Dual-band Frequency Research Articles

Dual-Band Free-Positioning Transmitting Coil for Multiple-Receiver Wireless Power Transfer

In recent years, the requirement for a compact wireless power transfer (WPT) system that can supply power to multiple devices in various practical usage scenarios has been attracted many researchers. The receiver (Rx) misalignment problem is contributory to the power transfer efficiency (PTE) degradation. Moreover, in a multiple-output WPT system, the overall system efficiency is also affected by cross-coupling between receivers. This paper proposes a dual-band free-positioning transmitting coil (FPDB-Tx) for multiple-receiver WPT. A three-dimensional Tx structure is modeled by investigating the current direction on each coil loop to adapt the Rx angular and axial misalignment. The Tx configuration is designed following a wireless charging box concept, where multiple Rx devices can receive energy freely without a null efficiency point. The mutual inductance is examined by a mathematical method in various Rx orientations to verify the free-positioning characteristic. Furthermore, an equivalent circuit model of the WPT system is theoretically analyzed to obtain dual operating frequency bands and then maximized the PTE. The experimental results show that the proposed WPT system achieves a stable PTE in various Rx positions. Especially, the WPT system has a maximum PTE of 97.27% and 91% at 6.78 MHz and 13.56MHz, respectively.

A compact fractal dual high frequency band notched UWB antenna with a novel SC-DGS

A compact and novel fractal dual band notched UWB antenna with time domain characteristics is presented. A tapered microstrip fed circular fractal radiating patch along with a novel semi circular defected ground structure produce − 10 dB bandwidth from 3.73 to 16.7 GHz. The proposed antenna is a miniature size of 16 × 21 mm2 and is printed on FR-4 substrate with two high frequency notched bands from 7.29–7.76 GHz to 9.53–11.17 GHz to notch X-band satellite communications link by incorporating L and C-shaped parasitic elements respectively. The proposed antenna exhibits a uniform gain of 2–4.26 dBi, flat group delay around 1.2 ns, and peak radiation efficiency about 96% in operating frequencies makes it suitable for wireless UWB portable devices.

Design and development of dual band antenna for sub-6 frequency band application

The present review paper is discussed the overview and literature survey on dual band antenna for sub-6 frequency band application using FR-4 material. However, the primary aim is to design the dual band antenna for below 6 GHz frequency application. Antenna technology is shifted from exterior antenna to an interior one. Due to high speed transmission of signal, transmit single frequency band to dual frequency band and single frequency band to multi frequency band antenna and now antenna requirements changed from single-band to dual-band, now antenna diversity changed from SISO to MIMO implementations. In this paper, main focus is on designing of dual band antenna for 6 GHz application.

A Low-Profile Dual-Band Filtering Hybrid Antenna With Broadside Radiation Based on Patch and SIW Resonators

This paper presents a differentially fed dual-band hybrid antenna with broadside radiation, enhanced bandwidth, and high selectivity. The proposed antenna is constructed using a single-layer substrate based on rectangular patch resonator and substrate integrated waveguide (SIW) cavity. Herein, TM10 and TM12 modes of the rectangular patch resonator, together with TE21 and TE23 modes of the rectangular SIW cavity, are selected for resonances in the concerned dual-band radiation. Among them, TM10 and TE21 are employed for the lower passband, while TM12 and TE23 for the higher passband. Besides, for achieving broadside radiation performances in both bands, two arrays of shorting pins are loaded in the rectangular patch resonator and the constituted electric wall surround the rectangular SIW cavity is properly truncated to reshape the radiation patterns of TM12 and TE23, respectively. Notably, the resonant and radiation properties of all the involved modes are obtained with theoretical deduction. Furthermore, the cascaded trisection composed of the SIW cavity, the patch resonator, and the radiation impedance creates two radiation nulls in each upper stopband of both passbands and the mixed coupling between two resonators generates another radiation null to be located in the lower stopband of the higher passband. For demonstration, a prototype antenna with the dual bands at 3.5 and 5.8 GHz is fabricated and tested. The measured results show that the antenna has achieved an improved bandwidth (|Sdd11| < -10 dB) from 3.26 to 3.58 GHz and 5.60 to 5.90 GHz, respectively, with stable broadside gains of around 8.5 dBi. In addition, in the stopband, three radiation nulls are created at 3.71, 5.32, and 6.12 GHz for effective enhancement of dual-band frequency selectivity.

