Capacitance Calculation

  • Thread starter z3phyr
  • Start date
Hi there
I've encounted a problem in which I'm required to calculate the total capacitance between the end of a cylindrial rod and an infinite ground plane.

I've attached a schematic drawing here. The gap between the rod if far smaller than the diameter.

http://picasaweb.google.com/lh/photo/igUbKtbtX7AiyLX5tsQFQg?feat=directlink [Broken]

The part I cant figure out is the fringing capacitance from the sidewalls to the ground plane. I wonder if anybody has seem this problem before or know of any analytical/semi-analytical formula for estimating the fringing capacitance? I've done some numerical simulation with Ansoft Maxwell and I can definitely see a fringing field contribution that can not be neglected.

Greatly appreciated!
 

Attachments

Last edited by a moderator:

berkeman

Mentor
55,310
5,501
Hi there
I've encounted a problem in which I'm required to calculate the total capacitance between the end of a cylindrial rod and an infinite ground plane.

I've attached a schematic drawing here. The gap between the rod if far smaller than the diameter.

http://picasaweb.google.com/lh/photo/igUbKtbtX7AiyLX5tsQFQg?feat=directlink [Broken]

The part I cant figure out is the fringing capacitance from the sidewalls to the ground plane. I wonder if anybody has seem this problem before or know of any analytical/semi-analytical formula for estimating the fringing capacitance? I've done some numerical simulation with Ansoft Maxwell and I can definitely see a fringing field contribution that can not be neglected.

Greatly appreciated!
Welcome to the PF. It would seem that simulation would be your best bet. What is the application? What accuracy do you need?
 
Last edited by a moderator:
Hi Berkeman
Thanks for the reply. This is for the design of a combline/evanescent mode waveguide filter. Basically I'm trying to calculate the gap between the cylindrical post and the ground plane. It would be nice to have some formula for easy calculation and I'm almost certain that somebody, at sometime, must have tackled this problem. I just can't seem to find it in the literature...

Welcome to the PF. It would seem that simulation would be your best bet. What is the application? What accuracy do you need?
 

berkeman

Mentor
55,310
5,501
Cool problem. Is there a reason that the simulation route won't work for you?
 
No, simulation will work fine. It just the professor thinks it cool to use equations instead of simulations when presenting the work...

Cool problem. Is there a reason that the simulation route won't work for you?
 

Related Threads for: Capacitance Calculation

Replies
2
Views
479
Replies
12
Views
956
Replies
13
Views
2K
Replies
10
Views
793

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads

Top