I used the waveguide port to excite the momopole antenna and get appropriate results and now i want to alter the type of port to discrete port but I got different results with discrete the port.
Any one have experienc to help?
I am not familiar with CST, I work in HFSS. In HFSS if the port is inside radiation box instead of waveport, a lumped port I used
What sort of feed did you simulate? A coaxial feed from under an infinite ground plane?
Firstly, I used WG port without SMA to feed coplanar antenna and I got S11 result that very close to the paper I am regenerating its results, then also I tried with SMA but the result is not as close as the first one. Whereas using DP gives alittle different result for this co-planner antenna.
Thanks for all replyers.
Your answer does not give enough information about the shape or impedance of the antenna at the feed point for anyone to be able to give an explanation.
The explanation may be because you made a mistake in one model, or because the fields around the feed and port excited by the waveguide mode and the discrete port are significanty different. From your description there is no way of telling this.
The impedance is 50 ohm as usual (exactly 50.92 ohm)and the shape is attached below.
The problem is for coplanar antenna using direct WaveGuide port has different result than Discrete port.
generally in some antenna structures, the difference is a little shift but for this it is not aceptable.
It looks as if you are applying the coaxial waveguide port directly to the simulated sma connector. In this situation it should work just fine. I expect the port mode displayed in the 3D results shows the correct fields and the table it shows on the screen at the same time will give the correct impedance and wavenumber.
Where did you apply the discrete port? It will not usually be a good match to a coaxial cable if it is along a radius because the fields around that discrete port are not in the same direction or place as all the coaxial fields, so there need to be evanescent modes to make up the difference, which are equivalent to inductance or capacitance at the port.
I put the Dicrete Port instead of WG port across the radius of coaxial. So how it can be conected instead? or no way to excite such structures with DP?
Thanks
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