Operating Frequency Band Research Articles

Design of a Reconfigurable Band-notched Wideband Antenna using EBG Structures

A compact WLAN band-notched reconfigurable wideband antenna using two mushroom-like electromagnetic band-gap (EBG) structures is proposed in this paper. It is designed based on a dual wideband microstrip feed patch antenna with operating frequency bands of 2.2-3.7 GHz and 4.8-6 GHz. One of the EBG cells is positioned alongside the feed line, while the other EBG cell is laid on the back of the substrate. The patch or ground of the two EBG units are fed with a stronger current through a ground slot and a parasitic stub respectively, and the connections between the EBG structures and the antenna are controlled by loading a PIN diode with two 56 pF DC blocking capacitors. The advantage of this proposed design is that the antenna and the EBG unit can be designed independently. The proposed antenna has an overall size of 35×46×1.6 mm3. When testing the S11 of the antenna, the influence of the bias circuit on the antenna is also considered. The measured results show that the proposed antenna can generate two notched bands of 2.3-2.49 GHz and 5.11-5.51 GHz of WLAN, and the realized gain in the notch bands can be reduced to -2.65 dBi and -4.55 dBi, respectively, demonstrating its anti-interference characteristics, and can be applied in band notch broadband communication systems or anti-interference communication equipments such as unmanned aerial vehicles and radars.

Wideband Center-fed Stacked Patch Circularly Polarized Antenna used in Phased Array

A center-fed circularly polarized stacked patch antenna (CF-CPSPA) with enhanced axial-ratio (AR) bandwidth is proposed in this paper. The antenna is composed of two microstrip patches, the lower patch consists of a circular pad, an elliptical-ring, and two branch lines connecting them, which is used to realize the center-fed condition, and the upper patch is an elliptical patch to achieve the wide band performance. Firstly, two center-fed linearly polarized stacked patch antennas with wide band are designed, one mode radiated with x polarization, and the other generates y polarized radiation. Next, the orthogonal modes of two linearly polarized antennas are combined together by a specific design. Finally, the approximate equal amplitude and quadrature phase difference of the introduced modes are achieved in the operating frequency band with proper parameters analysis. And the impedance bandwidth and 3dB AR bandwidth is improved to 30.4% and 16.5%.

Multiband SINC-slotted Patch Antenna for 5G Applications

In this work, we presented the design, analysis and optimization of the multiband slotted antennas based on SINC function for 5G applications. The proposed antennas are designed and modelled by CST Studio Suite software. A parametric study is performed to determine sinc function parameters that control the performance of the proposed antenna. The parametric study is implemented by varying the amplitude of the sinc function, the frequency, the location of the slot along Y-axis, the slot width and the slot window (number of cycles). The simulated results showed that the designed slotted antennas in this paper exhibits multiband operation and they offer the feasibility of controlling and adjusting the resonant frequency by changing the sinc function parameters. The proposed antennas have various resonant frequencies at around 1.5 GHz, 2.65 GHz, 5 GHz and 5.8 GHz covering the 5G sub-6 GHz band. Extensive simulation process were carried out to determine the optimum antenna performance and three antennas were selected based on the reflection characteristics and number of operation frequency bands. Finally, the three selected antennas were manufactured and their performance were measured in the lab for validation. Experimental results showed that an excellent agreement between the measured and simulated results was achieved.

Design and analysis of quasi‐lumped notch filter with extended upper pass band

AbstractThis paper presents a hybrid technique‐based compact narrow band stop filter design for broadband applications. It provides the rejection of 60 dB at the centre frequency of 2.25 GHz without any stop band harmonics over the required frequency band of operation, i.e. 1–10 GHz. This filter is highly appropriated for the rejection of undesired bands for RADAR, electronic warfare, and military communications.

Acoustic wave devices based on piezoelectric/ferroelectric thin films for high-frequency communication systems and sensing applications

Surface acoustic wave (SAW) and bulk acoustic wave (BAW) based radio-frequency (RF) filters dominate in handsets markets mainly because they have miniature size so multiple filters can be used but take up very small board area. Besides, due to their inherent advantages, such as low insertion loss, relatively high resonant frequency, and miniature size, their application in the physical and biochemical sensing fields has also gradually expanded. The successful implementation requires specific knowledge of acoustic wave properties, the working mechanisms, material properties, and device design. So, in this review, we survey the SAW and BAW filter technology by discussing the working principles and the comparison between the operation frequency band allocations. In addition, the approaches to enhance the performance including the selection of single crystal/ferroelectric materials for BAW and the structure design optimization for SAW are introduced with discussions for further improvement. Then, flexible SAW and BAW devices are also presented and their new application opportunities in the fields of skin-like electronics and wearable health monitoring devices can be foreseen. Finally, the potential challenges of high frequency, wide bandwidth, miniaturization, and compatibility with the integrated circuits (IC) manufacturing process are overviewed as well.

