Low Profile Characteristics Research Articles

A Single Layer Low Axial Ratio Circularly Polarized Planar Wide-Angle Scanning Phased Array

This paper proposes a circularly polarized planar wide-angle scanning phased array radar. The structure of the proposed array element is a windmill-type patch with an octagon-shaped series power divider. The proposed array exhibits a low axial ratio because the element has a wide 3-dB axial ratio beamwidth and the array topology uses the sequential rotation technique. Test results show that the proposed 8 × 8 uniform planar array can realize two-dimensional circularly polarized scanning from −60° to +60° in the working band of 3.43–3.48 GHz. The coverage gains of θ = ±60° are about 3 dB lower than the gain when the main beam points at θ = 0°. Moreover, in the scanning mentioned above airspace, the scanning beam axial ratio is below 0.5 dB in the xz-plane (φ = 0°) and yz-plane (φ = 90°) and below 1.4 dB in the D-plane (φ = 45°). Another notable feature is the single-layer structure, and its profile is only 0.08λ0 at the center wavelength. This good low- axial ratio and low-profile characteristics make the proposed array potentially applicable to low-orbit satellite communications.

Design and Validation of Water Based Dense Dielectric Patch Antenna (DDPA) for Microwave Communication around Frequency of 1GHz

Liquid antennas are distinct types of antennas that have been widely used due to their low profile, reconfigurable, and tunable features with steering abilities. In this paper, a low profile, high directivity, and good efficiency reconfigurable Water-Dense Dielectric Patch Antenna (DDPA) fed by the coaxial probe is presented. Distilled water becomes lossy above 1 GHZ frequency, so it is best suitable for lower-frequency applications. A thick substrate between the water patch and the ground plane is used. An impedance bandwidth of 7% with a maximum gain of 7.78 dBi, and radiation efficiency up to 71 % is obtained. This antenna can operate over the 967 to 1038 MHz band without a reduction in radiation efficiency. Simulated results are presented to validate the new design in both CST microwave studio and ANSYS HFSS which are the best simulating software for antenna designing. The comparison shows that the new antenna has a more compact size, and simpler structure, and is suitable for low-frequency applications.

Levitation force measurement and characteristics analysis of double sided high temperature superconducting thin film device

In this paper, the levitation characteristics of double sided high temperature superconducting (HTS) thin film device is proposed and measured. Based on the unique advantages such as, passive self-stable levitation, higher payload, lower energy consumption, less maintenance cost, etc., HTS-magnetic levitation (maglev) technology has been applied in the traditional fields (rail transit and energy storage fields) and novel fields (astrophysics, space station microgravity, vibration isolation fields). As the key core components, HTS device should meet the requirements of volume, weight and cost, to improve the system operation efficiency. Thus, considering the low profile, miniaturization and lightweight characteristics of the double sided YBa2Cu3O7-x (YBCO) thin film, we measured its levitation and relaxation characteristics. Meanwhile, we also designed the YBCO thin film with meander-lines, to explore the levitation characteristic evolution mechanism. It can be found from the experimental results that, the single piece of YBCO thin film with/without meander-lines can offer the levitation force more than 400 mN and 800 mN, respectively. The signature of this work is that the double sided YBCO thin film has the potential to be employed as the core device in the special application fields (such as astrophysics and space station), to supply the sufficient micro levitation force in limited volume and weight.

A low-profile flower-shaped MIMO antenna for wireless applications

ABSTRACT A low-profile, compact and efficient antenna is especially desirable for wireless applications, as it can reduce the size and weight of the system and improve its performance. In recent years, flower-shaped antennas have gained popularity due to their low profile, broad bandwidth and good radiation characteristics. In this work, a high-isolated dual-element UWB-MIMO antenna is experimentally verified having size of 32 × 39 × 0.8 mm3. The main radiating element of MIMO setup comprises a Half-Cut Flower-Shaped (HCFS) resonator. A tree-shaped decoupling structure is use to enhance the isolation. The simulated operating band of the proposed 2-port UWB-MIMO antenna ranges from 2.3 to 2.68 GHz and 3.15 to 12.87 GHz which covers Bluetooth, Wi-Fi/WLAN, Wi-MAX and UWB) with inter-element isolation of more than 15 dB and 20 dB, respectively. The measured results are found in close agreement with simulated ones. Furthermore, the diversity parameters such as Envelope Correlation Coefficient (ECC), Channel Capacity Loss (CCL), Mean Effective Gain (MEG), Effective Diversity Gain (EDG) and Total Active Reflection Coefficient (TARC) have also been analysed to ensure its legitimacy for wireless applications. Moreover, the simulation S-parameters characteristic of the proposed 8-element antenna for wireless access point applications has also been showcased.

