Dual-band Frequency Research Articles

A Dual-Band and Low-Cost Microstrip Patch Antenna for 5G Mobile Communications

This paper investigates the numerical and experimental analysis of a low-cost and dual-band microstrip patch antenna for the fifth generation (5G) mobile communications. The numerical analysis of the proposed antenna is performed using the computational electromagnetic simulator (CEMS) software which is based on the finite-difference time-domain (FDTD) and CST software which is based on the finite integration technique (FIT). The performance of the proposed antenna designed and fabricated on a low-cost FR-4 substrate is verified with the simulated and measured results. The antenna operates at dual frequency bands which are 24 and 28 GHz. The antenna maximum gain values are 3.20 dBi and 3.99 dBi in the x-y plane at 24 and 28 GHz, respectively. The proposed antenna provides almost omni-directional patterns suitable for 5G mobile communication devices.

Metamaterial-inspired optically transparent active dual-band frequency selective surface with independent wideband tunability.

This paper presents an optically transparent active bandstop frequency selective surface (FSS) with wideband tunability of two resonance frequencies using the concept of miniaturized element FSS (MEFSS). The proposed design consists of metallic square loop arrays on a new optically transparent substrate as the top layer, a glass interlayer, and periodic patterns of cross dipoles on the substrate as the bottom layer. Two kinds of resonant elements loaded with varactors and the designed bias networks achieve two independent tunable stopbands. The proposed FSS has two large tuning ranges, one is from 1.20 GHz to 2.63 GHz and another is from 2.0 GHz to 5.9 GHz (75% and 99% with respect to the center frequency, respectively). The wideband dual-tuning mechanism is theoretically analyzed and demonstrated by deriving its equivalent circuit (EC) model. The experiment results exhibit reasonable agreement with the numerical simulation responses. This proposed design, with low profile, angular stability, polarization insensitivity, optical transparency, and wideband dual-tunability can play an important role in manipulating electromagnetic wave propagation for manifold applications.

Swastika shaped slot embedded two port dual frequency band MIMO antenna for wireless applications

Swastika shaped slot embedded two port dual frequency band MIMO antenna for wireless applications

A Study on Different Slot Position for Designing Dual Band Microstrip Antenna for 5G Wireless Communication

In this paper, four antenna designs with different slot positions for dual band frequencies are analysed. A reference antenna operating at 8 GHz is used at a dimension of 30 mm2 using Rogers RT58880 as the substrate with a dielectric constant of 2.2. Two slots are etched in order to produce a dual band. The antenna resonates at 8 GHz and 15 GHz. Return loss at 8 GHz and 15 GHz are −17.03 dB and −21.37 dB with gain at 7.39 dB at 8 GHz. By using CST Microwave Software, the simulated results are obtained. The slotted antenna produces a dual band antenna that is a suitable candidate for 5G wireless communication tool.

A 433/2400 MHz dual-band frequency synthesizer with glitch-free phase-interpolated frequency divider and hybrid post-synthesizer

A three-stage low phase noise cascaded phase locked loop (PLL) with reference quadrupler and phase-interpolated (PI) frequency divider is presented in this paper. The first stage consists of a frequency doubler and an injection locked (IL) loop. By increasing the reference frequency from 50 MHz to 200 MHz, the maximum loop division ratio is deduced, yielding to 12 dB in-band noise transfer gain suppression and larger loop bandwidth. The second stage is a fractional-N PLL. In order to mitigating the effect of quantization noise in fractional-N model, a double-orthogonal PI frequency divider is utilized. The division ratio step is reduced from 1 to 1/32, leading to 30 dB quantization noise suppression. The third stage is a hybrid charge-pump (CP) and sub-sampling PLL (SSPLL). By utilizing this hybrid structure, the third-stage output phase noise is dominated by the output clock of the second stage. The PLL is designed and simulated in 65 nm CMOS process. At 2.4 GHz, the spot phase noise are −100 and −114 dBc/Hz at 10 kHz and 1 MHz offsets respectively and the power consumption is 12 mW.

