CST simulation Problem

[chinwi85]

Hello forum,
I am new with antenna and CST, sorry if there are some stupid questions;
In fact, I have a mini-project about simulating a pyramidal horn antenna, I don't know what exactly do, and what parameters should I play with to enhance the horn's gain, A great thanks for anyone can help me :
First, I have some questions:
- I don't know how to choose he range of frequencies for a given frequency,?
- Is the length of a waveguide affects (if too short or to long compared with the length of the horn), and how to choose it?
- I don't know about ports and modes, what influence occur with increasing/decreasing mode/port?
- what is the difference between the resonance frequency and the cut-off frequency, the latter should be within the range frequency?
- what is the mesh do exactly, why should I increase it's lines?

Second, I found this example:
<<Given: Gain = 20dB, Frequency =10GHz, (for example here what should the range of frequency be ???). The value of a (width) and b (high) of the waveguide part of the horn antenna are 6cm and 3cm respectively.
Calculated data:
Resonance Frequency = 5.59 GHz; A(horn's width) = 13.85 cm, B(horn's high) = 10.11 cm, L(horn's length) = 11.43 cm
The calculation of A, B and L, there is some parameter X to find first by iteration "I don't know how to calculate it :sad:", it is not detailed in the book "Antenna_Theory__Analysis_and_Design__3rd_Edition, Constantine_A._Balanis". if someone know how to calculate this parameter, please show some detail >>

Third, I putted the frequency range = [5,10], During the transient solver, The error show this "At least one propagating mode at port 1 is not considered in the time domain calculation! It might be better to increase the number of mode at port 1"

A picture of the model:

Please any help I will be very grateful;

 

[HPRF]

Hi,

To select your frequency range you need to select the circular icon with the white wave inside. Your choice of requency will depend on what you are looking for. If you are looking to analyse your horn at cutoff your frequency range should be around the cutoff value.

If you have many modes propogating to your port you need to set the number of modes to a higher values that lets the simulation look for these modes.

Your cut off value is determined by the waveguide that is feeding your horn antenna. See online for rectangular waveguide cutoff frequencies, there's plenty of site with help and some will even do the calculation for you.

As far as meshing goes, your structure does not have very fine detail in it so you shouldn't need a very fine mesh. Increasing 'lines per wavelength' increases the fineness of your mesh, i.e. how many hexahedral or tetrahedral mesh elements your structure is divided into. As a guide you should be working with a mesh size (no of elements) of between 500,000 and 2,000,000. Just adjust the lpw till you have something suitable.

 

[chinwi85]

That's help me, thank you very much:-D