Ultrawideband Strip-Loaded Slotted Circular Patch Antenna Array for Millimeter-Wave Applications

A novel ultra-wideband millimeter wave (mmWave) slotted circular patch antenna and array are proposed in this paper, where each circular patch antenna element is loaded with three pairs of folded strips for enhancing the bandwidth and fed by a substrate integrated waveguide (SIW) through a coupling slot. As a result, a multimode antenna element with the ultra-wideband characteristic can be realized and the impedance fractional bandwidth (FBW) with | <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> |< -10 dB is up to 66.9%. Furthermore, an 8×8 antenna array prototype is designed and fabricated. Measured impedance FBW with | <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> |< -10 dB of 56% and measured average radiation efficiency of 73.8% are achieved. With the wideband and low-profile features, this antenna can be a promising candidate for mmWave communications.

IoT enabled vehicle recognition system using inkjet-printed windshield tag and 5G cloud network

An IoT-enabled vehicle recognition system is developed and tested in this work, besides the tag antenna design and prototype for the vehicle windshield. Firstly, a flexible, surface-tolerant, low-profile, and low-cost passive UHF-RFID windshield tag inlay is designed. The tag is prototyped as wet-inlay with silver conductive-ink inkjet printed antenna on Polyethylene-Terephthalate layer, bonded with Higgs-EC IC. The dimension of the antenna is 0.25 × 0.05λ0. The overall inlay structure is around 0.27 × 0.06λ0. The antenna is designed at ETSI band, with a return loss of −14 dB at 900 MHz and a read range of 13.3 m and 8 m over lower and upper bands, respectively. The antenna demonstrates an omnidirectional radiation pattern and a maximum gain of 1.92 dBi. The developed prototype is tested in both indoor and outdoor environments. Secondly, the data is sent over the IoT cloud where decision-making is made for authorization. The reader data is transmitted over MQTT broker, via the Scotland 5G network to the MongoDB database using Python module Pymongo. The algorithm for vehicle recognition is written and verified by testing the dummy registered tags for access authorization, with a 100% recognition accuracy. We achieved higher read ranges, surface tolerance, and low profile features, comparatively. The overall system shows optimally great results.

Design and Analysis of Fractal-Shaped High-Impedance Surface Unit Cell Characteristics

Fractal geometries consistently provide solutions to several electromagnetic design problems. In this paper, fractal geometries such as Hilbert and Moore curves are used to design efficient High-Impedance Surfaces. Modern communication devices have many sensors that are needed to communicate wirelessly. The critical component of wireless communications is antennas. Planar microstrip patch antennas are popular due to their low profile, compactness, and good radiation characteristics. The structural disadvantages of microstrip antennas are that they have surface waves that propagate over the ground plane. High-Impedance Surface (HIS) planes are a prominent solution to minimize and eliminate surface waves. The HIS structures behave as active LC filters that suppress surface waves at their resonance frequency. The resonance frequency of the structure is obtained by its LC equivalent or by analyzing the reflection phase characteristics. This work presents conventional HIS structures similar to mushroom HIS and fractal HIS such as Hilbert curve and Moore curve HIS. The HIS reflection phase characteristics are obtained by applying periodic boundary conditions with plane wave illumination. The results were obtained in terms of the reflection phase angle. The conventional mushroom structures show narrow band characteristics at given dimensions of 10 mm × 10 mm and 20 mm × 20 mm. These structures are helpful in the replacement of PEC ground planes for patch antennas under sub-6 GHz. The Hilbert and Moore fractals are also designed and have a multiband response that can be useful for L, S, and C band applications. Another design challenge of HIS is protrusions, which make design difficult. The work also presents the effect of having vias and the absence of vias on reflection phase characteristics. The response shows the least and no significant effect of vias under the x-band operation.

