摘要:

AbstractOptical tuning experiments were performed on an Al0.25Ga0.75As/GaAs HBT oscillator operating at 6 GHz. The HBT was fabricated with a transparent emitter ohmic contact made of indium‐tin‐oxide (ITO) to allow light input through the top of the device. Under direct illumination of the base and base‐collector depletion regions, optical tuning was observed with an increase in oscillation frequency of up to 25 MHz. The observed increase in frequency is attributed to a shift in resonance due to a decrease in the base‐emitter junction capacitance of the HBT under optical illumination. This effect is verified using detailed device and circuit modeling techniques. © 1995 John Wiley&S

ISSN:0895-2477    

DOI:10.1002/mop.4650090402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe perfectly matched layer (PML) concept, introduced by Berenger with the aim of synthesizing an absorbing boundary condition (ABC) for the finite‐difference‐time domain (FDTD) method, is modified and extended to finite‐element frequency‐domain (FEFD) applications. The governing equations that characterize this approach do not require the splitting of the field components of interest, nor do they involve negative conductivity parameters. The PML‐type medium is employed together with analytic and numerical ABCs as its termination to obtain an improved boundary condition for the FEFD method at a limited increase in computational cost. © 1995 John Wiley

ISSN:0895-2477    

DOI:10.1002/mop.4650090403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe full‐wave electromagnetic (EM) spectral‐domain approach so far applied to predominantly planar (2.5D) passive MIC / MMIC structures has been extended to the rigorous EM treatment of active devices like MESFETs/HEMTs incorporating the full metallization geometry. The presented approach is verified with a 1 × 300‐μm GaAs MESFET application example. © 1995 John Wiley&S

ISSN:0895-2477    

DOI:10.1002/mop.4650090404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA multiresolution wavelet concept is applied to efficiently represent the electrodynamic Green's function. In the joint spectral‐spatial representation, the multiscale feature of the spectral‐domain Green's function is clearly revealed. Due to this multiscale feature in the spectral domain, a wavelet application in the spectral domain (KDWT) is more appropriate in representing the Green's function than the wavelet transform applied in the space domain (SDWT). We present a multiresolution implementation of the KDWT and show that the KDWT representation results in a sparser moment impedance matrix than the SDWT representation. © 1995 John Wiley&Sons,

ISSN:0895-2477    

DOI:10.1002/mop.4650090405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA technique for the design of a two‐layered wave absorber for cylindrical objects using an expanded polystyrene mixed carbon coating is presented. The concentrations of the mixed carbon in the two absorbing layers and their thicknesses are determined from the design specifications. Design charts for the wave absorber for TE and TM polarizations are calculated, and their wideband absorbing characteristics are presented. © 1995 John Wiley&Sons, I

ISSN:0895-2477    

DOI:10.1002/mop.4650090406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of biasing and harmonic loading on GaAs MESFET tripler performance are studied. The Tajima large‐signal nonlinear model and the harmonic balance approach are used for this purpose. The output power, gain, and efficiency of a 5 ∼ 15‐GHz tripler, as functions of the fundamental and second harmonic load impedances, as well as the gate‐bias voltages, are investigated. Design guidelines for MESFET triplers are deduced. It is recommended, for any biasing, that the fundamental frequency load impedance be an inductive reactance away from the open‐circuit region, and that the second harmonic termination be in the short‐circuit region. © 1995 John Wil

ISSN:0895-2477    

DOI:10.1002/mop.4650090407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAn efficient method to solve the scattering by a cluster of randomly located discrete scatterers is described. The scatterers can have an arbitrary shape, and only their T matrices need be known. An iterative method is suggested to solve this problem. To expedite the matrix‐vector multiply, we first aggregate the random scattering centers of the scatterers into centers that reside on a regular array. Then, the FFT method is used to perform the matrix‐vector multiply in O(N log N) operations. This method can solve a problem with a large number of unknowns, involving thousands of discrete scatterers, on a workstation. © 1995 John Wiley&Sons,

ISSN:0895-2477    

DOI:10.1002/mop.4650090408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractActive antenna elements consisting of FET oscillators integrated with notch antennas have been used to create a 3 × 3 quasioptical power combining array. The array has a good power combining efficiency and a well‐defined main beam. The design of the FET active notch antenna element and the performance of the 3 × 3 array are discussed. © 1995 John Wiley&Sons,

ISSN:0895-2477    

DOI:10.1002/mop.4650090409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA dielectric lens structure, the effective refractive index of which varies with its radius, is studied experimentally at millimeter‐wave frequencies. The experimental results demonstrate that such a lens is suitable as a wideband compact power splitter for integrated optical circuits. © 1995 John Wiley&Sons, I

ISSN:0895-2477    

DOI:10.1002/mop.4650090410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractPulse‐position modulation (PPM) schemes are usually used in optical communication systems to improve the receiver sensitivity. Recently, multi‐PPM (MPPM) signaling [1] has been presented as a very powerful alternative to the PPM format, for laser direct detection systems. With similar information efficiency, it achieved a significant performance improvement at higher transmission rates, and had less bandwidth expansion, and better peak‐to‐average power ratios, with respect to the PPM model. In this article we investigate extending the MPPM signaling to coherent optical communication systems. © 1995 John Wiley&S

ISSN:0895-2477    

DOI:10.1002/mop.4650090411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY