Integrated Microstrip Antenna Research Articles

Integrated Microstrip Antenna Reflector Based on SIW for 5G Networks

High data rates, low latency, and low energy consumption are required for the fifth-generation (5G) mobile wireless network. One of the devices that garner interest to be developed is the antenna. Microstrip antennas are widely used in cellular communications because of their simple profile and easy fabrication. However, it has limitations in terms of performance. The millimeter-wave band has been selected to provide high-speed service in 5G wireless networks. Compared to other frequency bands, the propagation path in millimeter-wave is significantly decreased. The substrate integrated waveguide (SIW) technology aims to integrate all components on the same substrate, with low insertion loss and a low profile. Using a dielectric substrate on top and a metallic coating at the bottom with metalized holes, the SIW structure offers a compact form factor for integrating active circuits, passive components, and radiation elements within the same substrate. Therefore, this study aims to design and implement a reflector integrated microstrip antenna with a compact form and a working frequency of 26 GHz. The measurements showed the return loss value of -11 dB, voltage standing wave ratio (VSWR) of 1.9, and the antenna impedance of 63 Ω. The antenna that was designed and fabricated in this work is suitable for operation in the millimeter-wave range for 5G technology.

Compact and Integrated Microstrip Antenna Modules for mm-Wave and Microwave Bands Applications

This paper presents two different antenna modules at two different bands with a compact size structure that is used for both of mm-Wave and microwave bands, with the objective of keeping the size as minimum as possible. The presented structure consists of two integrated modules with overall dimensions of 24 <inline-formula> <tex-math notation="LaTeX">$\times 15\times0.787$ </tex-math></inline-formula> mm³ and is implemented on a Rogers RT5880 substrate. The first module is designed to resonate at 25.75 GHz with bandwidth of 4.15 GHz. The length of this module is taken as a constraint in designing the second module, which is the microwave one. This module is designed to have resonance frequency of 5.45 GHz with bandwidth of 1.12 GHz. The two modules are etched on the same substrate in an integrated fashion to give the required structure with two separate feeds and a separation gap between them in the ground plane. The proposed antenna structure is simulated using the CST-MW studio simulator, where it is found that for the mm-Wave module, the band&#x2019;s gain is 5.58 dBi and the efficiency is 0.87 at 25.75 GHz. As for the microwave module, the gain is 2.45 dBi and the efficiency is 0.77 at 5.45 GHz. The proposed structure is implemented practically and the relevant measures agree with the simulated ones. A comparison of the proposed structure with other designs available in literature shows that it exhibits the minimum size among them, while keeping the other parameter values of comparable orders. The proposed structure is suitable for being used in 5G applications where both of the microwave and millimeter- wave bands are utilized.

Three-dimensional woven structural glass fiber/polytetrafluoroethylene (PTFE) composite antenna with superb integrity and electromagnetic performance

Integration of electronic devices into composites is imperative for the development of smart structural materials, which can address the structure limitations, such as the delamination of structures and degradation of electronic performances. In this study, the 3D orthogonal woven composite antenna (3DIMA) based on glass fiber and PTFE polymer were manufactured for the first time by multiple impregnation and sintering processes to obtain adequate PTFE penetration and good mechanical properties. Consequently, the as-produced 3D integrated microstrip antenna (3DIMA) showed good mechanical properties (bending, compression, impact strength) and electromagnetic performance with proper radiation pattern as well as gain value (1.3 dB), showing similar performance with conventional microstrip antenna. Besides, the simulated return losses and radiation patterns obtained from professional antenna software agreed well with the tested results. Furthermore, the 3DIMA maintained similar radiation pattern even under the low velocity impact with the kenitic engery of 15 J, exhibiting excellent structural integrity.

Passive FSS based polarization converter integrated microstrip antenna

A reflection mode linear to circular polarization converter (PC) with high angular stability up to 60° is proposed in which no metallic backing is required, like the conventional PCs. Two distinct frequency selective surfaces (FSS1 and FSS2) are designed to block TE and TM waves, respectively, across the same frequency band (6.8–13.6 GHz). While the top layer (FSS1) and bottom layer (FSS2) are kept at an air gap of λ/8 between them, a phase quadrature in orthogonal components of the reflected wave is realized. An axial ratio ≤ 3 dB is obtained by designing the FSS layers such that the magnitude of reflection coefficient (S11) under TM polarization for FSS2 is equal to that of FSS1 under TE polarization. As a proof of concept, this PC is integrated with a linearly polarized (LP) microstrip antenna (MSA) and tested. It converts the LP waves into circularly polarized (CP) waves at three different frequency bands and also enhances antenna gain by 4.5 dB. Further, by varying only the altitudinal position of the top FSS layer manually, reconfigurability in CP bands can be accomplished without using any active elements and electronic tuning systems. A prototype is fabricated and validated by proper measurements.