A Circularly Polarized Patch Antenna Array with Reduced Mutual Coupling Using the Aperture-Loading Decoupling Technique

An aperture-loaded decoupling strategy for 1 × 8 circularly polarized (CP) patch antenna array is presented in this article. By introducing an additional coupling path, the mutual coupling between adjacent antennas is cancelled. The result shows that more than 20-dB isolation enhancement is obtained by applying this strategy at the center frequency of 3.38 GHz. Mutual coupling between both adjacent and non-adjacent elements are suppressed to less than -25 dB. Moreover, the impedance bandwidth and axial ratio (AR) is also improved with decoupling. Compared with conventional CP antenna decoupling methods, the proposed approach has the characteristics of low profile, compact size, and low impact for the ground plane. It is shown that the AR bandwidth can be enhanced using the proposed decoupling method.

1-Bit Hexagonal Meander-Shaped Wideband Electronically Reconfigurable Transmitarray for Satellite Communications

This paper proposes a hexagonal meander-shaped wideband electronically reconfigurable transmitarray (HMRTA) at Ku band for satellite communications and radar applications. The proposed transmitarray offers high gain, low profile, and wideband characteristics with beam-scanning and beam-forming features. The cascaded structure is a low-profile and compact transmitarray. The transmitter (Tx) layer has an angular hexagonal patch with a meandered shape and resonating parasitic patches to enhance the bandwidth. The receiver (Rx) layer comprises a two-part hexagonal receiver patch and a dual ring impedance-matching receiver layer. The current reversal phenomena have executed the 180° phase shift by integrating two diodes in opposite directions. The measured results of a unit cell achieve a minimum insertion loss of 0.86 dB and 0.92 dB for state I and state II. The maximum insertion loss is 2.58 dB from 14.12 GHz to 18.02 GHz and is about 24.83% at 16.5 GHz. The full-wave simulations of a 20 × 20 space-fed reconfigurable transmitarray were performed. Good radiation patterns at all scanning angles of two principal planes are achieved, and the cross-polarization level remains less than −20 dB. The simulated 3 dB gain fluctuation bandwidth of the array is 15.85~18.35 GHz, and the wideband characteristics are verified. The simulation results show that the array can perform beam scanning ±60° in the elevation (y-z) plane and obtain the beam-scanning characteristics for ±60° in the Azimuth (x-z) plane.

Short review on hydroxyapatite powder coating for SS 316L

Medical implants and other biomaterials are used by millions of individuals all over the globe to restore lost bodily functions due to injury or illness. Many of these implants fail after a short time or have difficulties, despite the fact that they play important roles in keeping a person's life safe or increasing the quality of their lives. It is the lack of biocompatibility that has proven to be the biggest downfall of biomaterials. Investments in this industry may be made using a thin film of hydroxyapatite powder (HAP) on stainless steel. Plates, screws, pins, and artificial joints are only some fixation devices for bones that often use 316L stainless steel. However, due to its unique advan­tageous qualities such as super-elasticity and low-profile feature, thin film HAP signals a high potential for use in compact new cardiac devices like the cardiovascular system and protecting stent grafts.

Highly Integrated Multifunctional Antenna for Global Navigation Satellite System

This communication proposes a new highly integrated multifunctional global navigation satellite system (GNSS) antenna used for navigation or surveying high-precision area, the fourth-generation (4G) mobile communication, and short-distance wireless communication. The antenna consists of four elements, saying: 1) a low-profile navigation element on one substrate covering all the GNSS bands and 2) two long-term evolution multiple-input–multiple-output (LTE-MIMO) elements and one Wi-Fi element uniformly distributed on the edge of the substrate. This symmetrical configuration ensures the navigation element’s low axial ratio (AR) and radiation pattern symmetry, as well as navigation accuracy. In addition, to enhance the isolation between the GNSS element and other three elements under high integration, these three elements are designed to avoid resonating within the GNSS bands. The measured peak gains of the GNSS element are 6.0 dBi from 1.16 to 1.28 GHz and 6.5 dBi from 1.52 to 1.62 GHz. The −6 dB impedance bandwidth of the LTE-MIMO elements can cover 840–960, 1800–2200, and 2500–2700 MHz. The distance communication of the Wi-Fi element is 80 m. The experimental results indicate that the proposed multifunctional antenna features low profile, high integration, and wideband, implying potential application in the multifunctional satellite navigation system.

