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Analog photonic solutions offer unique opportunities to address complex computational tasks with unprecedented performance in terms of energy dissipation and speeds, overcoming current limitations of modern computing architectures based on electron flows and digital approaches. The lack of modularization and lumped element reconfigurability in photonics has prevented the transition to an all-optical analog computing platform. Here, we explore, using numerical simulation, a nanophotonic platform based on epsilon-near-zero materials capable of solving in the analog domain partial differential equations (PDE). Wavelength stretching in zero-index media enables highly nonlocal interactions within the board based on the conduction of electric displacement, which can be monitored to extract the solution of a broad class of PDE problems. By exploiting the experimentally achieved control of deposition technique through process parameters, used in our simulations, we demonstrate the possibility of implementing the proposed nano-optic processor using CMOS-compatible indium-tin-oxide, whose optical properties can be tuned by carrier injection to obtain programmability at high speeds and low energy requirements. Our nano-optical analog processor can be integrated at chip-scale, processing arbitrary inputs at the speed of light. All-optical platforms hold potential for fast and efficient analog computing, but are limited by their size and poor reconfigurability. Here, a zero-index nanophotonic platform enables post-Moore’s law analog optical computing, processing data with high throughput and low-energy levels.

In this paper, a fully synthesizable all-digital transmitter (ADTX) is first proposed. This transmitter (TX) uses Cartesian architecture and supports wide-band quadratic-amplitude modulation with wide carrier frequency range. Furthermore, the design methodology for ADTX and corresponding bandpass filter is discussed. This TX is synthesized with digital register transfer level-graphic database system flow, and can be easily implemented in any standard CMOS technology. An exemplary TX is synthesized by TSMC 28-nm standard cell library with extremely small area (0.0009 mm2) and supports carrier frequency as high as 6 GHz with excellent error vector magnitude (

In this paper, series feed networks based on composite right/left-handed transmission line for dual-polarized frequency scanning phased array antenna are presented. The proposed all-passive feed networks provide unique frequency dispersion and adjustable current amplitude distribution, which enable continuous backward-to-forward beam scanning capability as well as the directivity, beamwidth, and sidelobe level controllability of the incorporated array antenna. The working mechanisms are demonstrated through broadband dual-polarized aperture-coupled antenna elements and series feed networks that support uniform/binomial current amplitude distributions. Backward-to-forward frequency beam scanning and wide range beam shaping capability for dual-polarization states of the proposed phased array are validated in both simulation and measurement.

Novel 2-D gray-scale inkjet printed microstrip line (MSL) terminations are presented in this paper. The proposed open-end type MSL termination is constructed of a lossy trace printed on paper and placed on a typical dielectric substrate with background. Optimal design guidelines are also discussed for attaining best absorption band given ink resistivity and termination size. Both fixed width and tapered width lines are presented, experimentally showing high absorption levels over a wide bandwidth. These simple to fabricate structures may find applications in scenarios where low-cost wideband planar terminations are needed.

Impulse response of energy-efficient multiband RF-interconnect (MRFI) is analyzed to quantify its information capacity for transmitting digital data via various types of physical wires. Our analyses in frequency domain (also transferrable to time domain if needed) indicate that a baseband-equivalent impulse response can be established for MRFI under coherently communicated systems. We can further express such response in an explicit form for MRFI with low-pass transmission nature. It also reveals its distinct capability in signal equalization as a result of its RF-carrier down-conversion process. Furthermore, the analysis offers a guidance of how to construct baseband-equivalent impulse response when transmission lines contain non-ideal effects such as frequency notches and in-band ripples.

A multiharmonic absorption circuit utilizing the quasi-multilayered striplines is presented. The circuit consists of a multiharmonic reflection filter, a broadband bandpass filter, and a termination. The novel quasi-multilayered striplines, which consist of alumina substrates stacked using solder balls, provide flexibility in the filter structure and realize low insertion loss at the fundamental frequency. The measured results of the fabricated filter exhibit an insertion loss of less than 0.47 dB at the fundamental operation frequency in C-band, as well as high absorption of the second, third, and fourth harmonics, thus outperforming existing solutions. In addition, the device is compact, with a size of only 0.21 λ 0 × 0.39 λ 0 , where λ 0 is the free space wavelength at C-band.

