Dual-band Mode Research Articles

Semi-Automatic Design of Dual-Band End-Fed Antennas for Digital Antenna Arrays

Introduction. The topic of implementing a dual-band mode of operation for director dipole antennas is represented by a wide range of works, almost all of which are dedicated to studying the properties of a classic dipole. However, the issue of end excitation of radiators for dual-band director antennas remains open. The development of such radiators requires a deep analysis both from the point of view of developing mathematical and electrodynamics models, which corresponds to the tactical and technical requirements of modern digital antenna arrays.Aim. To substantiate a procedure for determining the initial appearance of a dual-band antenna exciter from the standpoint of the systems approach to the design of antenna elements and nodes. This procedure is suitable for a semi-automated design of more complex antenna systems.Materials and methods. As part of the research, the input impedance of a dual-band system consisting of two active radiators and two passive directors was determined using the method of induced electromotive forces (EMF). Models of dual-band director radiators were developed using the CST Studio Suite 2021 full-wave electromagnetic simulation.Results. The results of developing procedures for a semi-automatic design of antennas with a dual-band function of input impedance are presented. Following a comparative analysis, approaches to implementing the printed layout of an antenna comprising standard radio engineering components, which imply serial production, are proposed.Conclusion. The proposed models can be used when designing director, turnstile, and cardioid antennas, as well as antenna arrays. These designs are analogous to antennas based on a classic central excited dipole.

Novel Design of a Bandwidth Enhanced and Frequency Reconfigurable, Wearable Antenna for Body Centric Communication

This paper proposes a novel design for a frequency reconfigurable and bandwidth-enhanced antenna for use in biomedical telemetry applications. Data pertaining to a patient’s body parameters, such as blood pressure, pulse, and temperature, are gathered using sensors and then transmitted to a remote place for monitoring. The proposed antenna is connected to a wearable transmitter, which transfers the body parameter data to a centrally located nearby control unit. The antenna operates in the 5.8 GHz band in single-band mode and in the 4.27 GHz (C band) and 5.8 GHz industrial, scientific, and medical (ISM) bands in dual-band mode. The use of ethylene-vinyl acetate foam as a substrate makes the structure waterproof and ultraviolet resistant. The basic antenna structure equipped with proximity coupling offers a front-to-back ratio (FBR) of 17.62 dB and a bandwidth of 122 MHz. With an additional upper patch and resonant slots, bandwidth enhancement of 82.85% and 11.57% improvement in the FBR are achieved, respectively. Overall, a maximum FBR of 19.66 dB and gain of 5.0 dBi are attained over the resonant frequency. The specific absorption rate is found to be 0.145 W/kg for 10 gram of tissue.

Frequency reconfigurable two-element MIMO antenna for cognitive radio and 5G new radio sub-6 GHz applications

Abstract In this paper, a compact two-element reconfigurable multiple-input multiple-output (MIMO) antenna for 5G new radio sub-6 GHz is presented and discussed. The proposed MIMO antenna has four frequency operating modes: a wideband operating mode (2.41–6 GHz), a wideband operating mode with a notching band at 3.5 GHz (3.2–3.66 GHz), a low-pass filter mode that filters the higher frequencies with a wide operating band from 2.41 GHz to 4.7 GHz, and a dual-band mode with two operating narrow bands (2.41–3.16 GHz and 3.64–4.7 GHz). To improve the isolation over the entire operating band, a strip line connecting the two ground planes of the two antenna elements has been used. To validate the proposed approach, different prototypes have been fabricated and measured. The simulation results are in good agreement with the measurement results. The proposed antenna has good MIMO diversity performance with a maximum gain of 4.64 dBi. The minimum isolation is 18 dB for the four operating modes, while a measured envelope correlation coefficient of less than 0.008 is achieved. The diversity gain is near 10 dB for various operating modes. The antenna is suitable for cognitive radio and 5G sub-6 GHz applications.