Microfluidic Flexible Substrate Integrated Microstrip Antenna Sensor for Sensing of Moisture Content in Lubricating Oil

In this paper, a flexible microstrip patch antenna sensor is proposed for monitoring of the moisture content of lubricating oil. The sensor identifies liquids having different effective dielectric constants by detecting changes in the resonance frequency. The proposed antenna comprises a radiation patch, a metal ground plane, and a PDMS substrate with microchannels. The microchannels are etched on the PDMS substrate. When the relative permittivity of the microfluidic channel is 1.8∼12.5, the operating frequency of the proposed antenna changes from 2.230 to 2.116 GHz, and the amplitude of the reflection coefficient is greater than −26.3 dB. The simulation and measurement results show that the proposed sensor can monitor the lubricating oil with different moisture contents, which can cause frequency separation of at least 20 MHz and achieve a good linear response. Therefore, the proposed sensor has the feasibility of monitoring the quality of lubricating oil.

Co-Design of a GPS Antenna Low-Noise Amplifier Front-End Circuit

This paper presents a clear and fast design procedure for directly matched low noise active integrated microstrip antenna front end circuits. Initially, a theoretical analysis is given for the overall gain equivalence between traditional and directly matched antennas. Then, a detailed procedure is presented for the design and construction of a fully integrated GPS antenna. To validate the proposed procedure, a prototype was built and characterized by measuring the reflection coefficient, radiation pattern, noise figure and the active antenna overall gain. Additionally, a field test comparison was made between the manufactured prototype and a commercially available active antenna using the u-blox NEO-6M GPS receiver module. The prototype experimental and field test results showed excellent performance, thus validating the proposed co-design approach.

A printable trapezoid-structured UWB micro-strip antenna applicable to MEMS wireless sensor networks

This paper comprises of two related works. Firstly, a printable trapezoid-structured UWB micro-strip antenna applicable to MEMS wireless sensor networks (WSN) is proposed from the view point of both the return loss and the impedance bandwidth. A dimensionless parameter, defined as the width ratio of the top edge to the bottom edge of the proposed trapezoid-structure, is introduced to explore the relevance between the trapezoidal geometry and the S11 curve. An optimized trapezoidal structure with better S11 curve is achieved and expected to have various WSN applications. Secondly, a wireless electric current sensor via integrating a magnetic piezoelectric cantilever and the optimized trapezoidal-structured micro-strip antenna is presented for the first time to show the applicability to WSN preliminarily. The wireless current sensor system, consisting of both the magnetic piezoelectric cantilever for measuring electric currents and the trapezoidal-structural micro-strip antenna for transmitting output voltages, are designed and integrated for demonstration, at an operating frequency of 3 GHz with the lowest return loss. Although output errors of 2–7% are observed for output voltage range of 88–116 mV, the signal transmission measurement demonstrates that the proposed integration is experimentally feasible and effective. Due to the ultra-wideband (2–11 GHz) and low power consumption of the integrated micro-strip antenna, the proposed integration is expected to be applicable to various kinds of wireless sensor nodes of different frequencies or multi-sensors monitoring systems.

Wireless electric current sensing via integrating a magnetic–piezoelectric cantilever with a microstrip antenna

This work for the first time presents a wireless electric current sensor via integrating a magnetic-piezoelectric cantilever and a trapezoidal-structured microstrip antenna. The wireless current sensor system, consisting of both the magnetic-piezoelectric cantilever for measuring electric currents and the trapezoidal-structured microstrip antenna for transmitting output voltages, are designed and integrated for demonstration, at an operating frequency of 3 GHz with the lowest return loss. Although output errors of 2-7% are observed for output voltage range of 88-116 mV, the signal transmission measurement demonstrates that the proposed integration is experimentally feasible and effective. Owing to the ultra-wideband (2-11 GHz) and low-power consumption of the integrated microstrip antenna, the proposed integration is expected to be applicable to various kinds of wireless sensor nodes of different frequencies or multi-sensors monitoring systems.

