Distance between two arms of dipole 2

[mrkenneth]

I know this is a very trivial question, but I will ask it just for interest's sake.

What should be the distance between the feedpoints of the two arms of a dipole antenna? Is it related to the frequency? Or does it even matter?

How about monopoles?

Thanks in advance!

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[SolderingGunslinger]

If you are talking about a standard run-of-the-mill halfwave doublet, the center should be relatively close together IM (not so) HO. There is an EMF minimum at the center of a .5 Lambda antenna and a current maxima. This holds true whether the antenna is center fed (Voltage Feed)or end fed or Zepp fed (Current Feed).

Now, if you are talking about a two half waves in phase (colinear) antenna, there is an advantage to just having the antenna apetures touch at the center. In the case of a wire antenna, the optimal spacing is on the order of .25 Lambda. An Extended Double Zepp (EDZ) antenna operates as a colinear. The EDZ is a doublet .64 Lambda per side. The inner .14 Lambda acts as an extension of the transmission line widening the spacing between the colinear elements for a slightly higher gain.

So, since there is maximum current and minimum porential at the center of a halfwave doublet, there is less possibility for arcing across the center insulator, therefore closer spacing of the elements is possible.

Whatever your project, may it come out well.

I remain,

The Old Soldering Gunslinger

 

[mrkenneth]

Wow! Thank you for the detailed explanation! So many new terms there!

I ask the question out of curiosity, because I have read anything that addresses the question.

For a typical centre-fed half-wave doublet, should the feedpoints be as close as possible? What factors does the distance between the two arms of the antenna affect?

Should the dipole be 0.5 wavelengths long including or excluding the empty space between the two arms of the dipole?

How about the distance between the wire of a monopole and the groundplane?

Thanks in advance!

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[VEBill]

Applicable link:

http://www.cebik.com/trans/gap.html

 

[mrkenneth]

Thank you VE1BLL for the wonderful link!

Now I have some ready to do.

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Operation Radiation:

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