Design of Compact Wideband/Bi-Band Frequency Reconfigurable Antenna for IoT Applications

This paper discusses the design and performance of a frequency reconfigurable antenna for Internet of Things (IoT) applications. The antenna is designed to operate on multiple frequency bands and be reconfigurable to adjust to different communication standards and environmental conditions. The antenna design consists of monopole with one PIN diode and 50Ω feed line. By changing the states of the diode, the antenna can be reconfigured to operate in a dual-band mode and a wideband mode. The performance of the antenna was evaluated through simulation. The antenna demonstrated good impedance matching, acceptable gain, and stable radiation patterns across the different frequency bands. The antenna has compact dimensions of (26×19×1.6) mm3. It covers the frequency range 2.95 GHz -8.2 GHz, while the coverage of the dual- band mode is (2.7-3.8) GHz and (4.57-7.4) GHz. The peak gain is 1.57 dBi for the wideband mode with omnidirectional radiation pattern. On the other hand, the peak gain of the dual-band mode is 0.87 dBi at 3 GHz and 0.47 dBi at 6 GHz with an omnidirectional radiation pattern too.

An OOK and Binary FSK Reconfigurable Dual-Band Noncoherent IR-UWB Receiver Supporting Ternary Signaling

This article presents a multiband low-power and low-complexity impulse radio ultrawideband (IR-UWB) noncoherent receiver. The proposed receiver can be digitally reconfigured in three different modes of operation, including two single-band modes and one concurrent dual-band mode. In the two single-band modes, the proposed envelope detection architecture is capable of receiving and demodulating an on–off keying (OOK) pulse stream at RF center frequencies of 2.8 or 4.8 GHz. In the concurrent dual-band mode, the proposed architecture is able to demodulate binary frequency-shift keying (FSK), in addition to OOK demodulation, at center frequencies of 3 and 5 GHz. The receiver is composed of a reconfigurable low-power differential low noise amplifier (LNA), a fully differential squarer (self-mixer circuit), low-pass filter (LPF), and variable gain baseband (BB) amplifiers. The receiver is fabricated in TSMC 130-nm CMOS process technology. The receiver can operate at up to 150 Mb/s with the ternary signaling that is enabled by the binary FSK modulation combined with the OOK modulation in concurrent dual-band mode. At its maximum gain, the receiver achieves a sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 72 dBm at a bit error rate (BER) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-3}$</tex-math> </inline-formula> at a 100-Mb/s data rate. It consumes 11.9 and 13.2 mW from a 1.2-V supply in the single-band modes and concurrent dual-band mode, respectively.

Compact dual-band rectangular T E10 mode to circular TM01 mode converter for telemetry/telecommand applications in satellite communication: design, equivalent circuit modeling, mode level measurement technique and 3d printed manufacturing

In this study, the design of a dual-band mode converter, which provides transition from rectangular waveguide T E10 mode to circular waveguide TM01 mode and operates simultaneously in telemetry/telecommand (TT&C) frequencies, is presented along with its equivalent circuit and a mode level measurement technique. This dual-band converter is designed to uniformly excite TT&C slot antennas used in satellite communication with symmetric circular TM01 mode. The structure can work as a transceiver due to having one common rectangular waveguide feed. As a Ku-band application, a converter giving high purity TM01 mode at circular waveguide at 11.75 GHz/TX and 13.75 GHz/RX center frequencies is designed and manufactured with 3D printing technology. Approximate equivalent circuit models of the designed structure are extracted by using lumped elements from simulated S-parameter results. In addition, a measurement technique to detect the normalized power levels of different propagation modes in dual-band mode converter is applied on the manufactured structures to obtain transmission levels of circular TM01 mode and suppression levels of circular T E11 mode. It is revealed from the measurement results that while the designed structure gives more than 17.5 dB return loss and suppression of T E11 mode, and less than 0.6 dB insertion loss of TM01 mode within 500 MHz bandwidth at TX band, it gives more than 23 dB return loss and suppression of T E11 mode, and less than 0.3 dB insertion loss of T M01 mode within 900 MHz bandwidth at RX band.