Wireless transmission over 15Gb/s data rate is reported using space diversity MIMO. Multi-diversity planar antennas are designed and fabricated to transmit and receive the radio frequency signal simultaneously in 2 radiation diversities. Reliable 15Gb/s indoor data transmission over 5m distance is demonstrated in the super high frequency band (SHF) of 11.6GHz to 20.4GHz. Low BER is achieved with 2×2 MIMO space time block coded OFDM modulation.

We demonstrate the first silicon photonics enabled hyper-wideband wireless link with an instantaneous bandwidth of 12 GHz, which is 85% of the center frequency of 14 GHz. The silicon photonics based RF receiver consists of a four-channel optical phase encoder, an integrated hybrid-silicon mode-locked laser, and two silicon ring notch filters. The received CDMA RF wireless signal is correlated to baseband using coherent optical heterodyne at a data rate of 3 Gbps error-free with electronics bandwidth of only 3 GHz. Hyper-wideband RF transmission allows for data obfuscation and increased jamming resistance from narrowband interferers. The narrowband silicon photonic ring filters allow for further interference rejection of greater than 27 dB tunable over the full 20 GHz of RF spectrum.

This paper presents a millimeter-wave (125GHz) based ultra-short distance (∼2mm) contactless wave-connector (CWC) for consumer interconnect applications. Conventional high-speed connectors in interconnect standard such as USB, HDMI, DP, and Thunderbolt are not only expensive, but also suffer poor performance in both mechanical reliability and signal integrity often becoming a bottleneck in high-performance computing systems. The proposed CWC exploits a 125GHz CMOS transmitter (TX), receiver (RX), and compact FR4 PCB antenna to realize high-speed (>10Gb/s), low-cost, and energy-efficient connector solutions. An on-off keying (OOK) modulation is utilized for a non-coherent transceiver (TRX) architecture. In addition, antennas are designed on an FR4HR substrate for a compatibility with an existing infrastructure. The CMOS TX and RX is assembled with the antenna through a flip-chip process. The demonstrated CWC draws a total of 60mW of power under 1.1V supply while transferring 14Gb/s of data rate, achieving 4.28pJ/bit energy efficiency.

Multiplexers based on isolation circuits made of metamaterial lines are proposed and studied. The new approach provides unique advantageous features beneficial to system designer. For instance, there is no need to modify the filters used in multiplexers. Also, the design process is straightforward. In this paper, two types of multiplexers based on metamaterial isolation circuits are presented, and their operation concepts are explained. Also, theories and design process of isolation circuits are presented to help readers design and fabricate proposed multiplexers. For verifying the concepts, two types of triplexers and two types of quadruplexers are designed and fabricated. All filters used in the multiplexers are commercial surface acoustic wave filters. The measured results are well matched with the simulation results.

A new microstrip diplexer for ultra-wide-band (UWB) and wireless LAN (WLAN) bands is presented in this paper. The proposed structure integrates a multipole directional filter operating at WLAN band coupled to a UWB filter. The prototype is capable of processing the whole UWB region (from 3.1 to 10.6 GHz) with the WLAN band notch in one channel, and the passband WLAN band in other channel with a good selectivity due to the presence of transmission zeros at both sides of the WLAN band. The proposed diplexer is simple to fabricate, as it is designed using planar microstrip technology, and presents compact dimensions, making use of a low number of elements. Moreover, it presents the capacity of processing a narrow band (WLAN with 8% bandwidth) with a wide band (UWB). Simulated and measured results are presented with good agreement and the diplexer presents a good performance up to 15 GHz.

A wideband pattern diversity antenna operating at 5.5 GHz is proposed. The antenna is a monopole radiating element with two orthogonal feeds. The antenna has a bandwidth of 90%, over which the radiation patterns are consistent. A broadband phase shifting network is integrated with the antenna. Single pole double throw (SPDT) switches are used with the phase shifting network to electronically control radiation pattern of the antenna. Consistent diversity performance is achieved in terms of the radiation pattern by the integrated system over the entire bandwidth as that of the antenna.

