Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1999"
TL;DR: In this paper, it was shown that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu/sub eff/, which can be tuned to values not accessible in naturally occurring materials.
Abstract: We show that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu//sub eff/, which can be tuned to values not accessible in naturally occurring materials, including large imaginary components of /spl mu//sub eff/. The microstructure is on a scale much less than the wavelength of radiation, is not resolved by incident microwaves, and uses a very low density of metal so that structures can be extremely lightweight. Most of the structures are resonant due to internal capacitance and inductance, and resonant enhancement combined with compression of electrical energy into a very small volume greatly enhances the energy density at critical locations in the structure, easily by factors of a million and possibly by much more. Weakly nonlinear materials placed at these critical locations will show greatly enhanced effects raising the possibility of manufacturing active structures whose properties can be switched at will between many states.
8,135 citations
TL;DR: In this paper, a new type of metallic structure has been developed that is characterized by having high surface impedance, which is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements and distributed in a two-dimensional lattice.
Abstract: A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.
4,264 citations
TL;DR: In this article, a new finite-difference time-domain (FDTD) algorithm is proposed in order to eliminate the Courant-Friedrich-Levy (CFL) condition restraint.
Abstract: In this paper, a new finite-difference time-domain (FDTD) algorithm is proposed in order to eliminate the Courant-Friedrich-Levy (CFL) condition restraint. The new algorithm is based on an alternating-direction implicit method. It is shown that the new algorithm is quite stable both analytically and numerically even when the CFL condition is not satisfied. Therefore, if the minimum cell size in the computational domain is required to be much smaller than the wavelength, this new algorithm is more efficient than conventional FDTD schemes in terms of computer resources such as central-processing-unit time. Numerical formulations are presented and simulation results are compared to those using the conventional FDTD method.
926 citations
TL;DR: In this article, the photonic bandgap (PBG) structure for microwave integrated circuits is presented, which is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches.
Abstract: This paper presents a novel photonic bandgap (PBG) structure for microwave integrated circuits. This new PBG structure is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches. Experimental results of a microstrip on a substrate with the PEG ground plane displays a broad stopband, as predicted by finite-difference time-domain simulations. Due to the slow-wave effect generated by this unique structure, the period of the PBG lattice is only 0.1/spl lambda//sub 0/ at the cutoff frequency, resulting in the most compact PEG lattice ever achieved. In the passband, the measured slow-wave factor (/spl beta//k/sub 0/) is 1.2-2.4 times higher and insertion loss is at the same level compared to a conventional 50-/spl Omega/ line. This uniplanar compact PBG (UC-PBG) structure can be built using standard planar fabrication techniques without any modification. Several application examples have also been demonstrated, including a nonleaky conductor-backed coplanar waveguide and a compact spurious-free bandpass filter. This UC-PBG structure should find wide applications for high-performance and compact circuit components in microwave and millimeter-wave integrated circuits.
831 citations
TL;DR: In this article, a simple recursion technique is described for the generation of the polynomials for even or odd-degree Chebyshev filtering functions with symmetrically or asymmetrically prescribed transmission zeros and/or group delay equalization zero pairs.
Abstract: Methods are presented for the generation of the transfer polynomials, and then the direct synthesis of the corresponding canonical network coupling matrices for Chebyshev (i.e., prescribed-equiripple) filtering functions of the most general kind. A simple recursion technique is described for the generation of the polynomials for even- or odd-degree Chebyshev filtering functions with symmetrically or asymmetrically prescribed transmission zeros and/or group delay equalization zero pairs. The method for the synthesis of the coupling matrix for the corresponding single- or double-terminated network is then given. Finally, a novel direct technique, not involving optimization, for reconfiguring the matrix into a practical form suitable for realization with microwave resonator technology is introduced. These universal methods will be useful for the design of efficient high-performance microwave filters in a wide variety of technologies for application in space and terrestrial communication systems.
804 citations
TL;DR: In this paper, the surface wave dispersion diagram of the UC-PBG substrate has been numerically computed for two different substrate thickness (25 and 50 mil) and found to have a complete stopband in the frequency range of 10.9-13.5 and 11.4-12.8 GHz, respectively.