Miniaturized dual stop band frequency selective surface with broadband linear co to cross polarization conversion ability

This work presents a miniaturized angularly stable frequency selective surface (FSS) on a single layer substrate. Unit cell comprises of convoluted circular rings connected cross dipole and linear arrow headed dipole printed on both sides of the substrate. A closely spaced dual stop band resonances are obtained at 10 and 14.3 GHz with frequency ratio of 1.43. FSS shows a − 10 dB stopband bandwidth (BW) from 7.32 to 11.05 GHz (40.61%) and 12.68 to 15.97 GHz (22.97%) with >30 dB stop band rejection at center frequencies. FSS poses the features of stable performance under change in polarization and angularly stable response up to 60° incident angle. Later the proposed FSS is printed on grounded thick dielectric substrate and it shows broadband reflection type co to cross polarization conversion from 7.2 to 17.32 GHz (82.54%) with polarization conversion ratio >80% and oblique angle stability up to 35°. To the best of authors' knowledge, this is the first time in literature a single unit cell geometry with two different properties, spatial filtering on transmission and polarization conversion on reflection have been designed and analyzed in details. A finite array with size 25 × 25 of the proposed FSS is fabricated and the measured filter response shows a good agreement with simulated performance at normal and oblique incidences. The proposed FSS is used as a reflector of a dual band monopole antenna and the simulation results shows gain improvement of 5.51 and 3.8 dB at the two stopband frequencies.

Substrate integrated waveguide fed dual band quad-elements rectangular dielectric resonator MIMO antenna for millimeter wave 5G wireless communication systems

A rectangular dielectric resonator based connected ground quad-elements MIMO antenna fed using substrate integrated waveguide (SIW) is proposed for millimeter-wave 5G application. SIW in TM10 mode was used to excite multiple modes in the dielectric resonator to achieve multiple resonance. An individual element of the proposed MIMO antenna is arranged in a cross shaped structure to achieve polarization and spatial diversity. The proposed MIMO system operates at dual operating frequency bands having impedance bandwidth of 24% (24.50–27.50 GHz) and 12% (33–37 GHz). The isolation better than 22 dB and 17 dB is achieved throughout the proposed bands without using any additional isolation techniques. The proposed MIMO antenna has a peak gain of 9.9 dB and minimum radiation efficiency of 96%. It radiates in a broadside direction with acceptable MIMO diversity results where envelope correlation coefficient is below 0.15, channel capacity loss is below 0.6 bits/sec/Hz, diversity gain of 9.98 dB, and total active reflection coefficient below −10 dB over the desired band of operation. The prototype of the quad-elements SIW fed DRA MIMO was manufactured after which the antenna and diversity performance parameters were measured and satisfactory correlation is observed.

Dual-Band Antenna With Wideband Harmonic Suppression Based on Dual-Function Slot Structure

A dual-band antenna with wideband harmonic suppression based on dual-function slot structure is presented for the future microwave and millimeter-wave communication system in this letter. In the low-frequency band, the slot serves as the radiator, and both two parasitic patches and four slot-stubs are also introduced in the slot to increase the bandwidth. In the high-frequency band, this slot works as the feeding structure, which excites the 2 × 4 millimeter-wave patch array. Meanwhile, the wideband harmonic suppression between dual frequency bands is achieved by loading both four open-stubs on this slot and a T-stub in this slot. A prototype is fabricated and measured to validate the design, which covers a dual band of 5 and 27 GHz. Their measured -10 dB relatively impedance bandwidth is 21.9% and 13.7%, respectively. Moreover, the measured reflection coefficient is higher than -1 dB and the measured gain is lower than -10 dBi from 7 to 21.5 GHz, showing the characteristic of good harmonic suppression.

Quad-channel independent wavefront encoding with dual-band multitasking metasurface.