Field Trial of a Coherent, Widely Distributed, Dual-Band Photonics-Based MIMO Radar With ISAR Imaging Capabilities

Soon after its introduction in the communications domain, the novel concept of multiple input–multiple output (MIMO) has been making its way also into the radar world. A new generation of multistatic netted systems with unprecedented capabilities has been fully theorised, unveiling its potential advantages over its classical stand-alone, monostatic counterparts. However, MIMO radars mainly remained the object of abstract modeling, since electronic technology could hardly support the practical implementation of this new class of systems. With the development of microwave photonics, the realization of MIMO radar networks at the best of their capabilities has become a reality, thanks to the inherent coherence of photonics systems, and to the broad-band, low-distortion, and interference-immune optical signal distribution. This paper presents the results of a microwave photonics widely-distributed, dual-band MIMO radar network, deployed in a real freight port for maritime traffic monitoring, with inverse synthetic aperture radar imaging capabilities. It employs a central unit connected to multiple widely distributed remote radar peripherals thanks to optical fiber. The possibility to operate in dual-band mode, and the coherent management of the transmitted and received signals are demonstrated, exploiting geometric and frequency diversity in target detection. The system exhibits a spurious-free dynamic range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\sim 82}\,{\mathbf{d}\mathbf{B}\cdot \mathbf{\mathbf{Hz}}^{\mathbf{2/3}}}$</tex-math></inline-formula> and a sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf{-110}\,\mathbf{dBm}$</tex-math></inline-formula> . Under these premises, a small boat of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf \sim\! 1\,{\mathrm{\mathrm{m}}^{\mathrm{2}}}$</tex-math></inline-formula> radar cross section has been detected at more than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {800}\,{\mathbf{m}}$</tex-math></inline-formula> , achieving a probability of detection of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {0.85}$</tex-math></inline-formula> , for a false alarm rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {7.7\times 10^{-4}}$</tex-math></inline-formula> .

An X/Ku Dual-Band Switchless Frequency Reconfigurable GaAs Power Amplifier

This letter presents an <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>/ <i>Ku</i> dual-band switchless power amplifier (PA) with frequency reconfigurable operation in a 0.25-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> GaAs pHEMT process. The proposed reconfigurable PA consists of one dual-band drive amplifier and two single-band amplifiers in parallel. The first stage drive amplifier works in dual-band mode of <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>-band and <i>Ku</i>-band, and the two single-band amplifiers work in <inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>-band and <i>Ku</i>-band, respectively. An interstage coupled line is used to split the dual-band frequencies into high-band (<i>Ku</i>-band) and low-band (<inline-formula> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula>-band), and the output-stage coupled line acts as a combiner. The operating frequency band of the proposed PA can be changed by turning off drain voltages of unused single-band amplifiers. Measurements results show that the proposed reconfigurable PA features a maximum power-added efficiency (PAE) of 44.4&#x0025; and a power gain of 19.6 dB while delivering an output power of 29.6 dBm at 8.5&#x2013;9.5 GHz of the low-band mode. At 15.5&#x2013;16.5 GHz of the high-band mode, the PA achieves a maximum PAE of 38.4&#x0025;, a power gain of 18.1 dB with an output power of 30.1 dBm. The chip area of the proposed reconfigurable PA is 2 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 mm² including all RF and dc pads.