Abstract: The recently developed uniplanar compact photonic bandgap (UC-PBG) substrate is successfully used to reduce surface-wave losses for an aperture-coupled fed patch antenna on a thick high dielectric-constant substrate. The surface-wave dispersion diagram of the UC-PBG substrate has been numerically computed for two different substrate thickness (25 and 50 mil) and found to have a complete stopband in the frequency range of 10.9-13.5 and 11.4-12.8 GHz, respectively. The thicker substrate is then used to enhance broadside gain of a patch antenna working in the stopband at 12 GHz. Computed results and measured data show that, due to effective surface-wave suppression, the antenna mounted on the UC-PBG substrate has over 3-dB higher gain in the broadside direction than the same antenna etched on a grounded dielectric slab with same thickness and dielectric constant. Cross-polarization level remains 13 dB down the co-polar component level for both E- and H-planes.
493 citations
TL;DR: In this paper, a photonic-bandgap (PBG) substrate for patch antennas is proposed, which minimizes the surface-wave effects and shows significantly reduced levels of surface modes compared to conventional patch antennas, thus improving the gain and far field radiation pattern.
Abstract: The microstrip patch antenna is a low-profile robust planar structure. A wide range of radiation patterns can be achieved with this type of antenna and, due to the ease of manufacture, is inexpensive compared with other types of antennas. However, patch-antenna designs have some limitations such as restricted bandwidth of operation, low gain, and a potential decrease in radiation efficiency due to surface-wave losses. In this paper, a photonic-bandgap (PBG) substrate for patch antennas is proposed, which minimizes the surface-wave effects. In order to verify the performance of this kind of substrate, a configuration with a thick substrate is analyzed. The PBG patch antenna shows significantly reduced levels of surface modes compared to conventional patch antennas, thus improving the gain and far-field radiation pattern.
444 citations
TL;DR: In this article, a boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors, and an envelope detector circuit with a fast feedback loop regulator is discussed.
Abstract: Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. This paper discusses improvements in system efficiency that are obtainable when a DC-DC converter is used to convert available battery voltage to an optimal supply voltage for the output RF amplifier. A boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors. Advantages of 10 MHz switching frequency and associated loss mechanisms are described. For modulation formats with a time-varying envelope, such as CDMA, the probability of power usage is described. Gains in power efficiency and battery lifetime are calculated. An envelope detector circuit with a fast feedback loop regulator is discussed. Effects of varying supply voltage with respect to distortion are examined along with methods to increase system linearity.
395 citations
TL;DR: In this article, a photonic bandgap (PBG) structure is proposed to realize a magnetic surface in the stopband and is used in the waveguide walls to provide magnetic boundary conditions.
Abstract: A novel waveguide using a photonic bandgap (PBG) structure is presented. The PBG structure is a two-dimensional square lattice with each cell consisting of metal pads and four connecting lines, which are etched on a conductor-backed Duroid substrate. This uniplanar compact PBG structure realizes a magnetic surface in the stopband and is used in the waveguide walls to provide magnetic boundary conditions. A relatively uniform field distribution along the cross section has been measured at frequencies from 9.4 to 10.4 GHz. Phase velocities close to the speed of light have also been observed in the stopband, indicating that TEM mode has been established. A recently developed quasi-Yagi antenna has been employed as a broad-band and efficient waveguide transition. Meanwhile, full-wave simulations using the finite-difference time-domain method provide accurate predictions for the characteristics of both the perfect magnetic conductor impedance surface and the waveguide structure. This novel waveguide structure should find a wide range of applications in different areas, including quasi-optical power combining and the electromagnetic compatibility testing.
383 citations
TL;DR: In this paper, a photonic bandgap (PBG) reflector was designed using a finite-difference time-domain (FDTD) code, and the FDTD computations provided the theoretical reflector's directivity.
Abstract: This paper introduces two new photonic bandgap (PBG) material applications for antennas, in which a photonic parabolic reflector is studied. It is composed of dielectric parabolic layers associated to obtain a PBG material. The frequency gap is used to reflect and focus the electromagnetic waves. This device has been designed using a finite-difference time-domain (FDTD) code. FDTD computations have provided the theoretical reflector's directivity. These results are in good agreement with measurements, and it appears that the PBG reflector presents the same directivity as a metallic parabola. A second application uses a defect PBG material mode associated with a metallic plate to increase the directivity of a patch antenna. We explain the design of such a device and propose experimental results to validate the theoretical analysis.
363 citations
TL;DR: In this article, two main trends in the progress of ultrawide-band/high-frequency photodetectors (PD's), improving the bandwidth-efficiency product and obtaining a high saturation current, are reviewed.
