Numerical modeling of a nonuniform grating with FDTD

Abstract

of Higdon's fourth-order ABC, this width is five cells. As the size of the domain increases, the increased memory overhead shrinks in proportion to the size of the domain, making this procedure cost effective for large problems. A demonstration of the increased memory overhead when a five-cell-wide double-precision layer is used over that of the single-preci-Ž . sion simulation is shown in Figure 4 for 2D N = N and 3D Ž .Because of the limited scope of this Letter, results were presented only for Higdon's fourth-order ABC. This method was also found to be equally effective in stabilizing Liao's second-, third-, and fourth-order ABCs. IV. SUMMARYIn this Letter, a method is presented to stabilize FDTD solutions when using higher-order ABCs, while simultaneously maintaining accuracy over a wide range of frequencies.The method combines the use of damping factors in the ABC construction and double-precision arithmetic over only a portion of the computational domain. The effectiveness of the method was demonstrated for Higdon's fourth-order ABC. ABSTRACT: The need for a numerical analysis of a nonuniformgrating arises from antenna testing facilities. A hologram type of compact ( ) antenna test range CATR is a recently proposed method for antenna testing at millimeter wa¨elengths. Simulations of the quiet-zone field are done with a two-dimensional finite-difference᎐time domain method ( ) FDTD , combined with an exact near-field aperture integration method [ ( ) ] physical optics PO . ABSTRACT: MMIC microstrip single-gate cold mixers and dual-gate mixers ha¨e been de¨eloped, fabricated, and measured in V band. They ha¨e been processed on 0.15-or 0.25-m-gate AlGaAs r InGaAs r GaAs pseudomorphic HFET technology. The de¨ices are formed from an exhausti¨e methodology based on complex characterizations, specific nonlinear modeling and re¨erse engineering. A comparison for each MMIC is described from the chip process, from the same technology, under the same specifications.

Performance analysis of a submillimeter wave hologram CATR

“…When only one cut of the hologram is analyzed, an assumption, that the geometry does not change in the y-direction, has to be made. This kind of simplified structure can be simulated with a two-dimensional FDTD [2,3].…”

“…The transmission of the hologram depends on the polarization of the incoming field and the widths of the slots [2,3].…”

Reduction of numerical dispersion in FDTD method through artificial anisotropy

“…For this, let us introduce a parameter that defines the shape of a single FDTD cell 4Furthermore, we define a spatial resolution coefficient that relates the wavelength and cell dimensions (5) where is the wavelength in the vacuum (not in the numerical grid). Let us also define a Courant coefficient in accordance with (1) 6Using (4) and 6) (7and using (4) and (5)…”

“…Since one of the key advantages of the FDTD method is the possibility to perform wide-band simulations, it is clearly a disadvantage of the proposed correction method that it is optimal for only one frequency. However, due to other advantages, FDTD is sometimes used in single-frequency problems, e.g., [4].…”

A compact antenna test range based on a hologram

“…The slight asymmetry of the fields is a result of an offset of the slot location from the exact center of the hologram. The FDTD analysis is more thoroughly explained in [12].…”