Bandwidth‐extended single‐input switchable Doherty power amplifier based on dual compensating reactance with adjusted drain voltage

This study presents a switchable Doherty power amplifier (S-DPA) based on dual compensating reactance and adjusted drain voltage with 124% fractional bandwidth (FBW) using single-input architecture. The proposed S-DPA can be operated in wideband mode (WB-MOD) and dual-band mode (DB-MOD) with a larger power back-off region through one-click switching directly. The needed back-off impedance in both operation modes is achieved by using the dual compensating reactance for bandwidth extension. Meanwhile, a load modulation enhancement technique through adjusting the drain voltage of both the carrier and peaking amplifiers is proposed for proper load modulation in DB-MOD. To verify the proposed techniques, an S-DPA was designed and fabricated. Measurement results show that the proposed S-DPA has an efficiency of 51.3%–70.3% at saturated power of higher than 43.4 dBm over the frequency band of 0.8–3.4 GHz with 124% FBW. The 6-dB back-off efficiency in WB-MOD (1.3–2.9 GHz) is 45.3%–56.1% and the 8-dB back-off efficiency in DB-MOD (0.8–1.3 GHz & 2.9–3.4 GHz) is 41.6%–57.9%. 80-MHz modulated signals with 6.2-dB and 8.2-dB peak to average power ratios are used to evaluate the modulated signal performance in two modes. The DPA can achieve an average efficiency of up to 56% with high linearity after digital pre-distortion linearisation.

Switching plasmonic resonance in multi-gap infrared metasurface absorber using vanadium dioxide patches

Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band modes, adaptive wind-driven optimization was employed as a global optimization technique. The proposed absorber provides polarization-independent behavior for both Transverse Electric and Transverse Magnetic polarizations. Moreover, the proposed design shows above 80% absorptance for incidence angle up to 45° for the dual-band mode, and up to 35° for the single-band mode. When operating the absorber as a tunable emitter, a switching of 79% in emissivity is achieved at 8.25 μm. These favorable findings may facilitate the development of important devices for temperature regulation, smart windows, and thermal imaging.

Asynchronous Chirp Slope Keying for Underwater Acoustic Communication

We propose an asynchronous acoustic chirp slope keying to map short bit sequences on single or multiple bands without preamble or error correction coding on the physical layer. We introduce a symbol detection scheme in the demodulator that uses the superposed matched filter results of up and down chirp references to estimate the symbol timing, which removes the requirement of a preamble for symbol synchronization. Details of the implementation are disclosed and discussed, and the performance is verified in a pool measurement on laboratory scale, as well as the simulation for a channel containing Rayleigh fading and Additive White Gaussian Noise. For time-bandwidth products (TB) of 50 in single band mode, a raw data rate of 100 bit/s is simulated to achieve bit error rates (BER) below 0.001 for signal-to-noise ratios above −6 dB. In dual-band mode, for TB of 25 and a data rate of 200 bit/s, the same bit error level was achieved for signal-to-noise ratios above 0 dB. The simulated packet error rates (PER) follow the general behavior of the BER, but with a higher error probability, which increases with the length of bits in each packet.

A Hybrid Mutual Coupling Reduction Technique in a Dual-Band MIMO Textile Antenna for WBAN and 5G Applications

This paper presents a hybrid mutual coupling reduction technique applied onto a dual-band textile MIMO antenna for wireless body area network and 5G applications. The MIMO antenna consists of two hexagonal patch antennas, each integrated with a split-ring (SR) and a bar slot to operate in dual-band mode at 2.45 GHz and 3.5 GHz. Each patch is dimensioned at $47.2 \times 31$ mm2. This hybrid technique results in a simple structure, while enabling significant reduction of mutual coupling (MC) between the closely spaced patches (up to $0.1\lambda$ ). This technique combines a line patch and a patch rotation technique, explained as follows. First, a line patch is introduced at an optimized distance to enable operation with a broad impedance bandwidth at both target frequencies. One of the patches is then rotated by 90° at an optimized distance, resulting in a significant MC suppression while maintaining the dual and broad impedance bandwidth. The proposed MIMO antenna is further evaluated under several bending configurations to assess its robustness. A satisfactory agreement between simulated and measured results is observed in both planar and bending conditions. Results show that the MIMO antenna achieves an impedance bandwidth of 4.3 % and 6.79 % in the 2.45 GHz and 3.5 GHz band, respectively. Moreover, very low MC ( $S_{21} dB) is achieved, with a low ( $x$ - and $y$ -axes, the antenna bent maintained a realized gain of 1.878 dBi and 4.027 dBi in the lower and upper band, respectively. A robust performance is offered by the antenna against the lossy effects of the human body with good agreements between simulated and measured results.