A novel arc‐shaped four‐port wideband (21.8–29.1 GHz) MIMO antenna with improved characteristics for 5G NR networks

SummaryA novel antenna system that utilizes multiple‐input and multiple‐output (MIMO) technology to suit the requirements of 5G applications is proposed in this article. The antenna has a wide operating bandwidth and high isolation in n257/n258/n261 5G bands. The suggested arc‐shaped MIMO antenna is composed of four similar patch units with modified ground planes arranged in a four‐port configuration and is made on a Rogers RT/duroid 5880 substrate, which measures 31.891 × 37.5885 × 0.508 mm3. The prototype of the suggested MIMO antenna is realized to confirm the obtained simulated results and validate the proposed design. The four‐port MIMO antenna features a broad frequency range of 7.3 GHz from 21.8 to 29.1 GHz, a peak gain of 5.76 dBi at 29 GHz, and a good isolation less than −18 dB. The proposed antenna's MIMO performance is evaluated by analyzing several diversity parameters. The findings of the evaluation demonstrate an envelope correlation coefficient (ECC) value of less than 0.001, a diversity gain (DG) value exceeding 9.995 dB, and an average mean effective gain (MEG) of −3 dB within the operational frequency band. The suggested MIMO antenna's compact size and impressive performance make it a suitable choice for intended n257/n258/n261 5G NR networks.

Ultra-wideband absorber based on graphene surface with polarization insensitivity under large angles

In this paper, a frequency-selective absorber with large-angular stability under oblique incidence is present. The absorptivity of the structure can be reached to maximum by impedance matching and parameter optimization method under a specific angle (40°), which ensures an excellent absorption response within 60° oblique incidence. This method solves the problem that the absorptivity of traditional absorbers deteriorates with the increase of incident angle. The absorber consists of a three-layer structure: two lossy layers and a metal ground layer, the equivalent circuit model is discussed and the operating frequency band is widened by generating electric resonances and magnetic resonances. Due to the high symmetry of the structure, the absorber has good polarization insensitivity. Numerical simulation shows that from 4.4 to 20 GHz, the absorptivity of the structure is above 90% within 40° oblique angle of incidence. Finally, the design plays an important role in military stealth and preventing electromagnetic interference.

Multipath-controlled bidirectional metasurface for multitasking polarization regulation and absorption.

In the design of metasurfaces, integrating multiple tasks into a single small unit cell and achieving regulation through various paths pose a serious challenge. In this paper, a multipath-controlled bidirectional metasurface (MCBM) is designed to achieve polarization regulation, perfect absorption and total reflection as multitasking functions. The findings demonstrate that under different excitation conditions, when co-planar polarized terahertz (THz) waves are incident normally on the metasurface, the MCBM can convert co-planar polarization to cross-polarization, co-planar polarization to circular polarization wave in reflection mode, and co-planar polarization to cross-polarization in transmission, respectively. When co-planar polarized THz waves are incident from the back side of the metasurface, the tasks of MCBM change to broadband perfect absorption, total reflection, and transmission co-planar polarization to cross-polarization conversion. Remarkably, all operating frequency bands of these tasks are very approximate. Additionally, the multitasking functions can be switched by altering the excitation conditions, and their performance can be regulated through multipath controls, such as the temperature, voltage, and polarization status. Our design provides an effective strategy for multipath-controlled multitasking integrated devices in the THz band.

Amplitude methods for forming frequency-independent radiation characteristics of multibeam reflector antennas