Effects of weaving structures and parameters on the radiation properties of three-dimensional fabric integrated microstrip antennas

In smart textile systems, the wireless communication between the wearer and the wider environment plays an important role, especially in medical applications. This can be achieved by integrating an antenna in textile materials. The low-profile microstrip antenna is a desirable choice for textile antennas and integrating this type of antenna into the three-dimensional woven fabric achieves the most integrated textile antenna structure up to now. Different from traditional antenna structures, the three-dimensional woven fabric integrated microstrip antenna has the radiation patch and ground plane totally woven with the yarns, where the radiation properties would strongly depend on the weaving structures and parameters. In this paper, a 1.9 GHz single patch microstrip antenna was designed and six types of antennas with different combinations of woven patches and ground planes were compared. The measured results showed that the three-dimensional woven antenna had adequate performance. In addition, the three-dimensional woven antenna with warp yarns parallel to the feeding direction exhibited a better return loss and radiation pattern than the antenna with weft yarn parallel to the feeding direction, due to the longer current path for the latter antenna based on simulated current distribution analysis. Furthermore, the effects of conductive yarn parameters on the antenna properties were discussed and yarn structures were suggested to obtain relatively ideal antenna performances.

Electromagnetic performance and impact damage of the microstrip antennas integrated in cylindrical three dimensional woven composite structures

A three dimensional integrated microstrip antenna (3DIMA) is a novel multifunctional structure, which can perform as a load bearing structure and function as an antenna. In this study, a single‐element and a double‐element microstrip antenna were integrated into cylindrical three‐dimensional woven glass fiber/epoxy composites respectively. Their electromagnetic performance and impact damage were investigated. The results showed that with the decrease of the curvature radii from 75 to 25 mm, the single‐element 3DIMAs with the feed direction perpendicular to the curvature showed more stable resonant frequencies and gain values than those of 3DIMAs with the feed direction parallel to the curvature. While the opposite results were observed for the double‐element 3DIMAs. The double‐element cylindrical 3DIMAs with the feed direction parallel to the curvature showed the best voltage standing wave ratios (VSWR &lt; 1.25), resonant frequencies (near 1.5 GHz), gains (from 2.37 to 1.44 dB) and reasonable radiation pattern properties. In addition, impact tests were conducted with the impact energies ranging from 0 to 20 J. The results showed that the VSWRs slightly changed, demonstrating good impact resistance, and structural integrity of cylindrical 3DIMA structure. POLYM. COMPOS., 39:3259–3267, 2018. © 2017 Society of Plastics Engineers

Cross type defected ground structure integrated microstrip antenna: a novel perspective for broad banding and augmenting polarization purity

A simple cross type defected ground structure (CDGS) integrated rectangular microstrip antenna (RMA) has been proposed to achieve broad bandwidth along with augmented (improved) co-polarized to cross-polarized radiation (CP-XP) isolation over principal and diagonal planes. In this design, a crucial emphasis is given for concurrent improvement of both bandwidth and polarization purity of microstrip antenna without hampering dominant mode fields. Around 25–28 dB CP-XP isolation is achieved over wide elevation angle with the proposed structure with 25% impedance bandwidth. The simulated and measured results show a close resemblance with each other. The proposed geometry is very simple, easy to fabricate and therefore helps in effortlessness manufacturing process. Therefore, the present structure appears to be ideal in numerous applications where polarization purity is the key issue over the wide bandwidth.

Integrated Microstrip Antennas and Phased Arrays with Mode-Free Electromagnetic Bandgap Materials for Scan Blindness Elimination

ABSTRACTThis article discusses the investigation of the use of mode-free electromagnetic bandgap materials, a novel bandgap-antenna structure, to eliminate scan blindness from two-dimensional infinite microstrip phased arrays. This electromagnetic bandgap material is multi-functional; in addition to suppressing both surface and leaky waves, it also radiates to broadside direction as an antenna element within the mode-free bandgap region. A strip line impedance matching network is used to match the bandgap-antenna element’s input impedance to 50 Ω, so that the actual bandgap behavior of the structure on the array can be obtained since the strip line does not allow couplings within the matching network. In addition, internal couplings within the unit element of the bandgap-antenna structure, which is composed of four metallic layers, are analyzed in detail; these internal couplings vary with array element’s excitation phase or scan angles, therefore, an optimum structure must consider scan behavior as well.