A 3D-Printed DRA Shared-Aperture Array for Low Cost Millimeter-Wave Applications

In this article, a K-/Ka-band shared-aperture array with high isolation is proposed using 3D-printed dielectric resonator antennas (DRAs). The design procedure with DRAs enables flexibility while implementing shared-aperture arrays. Furthermore, DRAs as nonmetallic radiators are attractive for millimeter-wave (mm-wave) applications due to the absence of ohmic loss. In addition, 3D-printing technology facilitates the design of complex shapes with high-dimensional accuracy. The K- and Ka-bands DRAs are orthogonally oriented to provide improved isolation and cross-polarization level. Meanwhile, the corresponding feeding networks are implemented using the substrate integrated coaxial line (SICL) and the substrate integrated waveguide (SIW). Thus, further isolation improvement is provided by using two different feeding mechanisms for the K- and Ka-bands radiators. Moreover, the SICL network is shared with the SIW wall to efficiently utilize the feeding aperture. As a proof-of-concept, the 3D-printed shared DRAs are designed and fabricated. The standard printed circuit board (PCB) technology is used for the fabrication of the antenna boards. The measurement data agree with the simulations, realizing high isolation and cross-polarization level. The proposed array features low profile, ease of integration, and wideband operation, which makes it viable candidate for mm-wave applications.

Low-Profile Dual-Wideband Dual-Polarized Antenna for 5G Millimeter-Wave Communications

This letter presents a dual-wideband dual-polarized antenna that fully covers the fifth-generation (5G) millimeter-wave (mm-wave) bands of n257−n261 (24.25–29.5 GHz and 37–43.5 GHz), and that shows a low-profile feature and a band-stop filtering response. For each polarization, the low-band and high-band radiation modes are, respectively, achieved by the two pairs of U-shaped dipole arms which are distributed along the co- and cross-polarized directions. Meanwhile, a radiation null is generated by the radiating cancellation effect of the two pairs of dipole arms, suppressing the unwanted frequency between the two operating bands. Moreover, an extra high-band resonant mode is introduced by the parasitic patches, enhancing the bandwidth of the proposed antenna. Furthermore, a vertical balun structure connecting each dipole arm with the ground is bent to reduce the antenna profile. In the fabrication, high-density interconnect printed circuit board process is employed to meet the antenna-in-package consideration. Under the constrained substrate thickness of 1 mm, the proposed antenna achieves a dual-wideband operation of 24–30 GHz (22%) and 37–43.5 GHz (16%). These merits make the proposed antenna suitable for 5G mm-wave communications.

A High-Efficiency Microstrip Antenna Pair with Similar Pi-Shaped Decoupling Structure for 3.5 GHz 5G Ultrathin Smartphones

In this paper, a low profile and high-efficiency decoupling antenna pair for multiunit smartphones is proposed using a similar π-shaped feed structure that can excite the dipole radiation mode of microstrip antenna. Ordinarily, symmetrical single-port T-shaped microstrip antennas can only excite monopole modes of bilateral radiation. This paper changes the vertical feeding microstrip structure into two oblique, similar π-shaped feeding structures. This oblique feeding structure can excite the dipole mode of unilateral radiation of the microstrip antenna. Using this method, the antenna design can be simplified, and the low-coupling independent radiation on both sides of the microstrip antenna can be freely controlled without the need for additional structures. Considering the ultra-thin characteristics of 5G smartphone devices, the parameters of the antenna are further optimized: the optimized antenna profile is only 3.7 mm. The measured results show that the 2 × 2 microstrip antenna pairs can effectively cover the 3.5 GHz band (3.4–3.6 GHz), with a coupling that varies from −16.14 dB to −11.01 dB and an efficiency that varies from 80% to 94.1%. The 8 × 8 MIMO smartphone antenna results show that the coupling varies from −20.1 dB to −12.17 dB, the efficiency varies from 79.72% to 93.7%, and the envelope correlation coefficient (ECC) is lower than 0.05. The microstrip antenna decoupling pair with a similar π-shaped feed structure proposed in this paper has high efficiency and low-profile characteristics have important application value in the decoupling design of 3.5 GHz 5G ultra-thin smartphone antennas.

