonator (DR) is excited by the proposed 3-D meandered probe, which generates multiple orthogonal TE-modes. It is found that the lower CP band arises due to the pair of fundamental modes of the hexagonal DR. In the upper CP band, pairs of higher broadside and even modes of the hexagonal DR are combined with a CP band that is induced by the asymmetric C-shaped metallic strip to yield a wide 3 dB axial ratio bandwidth (ARBW). A prototype of the proposed DRA is fabricated for experimental verification. The antenna exhibits a measured −10 dB reflection bandwidth of 56.43% (2.15–3.84 GHz). The far-field measurement shows measured 3 dB ARBWs of 7.56% (2.29–2.47 GHz) with a peak gain of 5.6 dBic and 16.47% (3.12–3.68 GHz) with a peak gain of 7.84 dBic in the lower and upper bands, respectively. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Open AccessArticle
Microwave Metamaterial Absorber for Non-Destructive Sensing Applications of Grain
Sensors 2018, 18(6), 1912; https://doi.org/10.3390/s18061912
Received: 3 May 2018 / Revised: 1 June 2018 / Accepted: 10 June 2018 / Published: 12 June 2018
Cited by 1 | PDF Full-text (7665 KB) | HTML Full-text | XML Full-text
Abstract
In this work, we propose a metamaterial absorber at microwave frequencies with significant sensitivity and non-destructive sensing capability for grain samples. This absorber is composed of cross-resonators periodically arranged on an ultrathin substrate, a sensing layer filled with grain samples, and a metal [...] Read more.
In this work, we propose a metamaterial absorber at microwave frequencies with significant sensitivity and non-destructive sensing capability for grain samples. This absorber is composed of cross-resonators periodically arranged on an ultrathin substrate, a sensing layer filled with grain samples, and a metal ground. The cross-resonator array is fabricated using the printed circuit board process on an FR-4 board. The performance of the proposed metamaterial is demonstrated with both full-wave simulation and measurement results, and the working mechanism is revealed through multi-reflection interference theory. It can serve as a non-contact sensor for food quality control such as adulteration, variety, etc. by detecting shifts in the resonant frequencies. As a direct application, it is shown that the resonant frequency displays a significant blue shift from 7.11 GHz to 7.52 GHz when the mass fraction of stale rice in the mixture of fresh and stale rice is changed from 0% to 100%. In addition, the absorber shows a distinct difference in the resonant absorption frequency for different varieties of grain, which also makes it a candidate for a grain classification sensor. The presented scheme could open up opportunities for microwave metamaterial absorbers to be applied as efficient sensors in the non-destructive evaluation of agricultural and food product quality. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Review

Jump to: Research

Open AccessReview
Ultra-Wideband (UWB) Antenna Sensor Based Microwave Breast Imaging: A Review
Sensors 2018, 18(9), 2951; https://doi.org/10.3390/s18092951
Received: 13 June 2018 / Revised: 28 June 2018 / Accepted: 29 June 2018 / Published: 5 September 2018
Cited by 1 | PDF Full-text (3442 KB) | HTML Full-text | XML Full-text
Abstract
Globally, breast cancer is reported as a primary cause of death in women. More than 1.8 million new breast cancer cases are diagnosed every year. Because of the current limitations on clinical imaging, researchers are motivated to investigate complementary tools and alternatives to [...] Read more.
Globally, breast cancer is reported as a primary cause of death in women. More than 1.8 million new breast cancer cases are diagnosed every year. Because of the current limitations on clinical imaging, researchers are motivated to investigate complementary tools and alternatives to available techniques for detecting breast cancer in earlier stages. This article presents a review of concepts and electromagnetic techniques for microwave breast imaging. More specifically, this work reviews ultra-wideband (UWB) antenna sensors and their current applications in medical imaging, leading to breast imaging. We review the use of UWB sensor based microwave energy in various imaging applications for breast tumor related diseases, tumor detection, and breast tumor detection. In microwave imaging, the back-scattered signals radiating by sensors from a human body are analyzed for changes in the electrical properties of tissues. Tumorous cells exhibit higher dielectric constants because of their high water content. The goal of this article is to provide microwave researchers with in-depth information on electromagnetic techniques for microwave imaging sensors and describe recent developments in these techniques. Full article
(This article belongs to the Special Issue Antenna Technologies for Microwave Sensors)
Figures

Figure 1

Sensors EISSN 1424-8220 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top