End caps and electrical element length

[KeepItSimpleStupid]

This is a dumb question for anybody.

Suppose I had a Yagi antenna and the elements needed to be cut within 2 mm. The original elements are essentially crimped at the end and are made of a rolled tube which won't really hold water.

Now say, I want to replace one of the elements with a tube of the same diameter for whatever reason and want to place protective end caps on the ends so water doesn't get in.

Is the "electrical length" the length of the metal or the length of the metal less the amount covered by the insulator?

Does it matter depending on the element;s function? Reflector, director or driven element.

Example pic: **broken link removed**

 

[RadioRon]

The end cap is likely a type of plastic, with a dielectric constant that is larger than that of free space. So, in theory it will have the effect of making the portion of metal that it covers slightly longer, electrically speaking. However, this effect will be tiny enough that you can ignore it. For this reason, the electrical length is effectively that of the metal, all of the metal.

 

[4pyros]

The plastic caps should have no effect on the element length.

 

[MikeMl]

The plastic caps should have no effect on the element length.

Actually, better said that you wont be able to notice the effect of the plastic caps.

 

[4pyros]

Actually, better said that you wont be able to notice the effect of the plastic caps.

Thanks Mike.