A methodology to control the frequency transmission zeroes (FTZs) of a dual-mode resonator based elliptic-response filter is presented. Varactor loaded feeding structures are introduced for exciting a stub-perturbed ring-resonator to control the external quality factors associated with even and odd modes of the resonator. The technique allows for control of FTZs on either sides of the passband without any significant change in the bandwidth or operating frequency of the filter. Because of the high-Q nature of ring resonator, assymetric frequency responses are achieved with an in-band insertion loss 55 db at 190 MHz from the center-frequency of 2.2 GHz. Additionally, the filter is provided with tunable source-load coupling to isolate the movement of two FTZs.

This paper describes a branch line coupler using novel periodically grounded slow-wave transmission line (PG-SW-TL). The slow-wave characteristics is achieved by periodically placed through-via-holes (TVH). Compared with conventional cross-tie SW-TL, the proposed transmission line is easy to implement as a branch or a bend. In addition, it is easy to manufacture as it does not require blind-via-hole (BVH). The measurement results of the fabricated branch line coupler using PG-SW-TL for L-band demonstrate reducing 50.3 % of area.

Metamaterials are materials typically engineered with novel or artificial structures to produce electromagnetic properties that are unusual or difficult to obtain in nature. Because of their promise to provide engineerable permittivity, permeability, and index of refraction, metamaterials have drawn broad interest and have led to possible utilization in many electromagnetic applications from the microwave to optical regime, especially for the radiated-wave devices. This paper presents a detailed review upon the most recent research efforts associated with those metamaterial-based small antennas. They are discussed and classified in several different categories such as the antennas based on dispersion engineering, metaresonators, and metamaterial loadings. Some practical difficulties or limitations for the development of metamaterial-based small antennas are pointed out and the possible approaches to resolve these problems are also illustrated. A wide variety of antenna examples are included to facilitate the understanding for general readers.

A dual-band, all-passive phased-array feed network using composite right/left-handed (CRLH) dispersive lines is presented. This single feed network provides phase advance in addition to phase delay, which allows dual-band operation capable of directing the radiated beam to arbitrary directions. A simple design guide for a dual-band CRLH-based phased array is provided, and the array's performance is verified experimentally. The simulated and measured results show good agreement. This proposed array network is compatible with any type of conventional dual-band antennas.

In this paper, we propose and develop a partially shielded tunable filter structure using a varactor-loaded split-ring resonator. The novel physical topology of the filter is suitable for vertical stacking of filters and enables a compact multilayer tunable filter for applications requiring a very wide tuning range. The capacitance range and ratio needed to achieve the designated tuning range are presented, and analytical solutions are given for the second and third higher order modes for synthesis in the spurious-free filter operation range. Two prototypes are developed. A partially shielded tunable filter using varactor-loaded split-ring resonators is developed to verify the design method and to demonstrate the wide tuning range of a tunable filter. To further extend the tuning range, a filter bank with three stacked tunable filters at different frequency bands are designed and developed. With slight overlap between neighboring bands, a continuous tuning range of more than 6:1 is achieved.

Novel and compact composite right/left-handed (CRLH) quarter-wave type resonators are proposed in this paper. The resonator can resonate at the frequency where the electrical length is phase-leading or negative, which results in a smaller size as compared to the conventional phase-delayed microstrip-line resonator. Furthermore, it is only half the size of the CRLH half-wave resonator resonating at the same frequency. In addition, the proposed resonator is capable of engineering the multiresonances very close to each other, which makes it suitable to implement the miniaturized multiband microwave components such as diplexers and triplexers. A very compact diplexer and a very compact triplexer are proposed based on the proposed CRLH quarter-wave resonators in this paper and both of them have demonstrated very good performance. Specifically, compared to the referenced works based on the conventional microstrip resonators, the proposed diplexer and triplexer are 50% and 76% smaller than their microstrip counterparts, respectively.

