My professor asked me to replace normal ground plane with infinite ground palne and compare between them for a patch antenna.
I don't know how to add a infinite ground plane in CST can somebody help me.
What is the difference between them and why do we need to use infinite ground plane.
A ground plane is like a mirror underneath the antenna. It generates an image of the antenna underneath it that also radiates and adds to the radiation pattern above the ground plane. The image can only radiate through a "window" the size of the ground plane. If the ground plane is not infinite then there will be directions where you can't see some of the reflection of the antenna in the ground plane, and the radiation here will be different to that if the ground plane was infinite. In addition to this, small ground planes can be resonant and have other effects on the radiation pattern. An infinite ground plane is big enough so none of these things happen. In CST I think you can't actually have an infinite ground plane, but you can make the ground reach the edges of the solution volume, and make this as large as possible, and put open boundary conditions where the ground hits the edges. I think you may need to "add space" so that CST doesn't know the ground plane stops here. CORRECTION CST help says do not use "add space" for an infinite ground plane!
Hello,
In CST, an infinite ground plane with an electric boundary, and a finite ground plane as an object can be modeled. With finite ground plane is looking like at the image of the antenna through an aperture the size of the ground plane. It is an infinite ground plane is an efficient method to model a large ground plane compared to a discretised, finite sized ground plane.
Paper is attached.
Thanks,
Buongiorno. Un ground plane con estensione infinita non può essere realizzato con un CAD come CST che vuole misure ben precise. Ciò che puoi fare è considerare un ground WxL (oppure pi*R^2, quello te lo vedi tu) in cui ogni dimensione, per esempio W risulta >> lambda. In generale quando lavori con dimensioni fisiche molto più grandi della lunghezza, si ha che l'estensione fisica è infinita, dal punto di vista proporzionale, poi ovviamente potrebbe esservi un rapporto lambda/W del tipo 1/10.000 o ancora meno. Mi sembra ci aver capito che lavori intorno ai 5 GHz, quindi lambda =3/50 [meters] con W che può essere per esempio 3000/50 ossia se lambda è 6cm, allora un patch quadrato può essere 6000 cm. Occhio ai valori di meshcells, non so quanta complessità tu possa avere. Una volta con un RFID di 915 MHz, ho introdotto un braccio di 8 cm e non ho avuto problemi.
Ps. Ricordati di aggiustare le proporzioni considerando che lambda0 è c/f e invece la lambda sul dielettrico è c/(f*sqrt(eps_r))
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