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In this paper experimental measurement of a W-band gyrotron travelling wave amplifier (gyro-TWA) which is upgraded to operate at a high output power and wide frequency band will be presented. The gyro-TWA based on helically corrugated interaction region and cusp electron beam source can output a maximum power of ∼5 kW at its centre frequency of ∼94 GHz with an instantaneous frequency bandwidth of...
Two designs of fundamental mode rectangular to circular waveguide TE10 to TE11 mode converter are presented. The waveguide transitions are optimized for operation as an input coupler on a 372 GHz gyro-TWA for Dynamic Nuclear Polarization (DNP) enhancement of NMR imaging. A T-junction input coupler and a multiple hole directional coupler were optimized for operation between 360–384 GHz. The T-junction...
The design of two fundamental mode rectangular to circular waveguide mode converters are presented. The waveguide transitions are optimized for operation as an input coupler on a 372 GHz gyro-TWA for Dynamic Nuclear Polarization (DNP) enhancement of NMR imaging. A T-junction input coupler and a multiple hole directional coupler were optimized for operation between 360–384 GHz. The T-junction coupler...
Combing the advantages of high beam current density in a pseudospark-sourced electron beam and large beam cross section in a sheet electron beam, the design of a 0.2 THz extended interaction oscillator driven by a pseudospark-sourced sheet electron beam is presented in this paper. An interaction circuit with excellent design performance while at the same time being compatible with conventional manufacturing...
A hybrid tuning method for microwave filters with asymmetric phase shift effects is presented in this paper. This novel tuning technique is based on the combination of the modified Cauchy method and aggressive space mapping (ASM) technique. After remove the phase shift effect, Cauchy method is applied to determine the characteristic polynomials of the filter's response. Then the parameters (coupling...
ThThe combination of the large uniaxial magnetocrystalline anisotropy (7×107 erg/cm3) of L10 ordered FePt and the large Ms of FeCo is quite attractive for the practical application to high density magnetic recording media and for developing innovative permanent magnets [1,2]. Moreover, it is predicted by the first-principle calculations that the tetragonal distortion (c/a∼1.25) yields a large uniaxial...
A practical method for extracting the coupling matrix from measured or electromagnetic simulated S-parameters of narrow band cross-coupled filters with large losses is presented in this paper. The method can be applied to computer-aided tuning or computer-aided design of microwave filters to accelerate the filter design and physical implementation. The modified band-pass to low-pass transformation...
A lossy filter rational model extraction technique based on modified Cauchy method is presented in this paper. The conventional Cauchy method is only for lossless case, not suitable for lossy filter. The rational polynomials model is the prerequisite to synthesize the low-pass prototype (the evaluation of the coupling matrix) for computer-aided tuning. To this purpose, we modify the conventional Cauchy...
In this work, we investigated the failure behavior of a commercial chip size packaging (CSP) under coupling fields of electrical current and thermal cycles. The failure process was real-time monitored through the response resistance change. Under the coupling condition, the lifetime was much shorter than that in single thermal cycle condition. Instead of the void accumulation mechanism, the excessive...
Temperature-dependent femtosecond optical spectroscopy is used to track polaron dynamics in the spin and charge frustrated system LuFe2O4, revealing the influence of charge and spin ordering on polaron excitation, redressing, and coupling to on-site excitations.
We demonstrate a tapered dual-core fiber that splices to standard fiber at one end and butt couples to an uncoated InP ridge waveguide at the other, achieving a fiber-to-chip coupling loss of ~1.8 dB.
This paper propose the utilization of a photolithographic process to elevate the metal lines position that relative to the wafer plane, in order to take advantage from the signal propagation practically on-the-air, gained an almost ideal TEM mode of propagation in CPW structure. S-parameter and coupling degree of CPW with porous Si (PS), SOI and high resistivity silicon (HRS), SOI substrates are compared.
This paper describes the mutual consistency maintenance mechanism used in a prototype Data Traffic Management System (DTMS), which was designed and implemented to integrate several independent and stand-alone data systems owned by the U. S. Army, Corp of Engineers (CE). The major design constraints were that no modification to the data systems involved were allowed and that the update to each duplicate...
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