Design formulas of symmetric and asymmetric dc blocks are presented for achieving Chebyshev and Butterworth frequency responses. They can also be used for impedance transformers. Design formulas of symmetric dc blocks are first derived and those of asymmetric dc blocks are also computed based on the symmetric ones. For easy derivation of design formulas of the symmetric dc blocks, coupling coefficient, being proportional to bandwidth, is defined. It is then clarified that symmetric Chebyshev dc blocks are not possible for the impedance transforming. For the symmetric Butterworth dc blocks, three design methods are exploited. To verify the symmetric Butterworth dc blocks, a microstrip dc block with 50- and 25-Ω termination impedances designed at a center frequency of 2 GHz was fabricated. The measured S12 = S21 and S11 = S22 are - 0.19 and - 57 dB around 2 GHz, showing quite good agreement with simulation results. Based on synthesized symmetric dc blocks, the coefficients of transfer function |S12|2 are calculated and design formulas of the asymmetric dc blocks are derived based on the symmetric ones. Asymmetric Chebyshev dc blocks are verified by the measurements provided in a previously published paper and asymmetric Butterworth dc blocks by the symmetric Butterworth dc block measured in this paper.

In this paper, a resonator based on composite right/left handed transmission line concept is discussed. This resonator excites -1st order resonance mode. We start with half-wave resonators consisting of two unit cells of a composite right/left handed transmission line. From the simulated field distributions, the center of these half-wave resonators can be short-circuited to obtain a quarter-wave resonator in the -1st mode. Susceptance slope parameters are calculated for the resonator. Then this resonator is applied for a 2-pole filter made by LTCC, which can be designed with standard filter design theory owing to the slope parameter. The dimension of the experimental filter implemented by LTCC is 2.5mm by 1.35mm by 0.52mm. The insertion loss is 1.80dB at the 2.4GHz band. Good agreement between measured and computed results is obtained.

In this paper, the feasibility of composite right/left-handed transmission lines for realizing proximity coupled interconnects is reported. The proposed interconnects' resonant length can be miniaturized due to the zeroth order resonance supported by a composite right/left-handed transmission line resonator. In addition, the proposed interconnects can achieve broadside coupling because the zeroth order resonance occurs in the fast-wave region. Simulated and measured electric field distributions are shown to explain the broadside coupling phenomenon. To validate the arbitrary size and broadside coupling of the proposed interconnects, simulated and measured transmission characteristics are presented. The results show that low insertion loss can be achieved by using single and double broadside coupling between interconnects.

Direction-of-arrival (DOA) estimation in a phased-array system is considered for a non-Gaussian noise environment. In this paper, a robust M-estimation scheme based on Huber's loss function with an adaptive threshold is proposed. The method is evaluated using experimental data from the University of California, Los Angeles, 60-GHz antenna-array system. It is shown that the proposed method enables a decreased sensitivity of the DOA estimates with respect to noise components having heavy-tailed distributions.

Retrodirective arrays have shown great potential for use as wireless transponders due to their automatic source tracking ability. A retrodirective transponder based on a sparse array is presented. The architecture uses a sparse array design to reduce the amount of elements, and thus circuitry required. A genetic algorithm is used to determine the optimal element positions in the array. The sparse architecture is compared with the uniform array architecture. Measured results verify the sparse concept as well as retrodirectivity

A retrodirective array with adaptive interference rejection is developed to introduce additional functionality to conventional retrodirective arrays. This is the first retrodirective array to present an interference rejection mode, creating a secure wireless communication link. The array uses digital signal processing initially and periodically to determine the location of a jamming signal and directs sub-arrays to form a null in the corresponding direction. The continuous analog self-tracking of a desired source maintains the retrodirective array's high-speed advantage over conventional smart antennas, requiring no computational algorithms for direction of arrival estimation and beamforming. It is demonstrated that interference is highly detrimental to retrodirective array performance, validating the need for such interference rejection. The application of this architecture is verified through a link test analyzing the reception and transmission of modulated data.

