# Parallel Plate Capacitor using HFSS

1. ## Parallel Plate Capacitor using HFSS

Hello, Greetings to all.

I am new to hfss and is not familiar with the terminology as well. When I was looking for help, I came across an earlier thread in which they have assigned lumped port. The plates were in X-Y plane and the port was in Y-Z plane.

Can anyone please help me in understanding why the port is given in this direction? I may be having this doubt because I have no idea of why we are using 'lumped port' instead of wave port.

Kindly help me by giving the details.

With regards,
G_V

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2. ## Re: Parallel Plate Capacitor using HFSS

Welcome G_V,

In order to excite a TEM guided-wave mode, the port needs to contact both plates; this is why in your case it must be in either y-z or x-y. A lumped port is used for internal excitation, whereas a wave port excites modes from outside the simulation domain.

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3. ## Re: Parallel Plate Capacitor using HFSS

I still have doubts regarding selecting the port direction w.r.t different modes. Can you explain in detail or provide me with some study material regarding the same?

As you have mentioned above, does it mean that in TEM mode both the ports should be perpendicular to the plates and in contact with both? And using lumped port or wave port will make no differences?

Kindly help me with a detailed explanation.

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4. ## Re: Parallel Plate Capacitor using HFSS

Hi G_V,

There might be some confusion here. How and why are you trying to excite the capacitor? Why would you want different modes inside of it?

5. ## Re: Parallel Plate Capacitor using HFSS

Hi sir,

I actually want both the capacitor designing and parallel plate waveguide as well. Now, for capacitors should I give a voltage excitation or is lumped port enough? And when I am considering a parallel plate waveguide, how should I assign the ports for different modes?

When I am designing the capacitor, I am focusing more on the magnitude of the electric field.

Kindly explain me both.

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6. ## Re: Parallel Plate Capacitor using HFSS

Hi G_V,

The DC static fields inside the capacitor should be similar to those of the transverse cross-section of the PPW mode. A lumped/wave port should excite both, but these also are a 50 Ohm impedance, so your device won't be quite a capacitor. If you need it to function as a capacitor, you need to integrate it with some sort of circuit.

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