The trend towards expanding the operating frequency ranges of radio-electronic equipment has led to an increasing interest in recent years in the study of ways to constructing multi-beam frequency-independent reflector antennas, which requires systematization of the principles and methods of their construction. When constructing reflector antennas, methods based on the selection of the directional properties of the feeds and methods based on the selection of the frequency-selective properties of the reflectors are used. Methods based on the choice of directional properties of feeds are divided into methods using horn feeds and methods using feeds in the form of cluster arrays with intersecting apertures. Horn feeds are used to create single-beam reflector antennas. Using cluster arrays, it is possible to form a plurality of beams of frequency-independent partial radiation patterns. Using the example of a hybrid reflector antenna, the possibility of forming nine beams in the azimuthal sector of 20° with a beam width of 3.2° ± 0.45° in the frequency band from 2 to 8 GHz is shown. The level of side lobes outside the working sector in the operating frequency band does not exceed –35 dB, the slope of the direction-finding characteristics varies from 4.8 to 9.8 dB/deg. Among the methods based on the choice of selective properties of reflectors, there are methods using frequency-selective surfaces and methods using corrective coatings on the working surface of the reflector. Frequency-selective surfaces are made in the form of wire meshes with variable pitch, in the form of a set of parabolic plates and in the form of a set of square waveguides with a side size ranging from half-wave at the upper frequency in the middle part of the reflector to half-wave at the lower operating frequency at the edges of the reflector. The disadvantages of using frequency-selective surfaces are the complex and expensive design of the reflector, low antenna efficiency, high side lobes and the need to use a large absorbing screen. When implementing the method using corrective coatings, the separate functions of a frequency-selective surface and a radio-absorbing screen are combined in one structural element – a frequency-dependent corrective coating applied to the working surface of the reflector. Among the advantages of this method, it is worth noting the simple design of the reflector and the possibility of its operation at any polarization, since the reflection characteristics of the coating are practically independent of the type of polarization. A common disadvantage of reflector antennas based on the choice of frequency-selective properties of reflectors is distortion of the shape of the main lobe of partial patterns and a larger range of scatter in the pattern width in the operating frequency band, which prevents the formation of linear direction-finding characteristics and reduces direction-finding accuracy. Due to the low efficiency of multibeam mirror antennas built using amplitude methods for forming frequency-independent radiation characteristics, their use as transmitting antennas is impractical. The completed review and identified features of methods for constructing frequency-independent radiation characteristics can become a methodological basis for the design of broadband multi-beam reflector antenna systems for advanced radio-electronic equipment.

External airbag-type deepwater electrodynamic transducer.

An external airbag-type electrodynamic transducer structure was proposed to solve the problems of traditional electrodynamic transducers, such as limited operating depth, failure to work for a long time, and excessive buoyancy change. The driving vibrator of the transducer was placed in the oil-filled cavity to balance the hydrostatic pressure and increase the heat dissipation channel of the coil. The external sound insulation airbag was used to eliminate the dipole's acoustic radiation mode to improve the transducer's acoustic radiation ability. This study analyzed the acoustic radiation performance of the transducer and the influencing law of operating depth on the acoustic radiation performance based on an equivalent circuit containing the acoustic parameters of the airbag. Moreover, the heat dissipation capabilities of the new and old electrodynamic transducer structures were compared through thermal simulation analysis. Then, two experimental prototypes of new and old electrodynamic transducers were fabricated. The source-level test results show that, within the core operating frequency band, the two electrodynamic transducers exhibit equivalent acoustic radiation performance. The external airbag-type electrodynamic transducer has long-time deepwater operation ability, and the buoyancy change can be controlled within an acceptable range of autonomous underwater vehicle thanks to the small airbag.

A High-gain Low-sidelobe Dual-polarized Broadband Array Antenna

In this paper, we present a dual-polarized broadband low side lobe array designed for operation in the Ku-band. The antenna array operates within the frequency range of 14.0 GHz to 15.2 GHz, covering a bandwidth of over 8%. To realize this wide operational frequency, we have selected broadband microstrip antenna elements as the units of the array. In order to fulfill the demanding criteria of broadband performance and low sidelobe characteristics, we introduce a broadband low-sidelobe feeding network based on a directional coupler design. This feeding network ensures connectivity with the antenna units, resulting in a voltage standing wave ratio (VSWR) < 2 within the 14.0 GHz to 15.2 GHz frequency range. Furthermore, our antenna array achieves an array gain exceeding 21 dBi and keeps array sidelobes below -20 dB across the entire operating frequency band. Our research breakthrough addresses the critical design challenge of creating large-scale array antennas that combine broadband capabilities with high gain and minimal sidelobe interference.

W-Band FMCW MIMO System for 3-D Imaging Based on Sparse Array

Multiple-input multiple-output (MIMO) technology is widely used in the field of security imaging. However, existing imaging systems have shortcomings such as numerous array units, high hardware costs, and low imaging resolutions. In this paper, a sparse array-based frequency modulated continuous wave (FMCW) millimeter wave imaging system, operating in the W-band, is presented. In order to reduce the number of transceiver units of the system and lower the hardware cost, a linear sparse array with a periodic structure was designed using the MIMO technique. The system operates at 70~80 GHz, and the high operating frequency band and 10 GHz bandwidth provide good imaging resolution. The system consists of a one-dimensional linear array, a motion control system, and hardware for signal generation and image reconstruction. The channel calibration technique was used to eliminate inherent errors. The system combines mechanical and electrical scanning, and uses FMCW signals to extract distance information. The three-dimensional (3-D) fast imaging algorithm in the wave number domain was utilized to quickly process the detection data. The 3-D imaging of the target in the near-field was obtained, with an imaging resolution of 2 mm. The imaging ability of the system was verified through simulations and experiments.