This paper presents a 2.12-GHz GaAs FET dual-operation-mode amplifier with a new efficiency-enhancing technique that employs novel switchable 1:1/1:0 ratio power-routing schemes. The amplifier switches its operation, depending upon a required power level, to either a low-power or high-power mode. The integrated power routers enable all matching requirements in both modes to be satisfied regardless of the operating condition of the reference amplifiers. The measurement results show an improved efficiency performance in a low-operation power range, as compared to a conventional balanced amplifier, due to the power-routing schemes and demonstrated dual-mode operation. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 41–44, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21075

An experimental demonstration of transparency in the epsilon-negative (ENG) and mu-negative (MNG) pair using the composite right/left-handed transmission line (CRLH-TL) is presented. An eight-cell 1D microstrip transmission-line structure consisting of a ladder network of four CRLH unit cells with MNG characteristics connected to a ladder network of four CRLH unit cells with ENG characteristics is fabricated and tested. The transparency resulting from the cascading of MNG unit cells with ENG unit cells is observed in the S-parameter measurements and a circuit simulation of the voltage distribution. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 476–481, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21022

Metamaterials are artificial structures that can be designed to exhibit specific electromagnetic properties not commonly found in nature. Recently, metamaterials with simultaneously negative permittivity (/spl epsiv/) and permeability (/spl mu/), more commonly referred to as left-handed (LH) materials, have received substantial attention in the scientific and engineering communities. The unique properties of LHMs have allowed novel applications, concepts, and devices to be developed. In this article, the fundamental electromagnetic properties of LHMs and the physical realization of these materials are reviewed based on a general transmission line (TL) approach. The general TL approach provides insight into the physical phenomena of LHMs and provides an efficient design tool for LH applications. LHMs are considered to be a more general model of composite right/left hand (CRLH) structures, which also include right-handed (RH) effects that occur naturally in practical LHMs. Characterization, design, and implementation of one-dimensional and two-dimensional CRLH TLs are examined. In addition, microwave devices based on CRLH TLs and their applications are presented.

A retrodirective array capable of full duplex communication is presented. The system is based purely on analog circuits for all signal-processing tasks including target tracking, beam pointing, and carrier recovery. Two types of receiver architectures are used, i.e., AM diode detectors for near-omni directional coverage and a digital beamforming receiver to enhance signal-to-interference ratio. This paper also discusses this technology in the context of development of a radar target/communication device, which is intended to both facilitate radar imaging and establish a self-tracking communication link between the ground terminal and mobile radar station. Demonstration of 10-Mb/s data receiving and transmitting functions are presented along with its automatic beam-steering ability and radiation patterns, as well as details about each major circuit component used in the array.

A new method for reducing mutual coupling in a smart antenna array using patch antenna elements is proposed. In a recently introduced smart antenna architecture, the spatial multiplexing of local elements (SMILE) scheme, the newly proposed array feed network affects mutual coupling. It is demonstrated that proper design of the feed network may reduce mutual coupling significantly, yielding nearly ideal radiation characteristics. Numerical solutions are used to study and optimize the currents on the surface of a four-element C-band patch antenna array and feed network. Radiation patterns of the same array with different feed networks are also computed. Results show a reduction in sidelobe level of several decibels, increased accuracy in beam pointing during scan, and improved null depth and placement.

Evolutionary generation of three-dimensional microwave line-segment circuits embedded in a multilayer structure is presented. Connections of the line segments and their lengths are expressed by sets of parameters, which are evolutionarily optimized by the genetic algorithms. Practical optimization time is achieved by introducing models of broadside-coupled multiconductor transmission lines instead of full-wave electromagnetic (EM) calculations. The scattering parameters of the models are connected with the scattering parameters of vias, and are synthesized into that of the whole circuit. Using line segments, we can obtain not only small components for limited-space applications, but also large components for wide-band frequency specifications without increasing computational complexity. Two bandpass filters and a bandstop filter were designed and tested by an EM simulator. The bandpass filters were also fabricated and measured. The results validated our proposing procedure.