Abstract: The two main trends in the progress of ultrawide-band/high-frequency photodetectors (PD's), improving the bandwidth-efficiency product and obtaining a high saturation current, are reviewed. With respect to achieving large bandwidth-efficiency, the limiting factors and potentials of edge-coupled (waveguide, waveguide-fed, traveling-wave, periodic-traveling-wave), resonant-cavity, and refracting-facet photodiodes, as well as the avalanche photodiode are discussed. Regarding high-saturation current, the author estimated how much the space-charge effect limits the saturation current and two ways to reduce the space-charge effect are outlined. One way is to distribute the photocarriers along the edge-coupled PD's and the other is to increase the carrier velocity using a uni-traveling carrier structure. The waveguide-photodiode-based technologies that we have developed are also presented; namely the design and fabrication of a 100-GHz waveguide photodiode (WGPD), uni-traveling carrier WGPD, 60-GHz packaging, and a 20-GHz large-core WGPD for planar lightwave circuit integration. A 50-Gb/s receiver opto-electronic integrated circuit technology based on the WGPD is also presented.
TL;DR: In this article, the authors describe a strategy to characterize power and groundplane structures using a full cavity-mode frequency-domain resonator model, and introduce a novel technique to suppress modal impedances, minimizing both transfer and input impedances.
Abstract: In this paper, we describe a strategy to characterize power and ground-plane structures using a full cavity-mode frequency-domain resonator model. We develop insights into modal analysis and introduce a novel technique to suppress modal impedances, minimizing both transfer and input impedances. The influence of port locations on the Z matrix is evaluated.
TL;DR: In this paper, the authors proposed to use micro-scale vibrating resonators as integrated circuit-compatible tanks for use in the low phase-noise oscillators and highly selective filters of communications subsystems.
Abstract: With Q's in the tens to hundreds of thousands, micromachined vibrating resonators are proposed as integrated circuit-compatible tanks for use in the low phase-noise oscillators and highly selective filters of communications subsystems. To date, LF oscillators have been fully integrated using merged CMOS/microstructure technologies, and bandpass filters consisting of spring-coupled micromechanical resonators have been demonstrated in a frequency range from HF to VHF. In particular, two-resonator micromechanical bandpass filters have been demonstrated with frequencies up to 35 MHz, percent bandwidths on the order of 0.2%, and insertion losses less than 2 dB. Higher order three-resonator filters with frequencies near 455 kHz have also been achieved, with equally impressive insertion losses for 0.09% bandwidths, and with more than 64 dB of passband rejection. Additionally, free-beam single-pole resonators have recently been realized with frequencies up to 92 MHz and Q's around 8000. Evidence suggests that the ultimate frequency range of this high-Q tank technology depends upon material limitations, as well as design constraints, in particular, to the degree of electromechanical coupling achievable in microscale resonators.
TL;DR: In this paper, the specific absorption rate (SAR) in the human head was determined using the finite-difference time-domain (FDTD) method, while a bioheat equation was numerically solved also using the FDTD method.
Abstract: Temperature rises in the human head for portable telephones were computed with an anatomically based head model at 900 MHz and 1.5 GHz. The specific absorption rate (SAR) in the human head was determined using the finite-difference time-domain (FDTD) method, while a bioheat equation was numerically solved also using the FDTD method. The portable telephone was modeled by a quarter-wavelength monopole antenna on a dielectric covered metal box. The source geometries considered were the telephone barely touching the ear and the telephone pressing the ear, both having a vertical alignment at the side of the head. The antenna output power was set to be consistent with the portable telephones of today: 0.6 W at 900 MHz and 0.27 W at 1.5 GHz. Computed results show that a phone time of 6-7 min yields a temperature rise of approximately 90% of the steady-state value. Application of the ANSZ/IEEE safety guidelines restricting the 1-g-averaged spatial peak SAR to 1.6 W/kg results in the maximum temperature rise in the brain of 0.06/spl deg/C, and application of the ICNIRP/Japan safety guidelines restricting the 10-g-averaged spatial peak SAR to 2 W/kg results in the maximum temperature rise in the brain of 0.11/spl deg/C, both at 900 MHz and 1.5 GHz.
TL;DR: In this article, an analog-to-digital (A/D) conversion based on photonic time stretch is proposed, where the analog electrical signal is intensity modulated on a chirp optical waveform generated by dispersing an ultrashort pulse.