A High-Efficiency Dual-Band Self-Filtering Antenna Based on Three Dense Dielectric Strip Resonators

A high-efficiency dual-band dielectric filtering antenna based on three parallel placed dense dielectric strip resonators (DDSRs) is proposed for the self-filtering property. That means both the filtering responses of the two bands are only determined by the three DDSRs themselves without extra filtering circuits. The even-mode coupling of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1δ</sub> mode (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3δ</sub> mode) between the middle and two-sided DDSRs is used to form the first (second) radiation band, while the odd-mode coupling contributes one radiation null at the upper edge of each radiation band. Therefore, the proposed dual-band dielectric antenna exhibits relatively high total efficiency benefited from the self-filtering characteristic. Additionally, the presented one without extra filtering circuits obtains the features of low profile, enhanced bandwidth, and gain. For test and verify, a prototype was measured at 7.7 and 13.35 GHz with the fractional bandwidths of 11.4% and 4.8%, the peak gains of 7.65 and 10.5 dBi, and the total efficiencies of 89% and 87%, respectively. Radiation nulls are generated at 8.5 and 13.8 GHz, respectively.

High gain low-cost antenna based on the utilization of diffracted fields from semi-ring shape dielectric edges

A simple antenna with a 20-dBi gain is proposed. A thorough analysis of the propagation mechanism accompanied by a unique physical insight is provided. The realized structure has a low profile, low-cost, and compact features. A detailed insight into applying the Fresnel–Huygens principle is provided.

A miniaturized wideband wearable antenna with circular polarization for medical application

This paper presents a wearable antenna for medical application with circular polarization, high Gain, and low-profile features. The proposed antenna is fabricated on a low loss, low weight, and completely flexible substrate to ensure antenna performance in realistic conditions. Using the frequency selective surface to beamforming the radiation pattern in different frequencies is employed to implement the antenna in on- and off-body scenarios. This novel idea keeps the SAR limit consideration and dual-mode operation at the same time for a wide range of frequencies. The antenna has an overall dimension of 20.7 × 20.5 × 0.1 mm3 and provides more than 75% measured bandwidth around the 2.4 GHz ISM band with a maximum circular gain better than 7.9 dB. The proposed antenna can operate, as an interface, simultaneously for on- and off-body applications with sharing frequency techniques. Measurement results with the phantom model show a good agreement with the simulation in different scenarios.

Multifunctional Coding Metasurface With Left and Right Circularly Polarized and Multiple Beams

In this paper, a multifunctional coding metasurface (MCMS) has been proposed to realize dual-circularly polarized beams and beam focusing with transmission and reflection. The phase of transmissive wave is controlled by rotating the elements, and the corresponding element, which consists of two quadrate voids etched on a single layer substrate, is designed for the metasurface with Pancharatnam-Berry (PB) phase. The phase distribution of the circularly polarized four-beam is determined according to the convolution theorem of patterns and the phase compensation principle. In order to validate the proposed metasurface, the multifunctional meta-device is fabricated and measured to illustrate the four-beam with left circular polarization in transmissive space and the right circularly polarized four-beam in reflective space by MCMS with x-polarized incidence. The experimental results heavily agree with the simulated data. The MCMS has potential applications in wireless communications due to its low profile, compact, and lightweight features.

Shaped-Pattern Reflectarray Antennas for mm-Wave Networks Using a Simple Cell Topology

In this paper, it is proposed the use of ultra-thin reflectarrays in some emerging scenarios in the new mm-wave cellular networks such as 5G, Beyond-5G (B5G), and future 6G. To that purpose, two dual-linear polarization reflectarrays are developed to provide coverages in different scenarios at the mm-waves band. Working at 28 GHz, reflectarray designs adapt the radiated field to the coverage area specified in each scenario, through an ultra-thin surface composed of simple cells. To evaluate the antenna performance, two reflectarray prototypes identical in size are manufactured and tested achieving a good trade-off between the performance and the low-cost, low losses and, low-profile characteristics of the antenna. This work demonstrates the good performance of simple topology reflectarrays, being an interesting antenna candidate in the upcoming wireless networks.

A filtering antenna with wide out‐of‐band suppression based on open‐stubs resonator

In this paper, a wide out-of-band suppression antenna with simple structure, low profile and filtering characteristics is presented. In order to improve the selectivity of the passband edge, two simple structures, namely U-shaped slot and two slits, are introduced into the antenna to generate radiation nulls. To obtain a wide out-of-band suppression, the feeder with π-shape stub is applied. The transmission nulls generated by the feeder are used to suppress stopband harmonics. In addition, a pair of parallel strips is introduced to enhance the gain suppression effect at the upper stopband. The measured results show that the average gain is 7 dBi, and the stopband suppression reaches 2.84 f0 (f0 is the center frequency of the proposed antenna). The overall height of the presented antenna is 0.03 λ0 (λ0 is the wavelength at the center frequency).