A wireless sensor server is developed based on a reconfigurable active smart-antenna/retrodirective array. The system can serve as both a retrodirective array transponder and a smart-antenna receiver simply by changing the frequency of the local oscillator applied to the mixers, enabling it to utilize its hardware best to suit its communication environment. When operating as a direct-conversion receiver, the receiver array successfully demodulates a quaternary phase-shift keying (QPSK) modulated signal with circuit gain of 7 dB, and E/sub b//N/sub 0/ for BER=10/sup -4/ is approximately 12 dB without any error correction. In the retrodirective array mode, the system provides 20 dB circuit gain and 20 dB radio-frequency/intermediate-frequency isolation at the center frequency as well as phase conjugation, exhibiting excellent retrodirectivity. The mixers perform phase conjugation and modulation simultaneously, enabling the transmission of locally stored data. The local data is successfully extracted by an interrogator.

Antenna arrays are individual radiating elements combined so that they function and perform like a single large antenna. Besides high radiating beam directionality, antenna arrays offer the capability to scan the main beam and control sidelobe radiation electronically. Retrodirective antenna arrays, as the name suggests, have a special feature. When receiving a signal from an unspecified direction, the array can automatically transmit a signal response to that same direction without any previous knowledge of the source direction. This function is performed automatically without the use of phase-shifters or digital circuitry. Compared to other array antennas that rely on digital signal processing (DSP) for beam direction control, this approach is much simpler and potentially faster because digital calculation is not needed. The automatic beam control nature of retrodirective arrays is well suited for RFID (radio frequency identification) and microwave tracking beacon applications. The article discusses the basic functionality as well as the ongoing research efforts and developments in retrodirective array architectures. Self-phasing attributes of different arrays are presented, as well as their applicability in practical communication systems.

A new type of smart antenna array receiver with adaptive beamforming is proposed. The novel system offers a drastic reduction in hardware requirements for the smart antenna system through the use of a new Spatial Multiplexing of Local Elements (SMILE) scheme. In this scheme, a single element of the array is sequentially connected to signal processing circuitry in order to sample the incoming modulated carrier. The sampling rate is higher than the signal bandwidth so that the information of the original signal can be fully restored in the post stages using low-pass filters. This system offers an N times reduction in RF hardware for an N-element array. A four-element prototype is built. System principles, SNR, advantages, and hardware, including a new type of array feed network, are discussed. The system performance is validated through a link test with digitally modulated data.

This paper proposes an extension of the unconditionally stable finite-element time-domain (FETD) method for the global electromagnetic analysis of active microwave circuits. This formulation has two advantages. First, the time-step size is no longer governed by the spatial discretization of the mesh, but rather by the Nyquist sampling criterion. Second, the implementation of the truncation by the perfectly matched layers (PML) is straightforward. An anisotropic PML absorbing material is presented for the truncation of FETD lattices. Reflection less than -50 dB is obtained numerically over the entire propagation bandwidth in waveguide and microstrip line. A benchmark test on a microwave amplifier indicates that this extended FETD algorithm is not only superior to finite-difference time-domain-based algorithm in mesh flexibility and simulation accuracy, but also reduces computation time dramatically.

A novel design of smart antenna system with adaptive beamforming capability is introduced for broad-band wireless communication. To achieve high data throughput of the multi-antenna system, a parallel analog-digital (A/D) signal processing scheme is proposed. The essential idea is to realize the real-time beamforming using heterodyne RF and IF circuitry. The bottleneck of digital signal processor (DSP) I/O and processing speed is thus relieved, while the advanced signal processing capability of the DSP chip is utilized. Based on this idea, a 5.8 GHz smart antenna receiver is implemented. Various experiments are carried out to examine the direction of arrival (DOA) estimation, beam synthesis, and bit error rate (BER) performances of the system. A 20-Mb/s data throughput using binary phase shift keying (BPSK) modulation is demonstrated for this eight-element adaptive array.