Achieving multiple electromagnetic (EM) functionalities on a shared aperture in dual frequency bands is crucial for many applications; however, existing dual-band metasurfaces are affected by limited channels or narrow bandwidths. Herein, we propose a reflective coding metasurface that empowers four independent EM functionalities in quad-polarization channels in two wide frequency bands. By integrating quasi-I-shaped and cross-shaped metastructures, the meta-atom can feature independent phase modulation for two orthogonally linear and two decoupled circular polarizations at low and high frequencies, respectively. To validate the proposed metasurface, a multifunctional metadevice is designed that integrates beam deflection, diffuse scattering, and vortex beam generation. Both experimental and simulation results indicate distinct wavefront tailoring in each channel. The proposed multi-functional metasurface with low cross-talk and independent phase modulation depending on frequencies and polarizations may unlock the metasurfaces' potentials for complete wavefront control in EM function integration, multiple channel communication, polarization optics, etc.

3-D Printed All-Dielectric Dual-Band Broadband Reflectarray With a Large Frequency Ratio

This communication proposes a new all-dielectric broadband dual-band reflectarray with a large frequency ratio using low-cost 3-D printing. In contrast to conventional reflectarrays using metallic resonant cells or dielectric slabs as phasing elements with full metal ground, the proposed design uses air as the phasing element and a stepped dielectric mirror structure as the ground. In this way, the metal ground is removed, which makes the design an all-dielectric one. Taking advantage of the dielectric mirror that only exhibits a bandgap in the predesigned band while allowing electromagnetic (EM) waves to pass through it at the frequency out of the bandgap region, a dual-band reflectarray is obtained. By properly selecting the bandgap frequency of the dielectric mirror, the dual-band frequency ratio is scalable and can be very large. Furthermore, instead of using a metallic or dielectric resonator based on resonance, air layers with linear phase response are adopted as the phasing element. Thus, the reflectarray shows broadband and stable performance over the dual-band. Compared with the state-of-the-art works using printed circuit boards (PCBs) or microfabrication, the proposed design is low cost and lightweight, and can be rapidly prototyped. For proof-of-concept, a prototype operating at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> -band and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> -band with a frequency ratio of 2.7 is printed and measured.

Design of dual‐band filtering power dividers with designable port‐to‐port isolation network

In this article, a class of dual-band filtering power dividers is proposed with simultaneous realization of good designable port-to-port isolation. A filtering branch, including two cascaded stub-loaded half- wavelength resonators and coupled-line sections, are introduced together with the proposed isolation network to simultaneously achieve controllable bandwidth, frequency ratio in dual-band power division, as well as the port-to-port isolation. To construct dual-wideband power division, two coupled multimode resonators could be used to form the filtering branches, while the proposed isolation network with additional open stub at each output port is utilized to obtain a wide port-to-port isolation band. Theoretically, a design method for analyzing the dual-band frequency response of the power division is presented, while a dual- or wide-band isolation is achieved by introducing multiple transmission zeros in the S32-magnitude. Finally, two prototype power dividers on the microstrip-line structure are designed and fabricated. The simulated and measured results agree well with each other, which verify the theoretical predications.

Design of a Compact Dual-Band MIMO Antenna System with High-Diversity Gain Performance in Both Frequency Bands.

A compact four-element dual-band multiple-input and multiple-output (MIMO) antenna system is proposed to achieve high isolation and low channel capacity loss. The MIMO antenna was designed and optimized to cover the dual-frequency bands; the first frequency band is a wide band, and it covers the frequency range of 1550–2650 MHz, while the other frequency band covers the 3350–3650 MHz range. The measured wide-band impedance bandwidths of 1.1 GHz and 300 MHz were achieved in the lower and upper frequency bands, respectively. The proposed structure consists of four novel antenna elements, along with a plus-sign-shaped ground structure on an FR4 substrate. The overall electrical size of the whole dual-band MIMO antenna system is (W) × (L) × (H) for the lower frequency band. It achieved greater than 10 and 19 dB isolation in the lower and upper frequency bands, respectively. The antenna system accomplished an envelope correlation coefficient of in the lower frequency band, while it achieved in the higher frequency band. The computed channel capacity loss remained less than almost 0.4 bits/s/Hz in both frequency bands. Therefore, it achieved good performance in both frequency bands, with the additional advantage of a compact size. The proposed MIMO antenna is suitable for compact handheld devices and smartphones used for GSM (Global System for Mobiles), UMTS (Universal Mobile Telecommunications Service), WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), 5G sub-6 GHz, PCS (Personal Communications Service), and WLAN (wireless local area network) applications.

