How to measure parasitic capacitance between rf cable and metal surface

In summary, the conversation discusses the issue of parasitic capacitance between a transmission line and a metallic surface, and how it can induce interference. The question also asks for ways to measure this interference and references on the allowable induced voltage. The conversation also touches on the use of baluns to reduce interference in unshielded transmission lines, specifically with regards to coaxial cables passing over metal surfaces.
  • #1
amr_sayed
2
0
dear all

can anyone tell me..
if i have a transmission line passed above a metalic surface, there will be a parasitic capacitance between the line and the surface. and it induces interference how can i measure it.
and if there is any refrenece about the allowable induce voltage interference for this capacitance.

thank you
 
Engineering news on Phys.org
  • #2
What kind of transmission line are you asking about? Are you asking about AC Mains high voltage power lines, or signal level coax, or balanced twin lead low-voltage cable (like TV antenna cable), or what?

And why would just passing above a metal surface induce interference? Is there some inherent noise present on the metal surface with respect to something else?
 
  • #3
The easiest way is to measure power factor. Good thing I can spell it.
 
  • #4
reply

it is an rf cable connected by antenna like TV antenna cable. the cable is passed above metal surface that may be charged like aircraft metallic surface
 
  • #5
amr_sayed said:
it is an rf cable connected by antenna like TV antenna cable. the cable is passed above metal surface that may be charged like aircraft metallic surface

If you have an unshielded balanced transmittion line, and you are worried about interference from a nearby source, consider using a balun at the antenna to match to coax. A coaxial transmission line is much less sensitive to noise sources.
 
  • #6
I'm thinking he's talking about coaxial cable; if it will get interference/coupling from having it pass over a metal roof or something.
 
  • #7
dlgoff said:
I'm thinking he's talking about coaxial cable; if it will get interference/coupling from having it pass over a metal roof or something.

It shouldn't, as long as a good balun is used at the antenna end (for balanced-to-unbalanced conversion), and as long as the receiving end is well shielded with a good coax shield termination.
 
  • #8
That was my thought. Wikipedia has a good page on http://en.wikipedia.org/wiki/Coaxial_cable" .
 
Last edited by a moderator:

What is parasitic capacitance?

Parasitic capacitance is the unintentional capacitance that exists between two conductors due to their proximity to each other. This can have a significant impact on the performance of electronic circuits, especially in high frequency applications.

Why is it important to measure parasitic capacitance between rf cable and metal surface?

Measuring parasitic capacitance between rf cable and metal surface is important because it allows us to accurately characterize and understand the behavior of electronic circuits. This information can then be used to improve the performance and reliability of these circuits.

What tools are needed to measure parasitic capacitance?

To measure parasitic capacitance, you will need a capacitance meter, an rf cable, and a metal surface. You may also need a signal generator and an oscilloscope to generate and measure the rf signals.

How do you measure parasitic capacitance between rf cable and metal surface?

To measure parasitic capacitance, you will need to connect one end of the rf cable to the capacitance meter and the other end to the metal surface. Then, using the signal generator, apply a known frequency to the rf cable. The capacitance meter will then measure the parasitic capacitance between the rf cable and the metal surface.

What factors can affect the accuracy of the measurement?

The accuracy of the measurement can be affected by several factors, including the quality of the rf cable and metal surface, the frequency of the signal used, and the distance between the two conductors. It is important to ensure that these factors are consistent and controlled in order to obtain accurate measurements.

Similar threads

Capacitance (intended and parasitic)
    • Electrical Engineering
Replies
17
Views
2K
Basics of RF coil development for MRI
    • Electrical Engineering
Replies
11
Views
2K
Question about Parasitic capacitances and physical grounds
    • Electrical Engineering
Replies
5
Views
3K
Frequency selective surface radome
    • Electrical Engineering
Replies
7
Views
1K
Building RF Noise Generator Circuit w/ LM324D SMD Op Amp
    • Electrical Engineering
Replies
12
Views
2K
Measuring ripple reduction in LTSpice
    • Electrical Engineering
Replies
22
Views
5K
Surface oxidation of aluminum alloy and electrical continuity
    • Electrical Engineering
Replies
11
Views
318
RF cavities and related devices
    • Electrical Engineering
3
Replies
73
Views
7K
How to calculate Carrier Concentration vs. Depth from a CV measurement?
    • Electrical Engineering
Replies
1
Views
1K
Fully differential opamp for impedance matching
    • Electrical Engineering
Replies
18
Views
4K

Hot Threads

Recent Insights

Back
Top