This article reports the recent progress in active and passive retrodirective arrays using phase-conjugation techniques. The arrays presented here are designed for wireless communications in microwave bands and have other features in addition to self-phasing aspects such that they can be applied to practical communication systems. The reliance on purely analog circuitry offers system simplicity and high-speed response. The self-beam-steering feature potentially offers the improvement of communication link gain between an interrogator and a retrodirective array, reducing the burden on transmitting and receiving amplifiers. By implementing a receiving function, it has been demonstrated that retrodirective arrays can also be used in bidirectional communications in either a full or semiduplex manner, initiating a new class of transceiver architecture.

This paper provide a review of the active integrated antenna (AIA) technologies. After a brief introduction on the definition and some historical remarks, the paper concentrates on the research effort on the past decades or so. The AlAs are reviewed in its various functions. First, an oscillator-type AIA is presented, followed by very interesting aspects of coupled oscillator arrays for phase control. Use of an AIA concept for efficient RF front ends is described with examples on high-power amplifier AlAs. Next, a phase-conjugation-based retrodirective array is reviewed. Finally, AIA systems for receiving, transmitting, and duplexing are reviewed.

A two-dimensional finite volume time domain (FVTD) method using a triangular grid is applied to the analysis of electromagnetic wave propagation in a semiconductor. Maxwell's equations form the basis of all electromagnetic phenomena in semiconductors and the drift-diffusion model is employed to simulate charge transport phenomena in the semiconductor. The FVTD technique is employed to solve Maxwell's equations on an irregular grid and the finite box method is implemented on the same grid to solve the drift-diffusion model for carrier concentration. The locations of unknowns have been chosen to allow linking coupled Maxwell's equations and transport equations in a seamless way. To achieve suitable accuracy and computational efficiency, using irregular grid topology allows a finer mesh in doped region and at junction, and a coarser mesh in substrate and insulting regions. The proposed scheme has been implemented and verified by characterizing electromagnetic wave propagation at microwave frequency in a semiconductor slab with arbitrary doping profile. Copyright © 2002 John Wiley & Sons, Ltd.

A novel high-performance planar diplexer is developed based on the substrate integrated waveguide (SIW) with complementary split-ring resonators (CSRRs) etched on the waveguide surface. The proposed diplexer is operated below the characteristic cutoff frequency of the waveguide. The filtering response of the SIW-CSRR combined structure is investigated first. The diplexer is then implemented based on two cascaded two-pole bandpass filters. Equivalent circuit, simulated results and experimental verification are all provided. This diplexer shows advantages in terms of the compact size, low loss, high isolation, easy fabrication and integration with other circuits.

Manipulating and tailoring the electromagnetic wave properties of artificial negative index material, known as Metamaterials or left-handed (LH) material foresee inspiring relevance in modern radio communication systems. In particular, this paper addresses the application of left-handed material for building high performance tunable VCO (3.9–4.2 GHz) for the applications in portable and test & measurement equipments. The reported measured phase noise @ 1MHz offset is − 151dBc/Hz @ 1MHz offset from carrier with DC operating condition of 5V and 40mA, delivering output power more than 3dBm over the operating frequency band.

This paper focuses on phase noise measurement techniques and comments about the dangers of using cross-correlation techniques for measuring Phase noise below kT. This discussion is important for research, demonstrated on 1GHz VCSO, and validated using different measurement equipments.

Several types of multiplexers based on isolation circuits have been introduced and investigated. Combining method of two filtering circuits (CMTC) is one way to make multiplexers based on isolation circuits. This method fits well for designing contiguous channel triplexers. A triplexer based on CMTC consists of a conventional transmission line (TL) connected to a diplexer and a composite right/left-handed (CRLH) TL connected to a filter. The triplexer based on CMTC has two significant advantages. One is that it is not necessary to modify the design of a stand-alone filter and diplexer and there is freedom in the choice of filtering circuits. In addition, a designer does not need to perform three-dimensional full-wave optimization, because of a simple and straightforward design concept. In this paper, a triplexer prototype having 1, 1.125, and 1.25 GHz center frequencies, is designed and fabricated. The measured results show good agreement with the simulation results. © Cambridge University Press and the European Microwave Association 2014.