Influence of Freeze-Thaw Cycles on Acoustic Emission Characteristics of Granite Samples under Triaxial Compression

Understanding the acoustic emission (AE) characteristics of rocks that have undergone freeze-thaw cycling is of great significance for the use of AE technology to monitor the stability of rock masses in cold regions. A series of freeze-thaw cycling experiments and triaxial compression AE tests of granite samples were performed. The results show that, with an increasing number of freeze-thaw cycles, the P-wave velocity and peak AE intensity of granite show a substantial downward trend. The AE ringing counts during triaxial compression can be divided into three stages: abrupt period, calm period, and failure period. The overall change of the characteristic AE signal of granite samples that underwent different freeze-thaw cycles is the same. The AE signal during the destruction of granite occurs in clear dual dominant frequency bands. The peak frequency increases with increasing load time, and this trend becomes less clear as the number of freeze-thaw cycles increases. Overall, the peak frequency distribution tends to change from high to low with an increasing number of freeze-thaw cycles. The results provide basic data for rock mass stability monitoring and prediction, which is of great significance for engineering construction and management in cold regions.

Gain augmentation of a dual‐band dielectric resonator antenna with frequency selective surface superstrate

Gain augmentation of a dual-band antenna with different bandwidths using superstrate is presented in this paper. Initially, the dual-band radiator is designed using a rectangular dielectric resonator (DR). The fundamental mode TE111 of the rectangular DR resonates at 3 GHz over a narrowband (BW = 5.08%). The upper wideband (BW = 20% with center frequency 5.86 GHz) is obtained by the amalgamation of two hybrid modes with higher-order TE113 mode. The dielectric waveguide model is used for the theoretical analysis of two radiating modes of the rectangular DR. Further, a dual-band frequency selective surface with bandpass response is designed and loaded as a superstrate above the DR antenna for gain improvement in both the bands, which leads to a gain augmentation of 1.8 dBi and upto 3.5 dBi in the lower and upper band respectively. At last, the proposed design is implemented practically, and measurement results are portrayed to compare with simulation results that agree reasonably well.

Synthesis Design of Dual-Band Differential Phase Shifters With Independent Filtering Passbands and Predetermined Phase Shifts

This article proposes the synthesis design method of the dual-band differential phase shifters with independent filtering passbands and predetermined phase shifts. The filtering unit of the proposed phase shifter adopts a simple branch-line structure, which possesses its characteristics of controllable dual-band frequency ratios and bandwidths. Meanwhile, the Schiffman phase alignment element holds the capability of achieving different predetermined phase shifts in dual band. In our design, dual-mode resonator and dual-mode J-inverter models for the filtering units are equivalently established, and the amplitude and phase closed-form formulas for the proposed dual-band phase shifter are further numerically obtained for the first time. This proposed work features new synthesis method, integrated higher order filtering response with two independently prescribed bandwidths, and concurrent predetermined dual-band phase shifts. Design procedures are provided in detail for a quick design. Finally, two dual-band phase shifters with different frequency ratios and phase shifts are designed and demonstrated. The experimental and measured results match well.

Investigation of dualband fan-shaped microstrip bandpass filter

In this study, design and simulation of microtrip bandpass filter is presented using RT/Duroid 6010.2 lm substrate. This filter has fan-shaped topology with small dimensions of 12x12 mm2, designed for dual band frequencies at 3.41 and 6.14 GHz. The insertion loss and return loss of initial band at 3.41 GHz are -0.7 and -38.224 dB respectively and its bandwidth ranged from 3.3561 to 3.48 GHz. On the other hand, for 2nd band at 6.14 GHz, the insertion loss and return loss have been -1.377 and -14 dB respectively with bandwidth ranged from 6.0951 to 6.1782 GHz.