Circularly polarized strips integrated microstrip antenna for energy harvesting applications

ABSTRACTA circularly polarized (CP) microstrip antenna with four strips is proposed for wide beamwidth and RF energy harvesting applications. Four strips along the diagonal directions are integrated symmetrically onto a square patch radiator for CP radiation with wide beamwidth. To improve the impedance matching of the antenna, a stub is integrated along the orthogonal direction of the patch radiator. The antenna is designed on FR4 substrate and an antenna prototype shows a measured 10‐dB return loss bandwidth of 120 MHz (2.53–2.65 GHz) with a maximum gain of 4.6 dBic. The measured 3‐dB axial ratio (AR) bandwidth is 65 MHz (2.540–2.605 GHz) with a 3‐dB AR beamwidth of around 180° across the band. Overall antenna volume is 0.475λo× 0.475λo × 0.013λo at 2.5 GHz. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1044–1049, 2016

Antenna-resonator integrated wireless passive temperature sensor based on low-temperature co-fired ceramic for harsh environment

This paper proposes a resonator-antenna integrated microstrip antenna temperature sensor based on a low-temperature co-fired ceramic (LTCC), whose permittivity varies monotonously with the temperature. The dimensional design process was first analyzed in detail, and by combining the standard LTCC technology, the sensor was fabricated using 15 layers of a green tape. To interrogate the sensor, a coplanar waveguide (CPW)-fed microstrip antenna, possessing a relatively large bandwidth, was designed and optimized using high frequency structure simulator software, and then fabricated on alumina ceramic through a screen-printing process. The sensor was then tested on a developed high-temperature measurement system. Because the original detected sweep signal was difficult to distinguish, a time-domain (T-D) gating method for filtering a background signal was introduced. The extracted peak frequency was found to decrease linearly with an increase in temperature to within 400°C at a 30-mm reading distance, with a measurement sensitivity of 0.24MHz/°C. Simultaneously, the antenna polarity was found to have a significant influence on the readout signal. Finally, for the introduced T-D gating method, this study analyzes that the sensor can be sensed at a long distance when using a high-gain interrogation antenna. It is expected that the proposed sensor can be used in monitoring the temperature in a harsh environment.

Simulation and electromagnetic performance of cylindrical two-element microstrip antenna array integrated in 3D woven glass fiber/epoxy composites

Three dimensional integrated microstrip antennas (3DIMA) can carry substantial external load while functioning as antennas. In this study, cylindrical two-element antennas integrated in three dimensional orthogonal woven glass fiber/epoxy composites with various curvatures are fabricated. The effects of the cylindrical curvature on the electromagnetic performance of the 3DIMAs are simulated using High Frequency Structural Simulator and verified experimentally. The results show that all cylindrical 3DIMAs, with different radii of curvature, namely 75, 60, and 45mm, exhibit utility return losses of −20dB. However, their resonant frequencies and gains are significantly influenced by the curvature as well as the arrangement of the curvature and feeding directions. When the curvature of the cylindrical structure was along the feeding direction of the antenna, the 3DIMAs showed more stable resonant frequencies (around 1.5GHz), gain values (from 2.37dB to 1.44dB) and proper radiation patterns, compared with the antenna with the curvature perpendicular to the feeding direction.

Design of reconfigurable active integrated microstrip antenna with switchable low‐noise amplifier/power amplifier performances for wireless local area network and WiMAX applications

A novel design of reconfigurable monopole microstrip active integrated antenna (AIA) for wireless local area network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) applications is presented and discussed in this study. The primary designed reconfigurable passive antenna is capable of supporting switchable single/dual band performances while having a compact dimension of 12 × 18 mm2. The proposed reconfigurable passive antenna is integrated with an interdigital filter and a reconfigurable switchable power/low-noise amplifier (LNA) (power amplifier – PA, LNA) forming a single-port microstrip AIA which can be used as a full-duplex switchable transceiver in which the need for additional filters is eliminated because of its reconfigurable structure. A 2.3–2.56 GHz (WLAN) with 12.3 dB (PA) gain improvement and 3.3–3.59 GHz (WiMAX) with 8.5 dB (LNA) gain improvement are supported at switchable performances of the fabricated reconfigurable AIA. Measured results show that the designed passive and active antennas have proper almost omnidirectional radiation characteristics at their desired operation frequencies which is suitable for WLAN and WiMAX applications.