Abstract: We demonstrate a new concept for analog-to-digital (A/D) conversion based on photonic time stretch. The analog electrical signal is intensity modulated on a chirp optical waveform generated by dispersing an ultrashort pulse. The modulated chirped waveform is dispersed in an optical fiber, leading to the stretching of its envelope. We have derived analytical expressions for the stretch factor and the resolution of the system. An analog-to-digital converter (ADC) consisting of the photonic time-stretch preprocessor and a 1-Gsample/s electronic ADC is demonstrated. This technique is promising for A/D conversion of ultrafast signals and, hence, for realization of the digital receiver.
TL;DR: In this article, the authors describe the design and fabrication of distributed analog phase shifters, which consist of coplanar-waveguide (CPW) lines that are periodically loaded with varactor diodes.
Abstract: This paper describes the design and fabrication of distributed analog phase-shifter circuits. The phase shifters consist of coplanar-waveguide (CPW) lines that are periodically loaded with varactor diodes. The circuits are fabricated on GaAs using standard monolithic processing techniques. The phase velocity on these varactor diode-loaded CPW lines is a function of applied reverse bias, thus resulting in analog phase-shifting circuits. Optimally designed circuits exhibit 0/spl deg/-360/spl deg/ phase shift at 20 GHz with a maximum insertion loss (IL) of 4.2 dB. To the best of our knowledge, this is the lowest reported IL for a solid-state analog phase shifter operating at 20 GHz.
TL;DR: In this paper, a planar dual-mode filter is proposed for hybrid and monolithic microwave and millimeter-wave integrated-circuit design, which uses a pair of unequal crossed slots on a square patch resonator such that its radiation loss and structure size can be significantly reduced simultaneously.
Abstract: A class of new planar dual-mode filters are proposed and developed for hybrid and monolithic microwave and millimeter-wave integrated-circuit design. The novelty of the proposed structure is to use a pair of unequal crossed slots that are formed on a square patch resonator such that its radiation loss and structure size can be significantly reduced simultaneously. The physical background of the crossed slots on the patch resonator is explained. Our simulation results show that the proposed filter presents a number of attractive features for practical applications. It is found that the resonant frequency of a filter is reduced, e.g., by 36%, while its unloaded Q/sub 0/ is improved from 180 to 310 as the crossed slot length increases. The coupling characteristics of two degenerate modes backed by a resonator are studied with respect to unequal length of the crossed slots. A dual-mode filter is designed and fabricated with 1.6% bandwidth operating at 1.6 GHz to showcase our proposal. Measured results validate the design predictions well.
TL;DR: In this paper, the relationship between resonant frequencies, dimensions of the resonant structure, and permittivity of the sample under test is calculated with a radial mode-matching technique.
Abstract: Whispering-gallery modes are used for very accurate permittivity, dielectric loss, and temperature coefficient of permittivity measurements for both isotropic and uniaxially anisotropic dielectric materials. The relationship between resonant frequencies, dimensions of the resonant structure, and permittivity of the sample under test is calculated with a radial mode-matching technique. The relative accuracy of these computations is better then 10/sup -4/. The influence of conductor losses on dielectric loss tangent determination is treated for both whispering-gallery-mode and TE/sub 01/spl delta//-mode dielectric-resonator techniques. Two permittivity tensor components of sapphire and their temperature dependence were measured from 4.2 to 300 K. The total uncertainty in permittivity when use is made of whispering-gallery modes was estimated to be less than 0.05%. The uncertainty was limited principally by uncertainty in sample dimensions. Experimental and calculated resonant frequencies of several whispering-gallery modes differed by no more than 0.01%. The dielectric loss tangent of sapphire parallel and perpendicular to its anisotropy axis was calculated to be less than 10/sup -9/ at 4.2 K. The permittivity and dielectric loss tangent of a commercially available low-loss high-permittivity ceramic material has also been measured at S- and C-band frequencies using a large number of whispering-gallery modes.
TL;DR: In this paper, the authors presented modeling of microwave circuits using artificial neural networks (ANN's) based on space-mapping (SM) technology, which decrease the cost of training, improve generalization ability, and reduce the complexity of the ANN topology with respect to the classical neuromodeling approach.
Abstract: For the first time, we present modeling of microwave circuits using artificial neural networks (ANN's) based on space-mapping (SM) technology, SM-based neuromodels decrease the cost of training, improve generalization ability, and reduce the complexity of the ANN topology with respect to the classical neuromodeling approach. Five creative techniques are proposed to generate SM-based neuromodels. A frequency-sensitive neuromapping is applied to overcome the limitations of empirical models developed under quasi-static conditions, Huber optimization is used to train the ANN's. We contrast SM-based neuromodeling with the classical neuromodeling approach as well as with other state-of-the-art neuromodeling techniques. The SM-based neuromodeling techniques are illustrated by a microstrip bend and a high-temperature superconducting filter.