38/60-GHz Dual-Frequency 3-Stage Transformer-Based Differential Inductor-Peaked Rectifier in 40-nm CMOS Technology

This letter presents a 38/60-GHz dual-frequency band 3-stage transformer-based inductor-peaked differential rectifier in a 40-nm CMOS technology. The rectifier is used in a wirelessly powered receiver in a monolithic IoT transponder. Its sensitivity is a bottleneck for the transponder’s range. With the dual-frequency operating function, the wirelessly powered distance could be optimized based on the selected frequency band. In this letter, a new vertical integration transformer with a compact size is proposed and implemented to achieve stage-cascading, inductor peaking, and dual-frequency matching functions simultaneously. In addition, bulk-drain-connected transistors further improve the rectifier’s efficiency and sensitivity. In this combination, the 3-stage transformer-based inductor-peaked rectifier improves sensitivity at 38 and 60 GHz frequency bands. The 1-V sensitivity is −6 dBm at the 38–40-GHz frequency band and −5 dBm at 57–64-GHz frequency band. This mm-wave dual-band rectifier achieves the peak 1-V sensitivity of −7.8 dBm at 40 GHz.

Miniaturized Angularly Stable Dual Band Frequency Selective Surface for K and Ka Band

A single layer novel compact frequency selective surface which is used in reflector antenna is designed and simulated. The proposed unit cell reflects electromagnetic waves in K and Ka band with maximum reflection occurring at 22.62 GHz and 35.44 GHz respectively. The designed FSS find its application in satellite communication. A crossed dipole structure in center and two-legged structure in corners with square loop in each quadrant makes the FSS unit cell structure. The FSS is designed with oblique incidence for transverse electric and transverse magnetic polarization with return loss 0.3 dB in 22.62 GHz and less than 0.5 dB in 35.44 GHz. The proposed work shows frequency independence against oblique angle of incidence. The simulated result from CST microwave studio is compared with other similar works.

Design and miniaturization of dual-band Wilkinson power dividers

Abstract In this paper, four differently shaped Wilkinson power dividers are presented by selecting the same physical length of two-section transmission lines, dual arbitrary frequency band Wilkinson power dividers can be achieved. The 2.4 GHz (WLAN) and 5.9 GHz (DSRC IEEE 802.11p) frequency bands are selected to complement the future development of multi-band, multi-standard transceivers. To improve physical separation and electrical isolation between the two output ports a parallel RLC circuit is employed. For verification, the simulated and measured performance results of dual-band Wilkinson power dividers implemented on the Rogers 4003C laminate are presented. The measurement results for the fabricated Wilkinson power dividers were in good agreement with theoretical simulation results and show dual-band characteristics.

A miniaturized flexible frequency selective surface for dual band response

AbstractIn this paper, a novel miniaturized and flexible dual band frequency selective surface (FSS) is presented. This FSS provides effective shielding in X-band and Ku- band, with a frequency response of 9.4 and 16.7 GHz, respectively. The proposed FSS provides 924 MHz bandwidth at X-band and 1.34 GHz bandwidth at Ku-band with an insertion loss of 20 dB. Moreover, the proposed design is polarization-independent and it provides stable frequency response at various angles of incidences for both transverse electric and transverse magnetic modes. More significantly, the proposed FSS analyzed the bandstop response of the selective frequency and also is suitable for conformal applications. A prototype of the proposed FSS is fabricated. The measured results and simulated results are good in agreement.