Research on dynamic calibration and compensation method of strain-gauge type force sensor

Purpose This paper aims to propose an effective dynamic calibration and compensation method to solve the problem that the statically calibrated force sensor would produce large dynamic errors when measuring dynamic signals. Design/methodology/approach The dynamic characteristics of the force sensor are analyzed by modal analysis and negative step dynamic force calibration test, and the dynamic mathematical model of the force sensor is identified based on a generalized least squares method with a special whitening filter. Then, a compensation unit is constructed to compensate the dynamic characteristics of the force measurement system, and the compensation effect is verified based on the step and knock excitation signals. Findings The dynamic characteristics of the force sensor obtained by modal analysis and dynamic calibration test are consistent, and the time and frequency domain characteristics of the identified dynamic mathematical model agree well with the actual measurement results. After dynamic compensation, the dynamic characteristics of the force sensor in the frequency domain are obviously improved, and the effective operating frequency band is widened from 500 Hz to 1,560 Hz. In addition, in the time domain, the rise time of the step response signal is reduced from 0.29 ms to 0.17 ms, and the overshoot decreases from 26.6% to 9.8%. Originality/value An effective dynamic calibration and compensation method is proposed in this paper, which can be used to improve the dynamic performance of the strain-gauge-type force sensor and reduce the dynamic measurement error of the force measurement system.

A Low-Cost Printed Log-Periodic Dipole Array for DVB-T2 Digital TV Applications

A printed log-periodic dipole array (LPDA) for DVB-T2 Digital TV applications, covering the whole DVB-T2 UHF band from Channel 21 to Channel 69 (470 MHz–860 MHz), is presented. The presented antenna offers a compact size and a lower cost compared to both wire and similar printed LPDAs, with a normalized area of only 0.26 λ2 (where λ is the free-space wavelength at the central frequency) and a similar (or higher) average gain. It is composed of meandered radiating dipoles, and it is implemented on FR4, the cheapest dielectric substrate available on the market. Moreover, the antenna size has been reduced to an A4 sheet dimension (210 mm × 297 mm) to cut down the production cost. The antenna has been designed starting from Carrel’s theory and using a general-purpose 3D CAD, CST Studio Suite. The results show that the proposed antenna can be used for broadband applications (≈74% bandwidth) in the whole operating frequency band of Digital TV, with a satisfactory end-fire radiation pattern, a stable gain, and a radiation efficiency over the required frequency range (average values 6.56 dB and 97%, respectively).

Realization of FOI and FOD of Complex Orders

This work introduces a new realization method of fractional-order integrators (FOI) and differentiators (FOD) of complex orders. The corresponding Laplace variables of the form S±α±jβ; 0 < α, β ≤ 1, are approximated and realized via minimum-phase rational transfer functions within a frequency band. The realization is adaptive since it depends on the frequency band of operation. Proper selection of the complex order and its sign play an important role in widening up and improving the phase diagram of the approximation at high frequency. Thus, making them ideal candidates to improve the leading phase of the FOI/FOD at high frequency. The main points of this work are verified via numerical simulations.

A DODECAGON SLOTTED CIRCULAR TWO-ELEMENT SUB-6 GHZ FLEXIBLE ANTENNA FOR WEARABLE APPLICATIONS USING MODAL ANALYSIS

The sub-6 GHz 5G band has opened doors for a seamless and high-data-rate communication system connecting multiple devices. Multiple-input/multiple-output (MIMO) antennas are the backbone of such reliable communication systems with enhanced channel capacity. In this paper, a flexible two-element antenna is proposed for wearable applications. The dodecagon-slotted modified circular patch antenna with a defective ground structure gives isolation of 18 dB over the bandwidth. The antenna exhibits a gain of 3.38 dBi at the operating frequency of 4.8 GHz. A characteristic mode analysis was performed to investigate the resonance behavior of the antenna. Furthermore, specific absorption rate analysis was performed and found to be 0.790/0.314 W/kg for 1/10 g of tissue at 4.8 GHz. The MIMO diversity metrics exhibited an envelope correlation coefficient &amp;#60; 0.001, total active reflection coefficient &amp;#60; -10 dB, diversity gain &amp;asymp; 10, mean effective gain &amp;#60; -3 dB, channel capacity loss &amp;#60; 0.40 bps/Hz, and multiplexing efficiency &amp;#60; 0 over the operating frequency band.