A scalable lumped-element equivalent circuit of a prematched, multifinger FET cell is proposed. The model is derived using a global modeling approach that exploits both circuit and full-wave analysis, accounting for phase delay along gate and drain manifolds. The availability of such a model is useful to perform fast performance analysis and optimization of the prematching network. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 174–178, 2002.

With the increase in speed and memory storage in modern computer systems, the finite-difference time-domain (FDTD) method for the solution of electromagnetic problems is rapidly becoming an attractive choice due to its programming simplicity and flexibility in the analysis of a wide range of structures. However, this technique has the drawback of high computer memory requirements and computational power, when analyzing large geometries. In this paper, a modified version of the FDTD method with increased memory efficiency is presented and applied to the calculation of the resonant frequencies of a dielectric resonator coupled to a microstrip line. In this novel approach, the divergence relationship, which spatially links the three electric-field and three magnetic-field components, is used to eliminate one component each of E and H. This leads to a more memory-efficient formulation, where only four field components are stored in the whole domain, with a direct memory reduction of 33% in the storage of the fields.

This paper presents a C-band push-pull power amplifier integrated with a modified uniplanar quasi-Yagi antenna. In this circuit, corrugation is added to the truncated ground plane of the antenna so that it can be used for both out-of-phase power combining and second harmonic tuning. By using the active integrated antenna concept, this novel circuit eliminates the usage of an ordinary 180/spl deg/ hybrid at the power-amplifier output stage, therefore eliminating the losses associated with the hybrid, resulting in a compact and high-efficiency power-amplifier design with intrinsic second harmonic suppression. At an operating frequency of 4.15 GHz, a maximum measured power-added efficiency (PAE) of 60.9% at an output power of 28.2 dBm has been achieved. The measured PAE is above 50% over a 260-MHz bandwidth. Additionally, the second harmonic radiation is found to be 30 dB below the fundamental in both E- and H-planes. When the circuit is subjected to a two-tone test, the measured third-order intercept point is 37 dBm, about 10 dB above the P/sub 1 dB/ point.

In this paper, the first gallium nitride (GaN) based high electron mobility transistor (HEMT) power amplifier design using an artificial neural network (ANN) modeling technique is presented. The ANN technique was used to model the small signal behavior of a device with a gate periphery of 1 mm and a gate length of 1 /spl mu/m over the broad frequency range from 1 GHz to 26 GHz with multiple bias points, based on fitting calculated S-parameters to measured S-parameters. A single stage amplifier constructed using these parameters showed a gain of about 7 dB and an output power of 1.2 W at 8 GHz when biased at V/sub ds/ = 20 V and I/sub ds/ 220 mA in class AB mode. The good agreement between measured and simulated results was shown in both S-parameter modeling and in amplifier design.

A novel technique, called the envelope-finite element (EVFE) method, is proposed as a more efficient full-wave time-domain modeling scheme of electromagnetic waves. The EVFE method simulates the signal envelope rather than the original signal waveform by de-embedding the signal carrier from the time-domain wave equation. The de-embedded equation is then solved in the time domain using finite-element methods based on Newmark-Beta time stepping. Compared to traditional time-domain simulation techniques such as finite difference time-domain or finite element time-domain methods, only the signal envelope needs to be sampled in EVFE simulation. This method can reduce computation time when signal envelope/carrier ratios are very small. The purpose of this paper is to introduce this new concept, by presenting the two-dimensional EVFE formulations, stability conditions, and some supporting numerical examples.

A new defected ground structure (DGS) for the microstrip line is proposed in this paper. The proposed DGS unit structure can provide the bandgap characteristic in some frequency bands with only one or more unit lattices. The equivalent circuit for the proposed defected ground unit structure is derived by means of three-dimensional field analysis methods. The equivalent-circuit parameters are extracted by using a simple circuit analysis method. By employing the extracted parameters and circuit analysis theory, the bandgap effect for the provided defected ground unit structure can be explained. By using the derived and extracted equivalent circuit and parameters, the low-pass filters are designed and implemented. The experimental results show excellent agreement with theoretical results and the validity of the modeling method for the proposed defected ground unit structure.