Design of a multimode tunable low noise amplifier for software defined radios

This Letter presents the design and analysis of a tunable low noise amplifier (LNA) capable of achieving single band, dual band and wideband operations. The circuit features a modified tunable open stub matching to achieve a reconfigurable multiband response. The LNA adopts a varactor diode in the input matching stage to achieve reconfigurable modes. Two bias conditions for the varactor diode are analysed. The forward bias condition yields a wideband mode (1.6 to 2.5 GHz) and zero bias results in a concurrent dual band mode (0.9 and 1.7–2.5 GHz). In reverse bias condition, the bias voltage of varactor diode () can be tuned to achieve one single band mode (1 GHz), and a tunable concurrent dual band mode, where the first band is fixed at 1 GHz and the second band is continuously tunable from 1.7 to 2.5 GHz. The LNA is fabricated in microwave integrated circuit process on an FR-4 board. The measured power gain is 7–15 dB and noise figure is 1.2–2.2 dB across all bands. The measured 1 dB compression () is , and at 0.9, 1 and 2.4 GHz, respectively.

A Compact Dual-Band Mode Converter for High-Power Microwave Applications

To realize multiband mode conversion in the high-power microwave (HPM) application system, a novel compact dual-band mode converter based on a universal method is proposed in this article. The proposed converter has a hybrid circular-embedded coaxial structure, and it integrates the conventional plate-inserted coaxial TEM-TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> converter and serpentine circular TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> -TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> converter simultaneously. Its outer and inner waveguides have the same curvature distributions along a longitudinal direction. Both the numerically calculated results and simulations exhibit that its maximum conversion efficiencies at two central frequencies are over 99% with a structure length of 240 mm. Simulated results indicate that the bandwidths reach 390 MHz (at X-band) and 4.2 GHz (at Ka-band), respectively, when the conversion efficiencies are over 95%. A prototype is fabricated and measured. The far-field results demonstrate that coaxial TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and circular TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> modes with high purity are detected at the output port of converter, and the S-parameter measurements illustrate that high conversion efficiencies at 8.4 and 30.5 GHz are obtained. The measurement results have a good agreement with the theoretical predictions and simulations.

Analysis and design of a novel concurrent Class B/J continuum power amplifier

In this paper, a novel concurrent Class B/J continuum mode is presented based on waveform shaping of current and voltage. The behavior characteristics and performances of power amplifiers (PAs) in concurrent dual-band mode are investigated in detail. According to the analysis of proposed concurrent mode, the optimal load impedances at fundamental, harmonic and intermodulation (IM) frequencies are related to the magnitude ratio of the two carriers. Comparing with concurrent Class-B mode, two parameters α, β can be configured independently in the proposed concurrent mode, which provides more freedom and flexibility for design without output power and drain efficiency degradation. In order to verify the proposed theory, a 1.9/2.35 GHz dual-band power amplifier based on proposed concurrent mode is designed, fabricated and measured. Experimental results show that when the PA is driven by two 10 MHz LTE signals concurrently with total 9.2 dB peak-to-average power ratio (PAPR), the total average power is 36.0 dBm with 40.6% drain efficiency, which indicates a good concurrent performance.

Design of a dual band dual mode antenna for on/off body communications

AbstractA dual band dual mode patch antenna for on/off body communications is proposed in this letter. The antenna operates at 2.45 and 5.8 GHz with different radiation modes. The radiation pattern is omnidirectional at the lower frequency band while directional in the broadside at the higher frequency band. Through introducing a ground plane below the radiating patch, the influence of the human body on the performance of the proposed antenna is minimized and the specific absorption rate value is significantly reduced and is much lower than the standard limit value.