Miniaturized Dual-Band FSS Suitable for Curved Surface Application

Based on a single metallic layer printed circuit board (PCB), a miniaturized dual-band frequency selective surface (FSS) is proposed that could fulfill thin substrate design for curved application and provide stable resonant frequency. Due to the property that the element size can be altered by using different thicknesses of substrate, the FSS could either be designed for the compact size or in a very thin substrate. Two practical designs for dual-band wireless local area network (WLAN) are demonstrated featuring a flexible and straightforward design method. The compact one has an element size of only 5.2% of the free space wavelength at the lower resonant frequency, which is the smallest dual-band WLAN FSS by using only one metallic layer in published literature. Another thin substrate design (0.4 mm PCB) is fabricated and measured to confirm that the FSS exhibits stable resonant frequency on curved surfaces with different curvatures. The measured frequency shift is only 2.2%, which is among the smallest percentage in the literature.

Ultra-thin and high-efficiency full-space Pancharatnam-Berry metasurface.

Full-space metasurfaces (MSs) attract significant attention in the field of electromagnetic (EM) wave manipulation due to their advantages of functionality integration, spatial integration and wide applications in modern communication systems. However, almost all reported full-space metasurfaces are realized by multilayer dielectric cascaded structures, which not only has the disadvantages of high cost and complex fabrication but also is inconvenient to device integration. Thus, it is of great interest to achieve high-efficiency full-space metasurfaces through simple design and easy fabrication procedures. Here, we propose a full-space MS that can efficiently manipulate the circularly polarized (CP) waves in dual frequency bands by only using a single substrate layer, the reflection and transmission properties can be independently controlled by rotating the optimized meta-structures on the metasurface. Our full-space metasurface has the potential to design multifunctional devices. To prove the concept, we fabricate the device and measured it in microwave chamber. For the reflection mode, our metasurface can behave as a CP beam splitter at the frequency of f1 = 8.3 GHz and exhibit high efficiencies in the range of 84.1%-84.9%. For the transmission mode, our metasurface acts as a meta-lens at the frequency of f2 = 12.8 GHz for the LCP incidence, and the measured relative efficiency of the meta-lens reaches about 82.7%. Our findings provide an alternative way to design full-space metasurfaces and yield many applications in EM integration systems.

The Design and Simulation of Dual-band Beidou Navigation Receiver LNA

The Beidou satellite navigation receiver requires receiving multi-band signals to ensure more accurate and reliable positioning and navigation. According to the working frequency bands B3I and L1 of the system, we propose a low-noise amplifier which is based on Infineon’s BFP740FESD transistor. We employ the ADS software to simulate and optimize the low-noise amplifier input, and adopt the conjugate matching two-stage amplifier circuit. The simulation results show that the gain Gain ≧ 30dB in the L1 and B3 dual frequency band, the input and output standing wave ratio VSWR < 1.5, the noise coefficient < 1.0dB, and the out-of-band suppression is more than -40dB, which effectively reduces the out-of-band noise interference.

Dual‐band bandpass filter using two simple coupled microstrip rings

AbstractA new dual‐band bandpass filter (BPF) using two very simple coupled microstrip rings is proposed in this paper. The two identical 3λg/2 microstrip rings are coupled each other with λg/2 coupled length, resulting in the generation of dual frequency bands with multiple transmission zeros (TZs). Theoretical deduction is presented to verify the proposed structure. The center frequencies and bandwidths of the two passbands can be tuned by controlling the impedance parameters of the microstrip rings. For demonstration, a prototype example of this dual‐band BPF is fabricated and characterized. The measured results show that it has high selectivity and great return losses of passbands with multiple TZs at the stopband.

PERBANDINGAN ANTENA MIKROSTRIP ARRAY DUAL BAND DENGAN PENCATUAN MICROSTRIP LINE DAN ELECTROMAGNETICALLY COUPLED (EMC)

Single microstrip antenna has the characteristics of narrow bandwidth and small gain. This paper discusses the design of a microstrip array antenna that works at two working frequencies, namely 2.4 GHz and 5 GHz for WiFi. The method used to obtain dual band frequencies is by adding slots on the side of the patch. The results obtained are the 4-element microstrip array antenna with feed line supply has better results when applied to WiFi. This feed line antenna has a bandwidth of 75 MHz - 184.4 MHz in accordance with IEEE 802.11n standards and has a gain of 4.321 dBi. Whereas the EMC supply has a large gain of 11.54 dBi but the bandwidth obtained is very narrow, namely 27.5 MHz.