TL;DR: In this paper, a linearly chirped fiber grating and a laser array are used to provide full transfer-function reconfiguration and resonance tunability for radio frequency filters.
Abstract: We propose a novel kind of radio-frequency filters that are composed by a linearly chirped fiber grating and a laser array. These structures are capable of providing full transfer-function reconfiguration and resonance tunability. A thorough theoretical modeling and operation features are provided along with the experimental demonstration of the proposed features.
TL;DR: In this paper, a 2.5-THz Schottky diode mixer was developed and implemented as a monolithic membrane-diode (MOMED) structure.
Abstract: A novel GaAs monolithic membrane-diode (MOMED) structure has been developed and implemented as a 2.5-THz Schottky diode mixer. The mixer blends conventional machined metallic waveguide with micromachined monolithic GaAs circuitry to form, for the first time, a robust, easily fabricated, and assembled room-temperature planar diode receiver at frequencies above 2 THz. Measurements of receiver performance, in air, yield at T/sub receiver/ of 16500-K double sideband (DSB) at 8.4-GHz intermediate frequency (IF) using a 150-K commercial Miteq amplifier. The receiver conversion loss (diplexer through IF amplifier input) measures 16.9 dB in air, yielding a derived "front-end" noise temperature below 9000-K DSB at 2514 GHz. Using a CO/sub 2/-pumped methanol far-infrared laser as a local oscillator at 2522 GHz, injected via a Martin-Puplett diplexer, the required power is /spl ap/5 mW for optimum pumping and can be reduced to less than 3 mW with a 15% increase in receiver noise. Although demonstrated as a simple submillimeter-wave mixer, the all-GaAs membrane structure that has been developed is suited to a wide variety of low-loss high-frequency radio-frequency circuits.
TL;DR: In this article, three electrooptic-based terahertz imaging systems are described and discussed: the point scanning system, a two-dimensional charge-coupled device (CCD) system and a one-dimensional spatio-temporal chirped pulse imaging system.
Abstract: In this paper, we describe and discuss three electrooptic-based terahertz imaging systems: the point scanning system, a two-dimensional charge-coupled device (CCD) system and a one-dimensional spatio-temporal chirped pulse imaging system. A complete comparison between the scanning system and CCD systems is given. We emphasize the CCD systems that provide high acquisition speed by taking unique advantage of parallel measurement. Possible improvements are also discussed.
TL;DR: In this paper, the large-signal intermodulation distortion (IMD) sweet spots in microwave power amplifiers are studied and predicted using a new mathematical basis, and the variations in the IMD versus drive pattern with active bias point and the terminating matching networks are investigated.
Abstract: In this paper, large-signal intermodulation distortion (IMD) sweet spots in microwave power amplifiers are studied and predicted using a new mathematical basis. The variations in the IMD versus drive pattern with active bias point and the terminating matching networks are investigated. This nonlinear distortion model enabled the design of power amplifiers specially tailored to present a desired IMD versus drive-level pattern. For practical validation purposes, a MESFET case study and an illustrative application example are presented.
TL;DR: In this article, the basic principle of operation, design issues, limitations, recent developments and emerging research trends on widebandwidth lasers and modulators for radio-frequency photonic applications are reviewed.
Abstract: In this paper, the basic principle of operation, design issues, limitations, recent developments and emerging research trends on wide-bandwidth lasers and modulators for radio-frequency photonic applications are reviewed. The topics covered are wide-bandwidth lasers, lumped and traveling-wave electroabsorption modulators, traveling-wave LiNbO/sub 3/, GaAs, and polymer modulators.
TL;DR: In this paper, a statistical technique is presented for the characterization of spectral regrowth at the output of a nonlinear amplifier driven by a digitally modulated carrier in a digital radio system.
Abstract: A statistical technique is presented for the characterization of spectral regrowth at the output of a nonlinear amplifier driven by a digitally modulated carrier in a digital radio system. The technique yields an analytical expression for the autocorrelation function of the output signal as a function of the statistics of the quadrature input signal transformed by a behavioral model of the amplifier. The amplifier model, a baseband equivalent representation, is derived from a complex radio-frequency envelope model, which itself is developed from readily available measured or simulated amplitude modulation-amplitude modulation and amplitude modulation-phase modulation data. The technique is used in evaluating the spectral regrowth for a CDMA signal.