Analysis and design of a novel dual-band coaxial waveguide mode converter for high-power microwave applications

ABSTRACTBased on the derived coupling coefficients of the circular waveguide and coaxial waveguide, a novel dual-band serpentine coaxial mode converter is proposed in this paper. This dual-band converter consists of two parts: an inner inserted circular waveguide TM01-TE11 converter operating at Ka-band, and an outer coaxial waveguide TEM-TE11 converter working at Ku-band. The inner and outer converters have the same curvature distribution along the propagation direction with a structure length of 800 mm. Simulated results exhibit that the maximum conversion efficiencies of the inner and outer converters reach 98.7% and 98.9% at 35 and 15 GHz, respectively. The bandwidths of the inner and outer converter are 1.9 and 2.5 GHz when the conversion efficiency is over 90%. Furthermore, the dual-band mode converter has a symmetry and reciprocity structure with coaxial-parallel input/output port. The good agreement between theoretical calculations and simulation demonstrates the feasibility of this design.

Design of Concurrent Dual-Band Continuous Class-J Mode Doherty Power Amplifier With Precise Impedance Terminations

In this letter, a novel methodology for designing concurrent dual-band continuous class-J mode Doherty power amplifier (DPA) with precise impedance terminations is presented. First, the required impedance condition of the carrier amplifier which operates in continuous class-J mode at the back-off region is analyzed in detail. Based on the proposed theory, the fundamental impedance is realized by taking advantage of the noninfinity output impedance of the peaking stage, then the second harmonic impedance is realized with a harmonic tuning postmatching network. A 1.8-/2.6-GHz dual-band DPA employing commercial GaN devices is designed and implemented to validate the proposed method. The fabricated DPA can achieve 68.5% and 75% drain efficiencies (DEs) for saturated power level at 1.8 and 2.6 GHz, respectively. For the 6-dB back-off region, the measured DEs are 64% and 63% at the two designed frequencies.

Volterra series-based model for concurrent dual-band power amplifier using dynamic memory depth

In this article, a dynamic dual-band baseband equivalent Volterra (DDBE) model is proposed to compensate the nonlinear distortions of the concurrent dual-band power amplifier (PA). The DDBE model is obtained by improving the discretized dual-band baseband equivalent Volterra model which can describe the output characteristics of concurrent dual-band PA completely in theory but is lack of practicability. Three simplification rules are proposed in the article, and the relevance between in-band intermodulation and in-band cross modulation is employed to simplify the establishment complexity of the model. Then the dynamic kernels are categorized into three groups, and based on this, DDBE models with different level dynamical kernels are derived. In addition, draw on the experience of single-band PA behavioral model, even-order kernels are introduced into DDBE models. Digital predistortion performances of a wideband PA, which works in concurrent dual-band mode, are evaluated to verify the feasibility and advantages of the proposed model.

Coplanar Stripline Loaded Reconfigurable Loop Antenna for WLAN and WiMAX Applications

In this paper, a loop antenna loaded with coplanar strip (CPS) line is proposed as a multiband antenna. The CPS line is added with two switches to vary the antenna perimeter to cover seven different bands. The CPS line introduced into the loop is not only useful in reconfiguring antenna dimensions but also provides stationary radiation patterns for the all the covered bands. The proposed antenna works in single and dual-band modes. When the proposed antenna works as a single band antenna, it produces a band from 4.2GHz to 5.7GHz. Under dual-band operation, it produces bands from 3.75GHz to 4.7GHz and from 6.4GHz to 7.8GHz. The other dual-band mode ranges from 3.5GHz to 3.8GHz and from 5.58GHz to 7.4 GHz. The simulated and measured results are in good agreement and the proposed antenna can be used satisfactorily for W-LAN and WiMax applications. The proposed technique can also be used for size reduction of loop antennas.