Concurrent Dual-Band Inverter-Based Low Noise Amplifier (LNA) for WLAN Applications

low noise amplifier (LNA); concurrent; dual-band; inverter-basedIn this paper, a two-stage concurrent dual-band low noise amplifier (DB-LNA) operating at 2.4/5.2-GHz is presented for Wireless Local Area Network (WLAN) applications. The current-reused structure using resistive shunt-shunt feedback is employed to reduce power dissipation and achieve a wide frequency band from DC to-5.5-GHz in the inverter-based LNA. The second inverter-based stage is employed to increase the gain and obtain a flat gain over the frequency band. An LC network is also inserted at the proposed circuit output to shape the dual-band frequency response. The proposed concurrent DB-LNA is designed by RF-TSMC 0.18-µm CMOS technology, which consumes 10.8 mW from a power supply of 1.5 V. The simulation results show that the proposed DB-LNA achieves a direct power gain (S 21 ) of 13.7/14.1 dB, a noise figure (NF) of 4.2/4.6 dB, and an input return loss (S 11 ) of −12.9/−14.6 dBm at the 2.4/5.2-GHz bands.

Heterodyne Receiver for Origins

The Heterodyne Receiver for Origins (HERO) is the first detailed study of a heterodyne focal plane array receiver for space applications. HERO gives the Origins Space Telescope the capability to observe at very high spectral resolution (R = 107) over an unprecedentedly large far-infrared (FIR) wavelengths range (111 to 617 μm) with high sensitivity, with simultaneous dual polarization and dual-frequency band operation. The design is based on prior successful heterodyne receivers, such as Heterodyne Instrument for the Far-Infrared /Herschel, but surpasses it by one to two orders of magnitude by exploiting the latest technological developments. Innovative components are used to keep the required satellite resources low and thus allowing for the first time a convincing design of a large format heterodyne array receiver for space. HERO on Origins is a unique tool to explore the FIR universe and extends the enormous potential of submillimeter astronomical spectroscopy into new areas of astronomical research.

Time Correction of Ocean-Bottom Seismometers Using Improved Ambient Noise Cross Correlation of Multicomponents and Dual-Frequency Bands

Abstract An effective approach was developed for identifying and correcting ocean-bottom seismometer (OBS) time errors through improving ambient noise cross-correlation function (NCCF) analysis and combination with other methods. Significant improvements were illustrated through analyzing data from a passive-source seismic experiment in the southwestern sub-basin of the South China Sea. A novel method was first developed that can effectively identify errors in the sampling frequency of the OBS instruments. The traditional NCCF method was then expanded by increasing the analyzed data spectrum from a single-frequency band to dual-frequency band pairs, thus doubling the number of available data points and substantially improving the time correction quality. For data with relatively low signal-to-noise ratios, the average time errors were reduced from the original average values of 60–80 ms by the conventional methods to &amp;lt;40 ms using the improved approaches. The new multistep procedure developed in this study has general applicability to analysis of other OBS experiments. The demonstrated significant improvements in the data quality are critical for advancing seismic tomography and other modern marine geophysical studies that require high accuracy in the OBS data.

Development of Microstrip Antenna for Satellite Application at Ku/Ka Band

Antennas are the most important unit in almost all wireless communications, which played the key of transmitting the radiating electromagnetic waves after converting it from electrical signal. In this paper, designed an antenna that is capable to operate at frequencies between 12 GHz – 18 GHz for Ku band, and 26.5 GHz – 40 GHz for Ka band. This antenna was designed to overcome the narrow bandwidth, low gain, and large size of most satellite application antennas. By using a square shaped patch on a 4.3 dielectric constant substrate, modified and optimized the dimensions of the patch element, this antenna operated on dual-band frequencies between 12 GHz – 18 GHz and 26.5 GHz – 40 GHz, which satisfies the required bandwidth for satellite application. The antenna design was simulated using CST Microwave Studio software to analyze and evaluate the performance of the antenna design visibility.