Three-dimensional simulations of frequency-phase measurements of arbitrary coupled-cavity RF circuits

Abstract

The frequency-phase characteristics of a coupled-cavity traveling-wave tube circuit have been calculated using the three-dimensional electromagnetic simulation code ARGUS. It is possible to determine the characteristics of the passbands by analysis of only half a cavity in three separate runs using different boundary conditions. Results show cavity mode frequencies calculated to within one-half percent of measured values. Additional capabilities desirable in a general cold testing code are described.

Dispersion retrieval from multi-level ultra-deep reactive-ion-etched microstructures for terahertz slow-wave circuits

“…The resonant frequencies are extracted from the return loss measurement and the HFSS Driven Modal Solution, noting the fact that the circuit of N cavities gives N resonances in the fundamental mode with an axial phase shift, k m p ¼ np=N þ 2p. 22 The dispersion obtained from the measurement is in good accordance with the simulation result. Here, a few dots near k m p ¼ 2p are missing, because they are out of range of the W-band (75 $ 110 GHz) vector network analyzer.…”

“…We also carried out the HFSS Eigenmode Solution 16 for the single unit cell structure, which provides an efficient way in analyzing periodic slow-wave circuits. Then, we found the lowest passband (mode 1), i.e., the cavity mode 22 and the next higher passband (mode 2), called the slot mode near the upper cutoff of the lowest passband. The cavity mode obtained from the HFSS Eigenmode Solution corresponds well to the measurement.…”

Study of An Extended Interaction Oscillator with A Rectangular Reentrance Coupled-cavity in Terahertz Region

“…The software CST is widely used to accurately simulate and compute the cold test characteristic. The method for calculating the RF phase shift per cavity is similar to that of Kantrowitz and Tammaru [14] where the frequency-phase dispersion is determined by obtaining resonant frequencies in truncated sections of circuit.…”

Optimization of Coaxial Couplers

“…The dielectric properties of the materials were defined to ensure an accurate computation of phase velocity of the wave and of the impedance of the total assembly. Perfect conducting boundary conditions were applied at the axial truncation points of the body tube [8]. Both input and output couplers were terminated with waveguide ports to simulate infinitely long waveguides at the boundaries of the calculation domain.…”