Notice of Violation: A 3D Printed Multi-Mode Conical Dielectric Resonant Antenna With Stable Omnidirectional Radiation Patterns for 5G Vehicle Picocell Applications

Notice of Violation <br><br>“A 3D Printed Multi-Mode Conical Dielectric Resonant Antenna With Stable Omnidirectional Radiation Patterns for 5G Vehicle Picocell Applications” <br>by Xuyi Zhu, Bing Zhang, Zhijiao Chen, Yanping Zhou, Kama Huang, Tiancang Zhang, Juan Yang, and Xiao An <br>published in the IEEE Transactions on Vehicular Technology, Digital Object Identifier: 10.1109/TVT.2022.3196909. <br><br>The authors of this paper violated the IEEE’s Publication Principles. An author name was included in the Early Access version of this paper who did not contribute to the work and was added without their consent. The non-contributing author’s name has been removed <br><br> <br/> A multi-mode 3D-printed conical dielectric resonant antenna (DRA) with a stable omnidirectional pattern is proposed. It covers the band of 1.75-3.64 GHz and 4.96-6.01 GHz. Multiple modes in the conical DRA are effectively excited which are the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01δ</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03δ</sub> modes intrinsic to the dielectric resonator (DR). The combination of probe and sleeve is used to feed the DR to excite additional modes such as the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> modes and the sleeve mode respectively to further extend the bandwidth of the antenna. The sleeve also helps to tune the current distribution of the probe's high-order modes when the DRA is mounted on a finite-size ground plane. The profile of the conical DRA is properly designed to overcome the tilt of the radiation pattern by the ground plane, by which stable omnidirectional radiation patterns are achieved across the whole operating frequency band. The characteristic mode theory and an eigenmode solver are used to verify the numerical analysis. The 3D printing technology is used to fabricate the DRA. Powered LEDs are placed inside the 3D printed DRA to enable its lighting function. The proposed antenna can be fixed on the vehicle's roof for vehicle-to-everything (V2X) communication. It has satisfactory electromagnetic compatibility (EMC) with other vehicle-mounted electronic devices. It is a good candidate for 5G vehicle picocell applications.

Design of a 2–18 GHz low noise amplifier MMIC with current reused topology

AbstractA 2–18 GHz ultra wideband low noise amplifier (LNA) is illustrated in this letter. The proposed LNA adopts a two‐stage structure, which is composed of a common source amplifying stage and a cascode amplifying stage. By combining band extension matching technique, current reused topology and active bias circuit, the LNA performs excellent in gain, noise figure, power consumption, and immunization against the fluctuation of voltage supply. The LNA is implemented with a 0.18‐μm GaAs pseudomorphic high electron mobility transistor process and has a compact chip area of 1.75 × 1 mm2. The dedicated LNA achieves a measured average gain of 20.7 dB with ±1.5 dB variation all over the ultra‐wide bandwidth of 2–18 GHz. It also has a measured noise figure of lower than 1.7 dB and a measured output 1 dB compression point of higher than 5 dBm in the operating frequency band. The LNA has a low direct current power dissipation of 100 mW under a 5 V voltage supply.

Designing Fabric-based Broadband Metamaterial Absorbers for Radar Operating Frequency Bands

Designing Fabric-based Broadband Metamaterial Absorbers for Radar Operating Frequency Bands

Miniaturized circularly polarized metasurface antenna based on characteristic mode analysis

AbstractA miniaturized circularly polarized (CP) metasurface (MTS) antenna is investigated based on characteristic mode theory (CMT). The 4 × 4 square patch structure was used as the initial structure for characteristic mode analysis (CMA) and improvement using CMT to guide the evolution of antenna structures. The square ring is bent and the capacitive strips are introduced to obtain the final miniaturized MTS. Comparing the proposed MTS with traditional MTS, the proposed antenna size is significantly reduced. To give the proposed antenna a CP, a feeding structure with a 90° phase difference is designed to excite a pair of orthogonal target patterns. The final antenna structure has a reduced overall size and has circular polarization characteristics. For verification, the proposed CP MTS antenna is fabricated and measured. The measured results show an impedance bandwidth of 2.9–3.65 GHz and 3 dB axial ratio bandwidth of 3.1–3.57 GHz, and a stable gain in the operating frequency band.