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Questions related from Dimitrios V. Peponis
Consider a rectangular tapered waveguide, reminiscent of a horn antenna. Of course, the inclined PEC walls cannot accurately be represented by the Yee grid due to the staircase approximation....
26 April 2023 5,892 6 View
As far as I know, S Balance denotes the dissipated power from a structure's ports, and it is equal to unity for a lossless structure. I considered the following simplified structure: A smooth...
10 November 2022 7,035 0 View
In the literature and a lot of numerical codes, there are methods for decomposing the field in a waveguide in forward and backward components, such as here:...
13 January 2022 8,544 0 View
I simulated a smooth waveguide in CST Studio and calculated the S parameters. However, even if the waveguide is matched (using ports), there is a rippling behavior of those. What is the cause of...
21 May 2019 3,233 17 View
Lets assume a body rotating and m*du/dt=F, where u=(ux,uy,uz) and F=(Fx,Fy,Fz). If I would like to express the velocity in cylindrical coordinates, should I add an additional inertial force, such...
14 January 2019 6,573 3 View
Hello to all, Let's consider that a signal is sampled at every dt, creating a discrete signal of N samples. The frequency step in the fft should be 1/dt/N. But I expect that by increasing the...
17 October 2018 9,572 6 View
Usually in explicit time-integrator methods such as Boris Method, the maximum timestep is imposed by the Courant criterion due to the EM counterpart method (eg FDTD). Is there any empirical rule...
08 June 2018 7,036 3 View
Hello, The timestep can be calculated in cartesian coordinates using the formula dt = (1/c)/sqrt( 1/dx^2 + 1/dy^2 + 1/dz^2) But in cylindrical coordinates this gets more trickier. In lot of...
07 March 2018 6,998 3 View
Consider a waveguide (cylindrical or rectangular) which is terminated with a CPML layer in both ends, perpendicular on z-axis. The CPML layer is characterized by sz conductivity value, which...
07 October 2015 4,899 5 View
Assume to have a relativistic electron beam. First of all, can the beam treated as an electron plasma? If yes, how its plasma frequency can be calculated? This electron beam has specified...
02 September 2015 9,450 8 View
The question is fairly simple In the book "Gyrotrons: High-Power Microwave and Millimeter Wave Technology" from M. V. Kartikeyan, Edith Borie, Manfred Thumm, in page 107 a generalization of Busch...
22 May 2015 1,474 2 View
I am trying to benchmark a specific block of code and I found on the Internet a lot of ways, most of them using time.h and chrono.h libraries. But most of them are using system time and not actual...
13 October 2014 3,462 13 View
I'm trying to develop a 3D Cylindrical FDTD code with CPML boundary conditions regarding a simulation of a waveguide. So, CPML will be located at the far end of the waveguide along the z-axis...
20 May 2014 5,264 4 View
In a cylindrical FDTD code, with a closer look at descritized Maxwell equations, one can see that for different values for j indice (which indicates the angle) and for r=0 the values of the fields...
02 May 2014 4,938 1 View
Now I am using UPML for waveguide termination due to the simplicity and uniformity in the equations that describe it. But there is some cost, namely a larger number of operations and double the...
16 April 2014 6,131 4 View
The problem is the following one: Assuming a cylindrical cavity. Excitation used is the 2D distribution of electric field of TM mode (E_rho and E_phi components only) driven by a sinusoidal...
28 March 2014 5,442 22 View
I'm trying to figure out what library is the most accurate to date. I use in my codes GSL (GNU Scientific Library) which the most complete I found so far. Do you prefer something else, especially...
13 March 2014 4,377 6 View
I would like to simulate waveguides but because I "set" the stimulus at a specific transverse plane, the same plane acts as a reflection area. So, I would like to avoid this and use some kind of...
14 February 2013 9,471 1 View
First of all I've managed to build from scratch a 3D FDTD code for modelling waves travelling in cylindrical waveguides. The problem comes when I have to calculate nr, nf and nz where ni; i=r,f,z...
30 January 2013 9,569 2 View
A.Taflove's book "Computational Electrodynamics" explains well about dispersion in numerical schemes. But how can numerical wavenumber be actually be calculated, when only spatial steps and...
14 December 2012 7,812 5 View
How can anyone measure reflection coefficient from the PML region, using FDTD, in a hollow (εr=1) rectangular wave guide, knowing only the fields for every time step inside the wave guide, while...
13 November 2012 9,048 3 View
Including changing the wavelength to the smallest one and the appropiate space steps. Someone can use cells per wavelength using the smallest available wavelength, but when calculating timestep...
04 November 2012 9,503 7 View