Parametric Study and Analysis of Microstrip Patch Antenna with Multiple Slit Positions

Abstract Parametric study and analysis of microstrip patch antenna with multiple slit positions is presented in this research contribution. This work is aimed to design a microstrip patch antenna, which can able resonate dual-band frequencies (i.e. 3.5 GHz and 5.3 GHz) with a trade-off between the geometrical parameters. The proposed antenna designed using the multiple slits on the patch, RT Duroid 5880 as substrate material, and with a defected ground structure. Owing to the geometrical miniaturization this antenna will be capable to work at sophisticated communication systems where size of the communication system is a desired parameter.

Dual‐band CPW rectenna for low input power energy harvesting applications

A dual-frequency band low input power rectenna is proposed in this study. The rectenna is comprised of a co-planar waveguide (CPW) rectifier integrated with a rectangular split ring antenna loaded by a spiral strip line. A single diode series connection topology is used to miniaturise the losses at low input power. A spiral coil in addition to two short circuit stubs are used as a matching network for maximum power transfer between the antenna and the rectifying circuit. The proposed rectenna operates at low input power with relatively high measured RF-DC conversion efficiency up to 74 % at input power of − 6.5 dBm at the first resonant frequency f 1 = 700 MHz and 70 % at − 4.5 dBm at the second operating frequency f 2 = 1.4 GHz with a resistive load of 1.9 k Ω . The measured rectenna sensitivity (the rectenna ability to receive low power with acceptable conversion efficiency) reaches up to − 20 dBm with a conversion efficiency of 47 and 36 % at f 1 and f 2 , respectively, and a DC output voltage of 0.18 V . The measured efficiency is over 50 % from − 18 to − 3.5 dBm and from − 15 to − 1.5 dBm at f 1 and f 2 , respectively.

Co-design Structure of Dual-Band LNA and Dual-Band BPF for Radio Navigation Aid Application

In this paper, a co-design of a dual-band low-noise amplifier (DB-LNA) with a dual-band band-pass filter (DB-BPF) for a radio navigation aid (RNA) application was proposed. The novel development was that the DB-LNA was directly integrated with the DB-BPF instead of connecting the output matching network (OMN) of the DB-LNA to the 50 Ω-port of the DB-BPF. Thus, this DB-BPF had a double function, serving as the DB-BPF and also as the OMN. This architecture was called the co-design structure. ZIN analysis was used to evaluate the co-design network structure. In general, the design procedure was divided into four sections, including (1) DB-BPF, (2) DB-LNA, (3) Cascade DB-LNA and DB-BPF, and (4) Co-design DB-LNA and DB-BPF. The co-design method was applied in an RNA implementation at dual-band frequencies of 113 MHz and 332 MHz. Validation of the proposed structure is confirmed for its accuracy by simulating the impedance characteristic ZIN, S parameter simulation, and measurement results. The key contributions of this paper were that: (1) The co-design structure could reduce the passive component by 31.5%, (2) the total size of the DB-LNA and DB-BPF using the co-design method was smaller than the cascaded method by 11.36%, (3) more light-weight in fabrication due to a smaller size, and (4) finally, the proposed LNA has a higher figure of merit than the other LNA.

Design of wide band compact bend triangular resonator artificial magnetic conductor and its application for antenna gain enhancement