TL;DR: In this paper, a broadband spatial power-combining system implemented in a standard X-band waveguide environment is presented, using 24 off-the-shelf GaAs monolithic-microwave integrated-circuit (MMIC) power amplifiers integrated with tapered-slot antenna arrays.
Abstract: In this paper, we present new results in the development of a broad-band spatial power-combining system implemented in a standard X-band waveguide environment. Using 24 off-the-shelf GaAs monolithic-microwave integrated-circuit (MMIC) power amplifiers integrated with tapered-slot antenna arrays, the new combining circuit produced up to 126-W maximum power output with a gain variation of /spl plusmn/1.9 dB within the band of interest (8-11 GHz). This hybrid circuit combiner is transparent to the device technology, and also provides an excellent heat-sinking capacity, sustaining as much as 415 W of dc power consumed by the MMIC amplifiers. The modular architecture allows easy maintenance, variable output power level, and modular assembly. Results on graceful degradation are also presented, showing superb tolerance to device failure.
TL;DR: A comprehensive analysis of various techniques currently used for assessing microwave components' nonlinear distortion behavior is presented in this paper, where the output of a third-order system subject to a two- or three-tone input is given, and then used as the comparison reference for studying the response to a general multitone or random excitation.
Abstract: A comprehensive analysis of various techniques currently used for assessing microwave components' nonlinear distortion behavior is presented in this paper. The output of a third-order system subject to a two- or three-tone input is given, and then used as the comparison reference for studying the response to a general multitone or random excitation. Theoretical results thus obtained allowed the generalization of standard two-tone intermodulation (IMD) figures of merit, to multitone IMD ratio, multitone or noise adjacent channel power ratio, and noise power ratio (NPR). This approach proved that normal NPR tests produce optimistic results that can be as large as 7 dB when evaluating in-band co-channel power interference.
TL;DR: In this paper, a novel microstrip-to-waveguide transition utilizing a coplanar-strip Yagi-like antenna is presented, which achieves very broad bandwidth and relatively low insertion loss.
Abstract: A novel microstrip-to-waveguide transition utilizing a coplanar-strip Yagi-like antenna is presented. The compact and single-layered quasi-Yagi antenna fabricated on high dielectric-constant substrate has end-fire radiation patterns. This monolithic-microwave integrated-circuit (MMIC)-compatible antenna is inserted in the E-plane of the rectangular waveguide to launch the TE/sub 10/ dominant mode. With this new scheme of excitation, compact design and low-cost fabrication is achieved without requiring multilayered substrate or backshort hermetic sealing. This transition, in addition, achieves very broad bandwidth and relatively low insertion loss. The transition's broad-band characteristics are analyzed, and optimization guidelines for individual components of the transition are discussed in detail. A tolerance study proves that the transition is robust in mechanical alignment. The X-band transition with alumina substrate demonstrates 35% bandwidth with return loss better than -12- and -0.3-dB insertion loss at the center frequency. This transition should find wide applications due to its high compatibility with microwave-integrated-circuit/MMIC technology and very low fabrication cost.
TL;DR: In this article, the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter is presented, based on semiconductor lasers that are directly phase locked without the use of any other phase noise-reduction mechanisms.
Abstract: In this paper, we present the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter. The transmitter is based on semiconductor lasers that are directly phase locked without the use of any other phase noise-reduction mechanisms. In this transmitter, the lasers have a free-running summed linewidth of 6 MHz and the OPLL has a feedback bandwidth of 70 MHz. A state-of-the-art performance is obtained, with a total phase-error variance of 0.05 rad/sup 2/ (1-GHz bandwidth) and a carrier phase-error variance of 7/spl times/10/sup -4/ rad/sup 2/ in a 15-MHz bandwidth. Carriers are generated in the range of 7-14 GHz. The OPLL transmitter has been fully packaged for practical use in field trials. This is the first time this type of transmitter has been fabricated in a packaged state which is a significant advance on the route to practical application.
TL;DR: In this article, a model where the fringing fields are rigorously accounted for and the resonance condition is derived is presented, and a method for nondestructively measuring the complex permittivity of materials is examined.
Abstract: This paper presents a full-wave analysis of the split-cylinder resonator. We outline a model where the fringing fields are rigorously accounted for and the resonance condition is derived. Using this model, a method for nondestructively measuring the complex permittivity of materials is examined. Measurements of the complex permittivity for low-loss dielectric materials using the split-cylinder resonator agree well with measurements made in a cylindrical cavity. An uncertainty analysis for the complex permittivity is also provided.