Cylindrical conformal single-patch microstrip antennas based on three dimensional woven glass fiber/epoxy resin composites

Three dimensional integrated microstrip antenna (3DIMA) can carry the designed load while functioning as an antenna. In this study, the cylindrical conformal single-patch 3DIMAs with various curvatures were designed, simulated, fabricated and tested experimentally using a 3D orthogonal woven glass preform/epoxy resin composite system. The electromagnetic performances of the cylindrical microstrip antennas were analyzed. The simulated and tested results matched well and the return losses of the cylindrical conformal 3DIMAs with radii of curvatures of 60, 45 and 25 mm were less than −10 dB while resonant frequencies and their gain values were significantly influenced by the radius of curvature and the feeding direction. The 3DIMAs with the curvature perpendicular to the feeding directions showed more stable resonant frequencies and larger gain values than those of 3DIMAs with the curvature along their feeding directions.

Effect of Weaving Direction of Conductive Yarns on Electromagnetic Performance of 3D Integrated Microstrip Antenna

A three-dimensionally integrated microstrip antenna (3DIMA) is a microstrip antenna woven into the three-dimensional woven composite for load bearing while functioning as an antenna. In this study, the effect of weaving direction of conductive yarns on electromagnetic performance of 3DIMAs are investigated by designing, simulating and experimental testing of two microstrip antennas with different weaving directions of conductive yarns: one has the conductive yarns along the antenna feeding direction (3DIMA-Exp1) and the other has the conductive yarns perpendicular the antenna feeding direction (3DIMA-Exp2). The measured voltage standing wave ratio (VSWR) of 3DIMA-Exp1 was 1.4 at the resonant frequencies of 1.39 GHz; while that of 3DIMA-Exp2 was 1.2 at the resonant frequencies of 1.35 GHz. In addition, the measured radiation pattern of the 3DIMA-Exp1 has smaller back lobe and higher gain value than those of the 3DIMA-Exp2. This result indicates that the waving direction of conductive yarns may have a significant impact on electromagnetic performance of textile structural antennas.

Effect of conductive yarn crimp in radiation patch on electromagnetic performance of 3D integrated microstrip antenna

A three-dimensionally integrated microstrip antenna (3DIMA) is a microstrip antenna woven into the three-dimensional woven composite for load bearing while functioning as an antenna. In this study, the effect of conductive yarn crimp on electromagnetic performance of 3DIMAs are investigated by designing, simulating and experimental testing of two microstrip antennas with different patch woven structures: one woven in plain weave pattern with most yarn crimp and the other woven orthogonally without yarn crimp. The measured voltage standing wave ratio (VSWR) of the crimp free 3DIMA was 1.05 at the resonant frequency of 1.31GHz; while that of the crimped 3DIMA was 1.78 at the resonant frequency of 1.41GHz. In addition, the measured radiation pattern of the crimp free 3DIMA in its radiating patch has smaller back lobe and side lobes than those of the crimped 3DIMA. This result indicates that yarn crimp may have a negative impact on electromagnetic performance of textile structural antennas.

Effect of a surface resin layer covering the radiating patch on performance of a three dimensional integrated microstrip antenna

A three dimensional integrated microstrip antenna (3DIMA) is woven into a 3D orthogonal woven composite to possess load-bearing capability while functioning as an antenna. In this article, the effect of a 1 mm resin layer on the radiating patch of a 3DIMA on its performance is investigated using both simulation and experimental methods. The simulation work is performed using the antenna simulation software before fabrication. The 3DIMAs with and without a resin layer are designed, manufactured, and tested. The results show that the resonant frequency and the gain value of the 3DIMAs with a resin layer on its radiating patch are 1.36 GHz and —3.6 dB, while those of the 3DIMAs without the resin layer are 1.41 GHz and 0.5 dB. This indicates that a resin layer on the radiating patch may hinder the performance of composite antennas and therefore should be minimized.