SummaryIn this paper, a compact bend triangular resonator (CBTR) structure is proposed as artificial magnetic conductor (AMC) to enhance antenna gain for wide frequency bandwidth. This paper presents the metamaterial properties of the CBTR structure like absorbance and reflection phase. The CBTR unit cell gives in‐phase reflection (0° ± 90°) for 55.2% bandwidth. The CBTR unit‐cell reflection phase analysis is presented for the different height of normal incident wave. The CBTR AMC performance is validated using a wideband dipole antenna. For −6‐dB impedance bandwidth, the standalone dipole antenna covers ultrawide frequency range 3.1–12 GHz and for −10‐dB impedance bandwidth, antenna has dual band frequency response 3.4–4.4 GHz and 8.3–11 GHz. The antenna shows good impedance matching and radiation characteristics for frequency range, where the unit‐cell reflection phase is 135° to 45° for frequency range 2.5–6.5 GHz (bandwidth of 88.8%). The broadside directivity of 7 dBi is achieved for the dipole antenna with CBTR AMC in the frequency range of 2.5–6.5 GHz and broadside gain of &gt;5 dBi in the frequency range of 3.2–6.7 GHz (bandwidth of 70.7%). The antenna efficiency of 60% (minimum) is achieved for the frequency range of 3.68.0 GHz (75.8%). The proposed CBTR design is orthogonally symmetric and is useful for dual‐polarized wideband frequency applications like wireless local area network (WLAN) (2.4–2.5 and 5.15–5.85 GHz) and new radio (NR) 5G sub‐6‐GHz (3.3–5.0 GHz).

Design and Investigation of a Miniaturized Single-Layer ACS-Fed Dual Band Antenna for LTE and 5G Applications

Presently, a single compact antenna is expected to operate in multiple frequency bands, so that it may be used for multiple applications. In this regard, a compact asymmetric coplanar strip (ACS) fed monopole antenna was designed to operate in LTE band-40 and 5G mid band frequencies. To achieve the desired dual band frequency, meander line radiating structure was used. The uniplanar design with the ACS feed considerably reduced the antenna size to 19.25 × 10.5 × 1.6 mm3. This miniaturized dual band antenna can be easily integrated into circuit boards. The measured and simulated results provided a reflection coefficient (S&lt;sub&gt;11&lt;/sub&gt;) &lt; –15 dB, which made the antenna suitable for LTE band-40 and 5G mid-band communication applications.

DESIGN OF DUAL BAND PATCH ANTENNA AT KU-BAND FOR WIRELESS APPLICATIONS

In this paper, U-shaped patch antenna with triangular stub antenna is proposed for satellite and radar applications. The U-shaped with triangular stub structure is considered on the patch antenna with symmetric feed is presented on the substrate. The antenna design is impressed on FR4_Epoxy substrate material whose dielectric constant is 4.4. The adopted antenna resonates dual band frequencies at 14.1049GHz and 15.1610GHz which are used for satellite communications and 16.9363GHz and 17.7903 GHz which are used for radar communications. The parameters of antenna like gain, reflection coefficient, radiation pattern and bandwidth are analyzed and presented in the results. The adopted design achieves gain of 5.18dB and reflection coefficient of -28.75dB at 14.1049GHz, gain of 3.79dB and reflection coefficient of -16.31dB at 15.1610GHz, gain of 3.40dB and reflection coefficient of -16.45dB at 16.9363GHz and gain of 4.17dB and reflection coefficient of -15.93dB at 17.7903GHz.

Indoor Localization System Using Dual-Frequency Bands and Interpolation Algorithm

As an important part of the Internet of Things, WiFi-based fingerprint indoor localization technology has been extensively studied due to the widespread deployment of WLAN in indoor environments. Nevertheless, there are two stubborn issues in indoor localization using the fingerprint method, one is the additional localization error caused by heterogeneous devices and the other is the huge time consumed by upgrading the fingerprint database. Here, we propose a dual-frequency difference and cubic spline interpolation (DFD-CSI) localization system in this article. First, according to the characteristics of commercial WiFi router generally supports 2.4- and 5-GHz dual bands, a fingerprint database is established using these two bands’ data and their difference data. The existence of difference solves the problem of device heterogeneity, while the existence of dual-frequency data makes the positioning result more robust. In addition, we also use cubic spline interpolation to upgrade the rough fingerprint database in order to reduce the time of site exploration on the premise of ensuring localization accuracy. Extensive experiments have been conducted in a campus hall. Results show that DFD-CSI is robust against altered devices and access points (APs) compared with the traditional heterogeneous devices algorithms and crowdsourcing update methods, achieving a mean error of 3.7 m and 27.5% localization error reduction with APs changed.