Amateur Radio

1114 readers

22 users here now

General amateur radio (ham radio) chat, questions, and news

founded 2 years ago

MODERATORS

[email protected]

Which side of this dipole is ground? (programming.dev)

submitted 3 weeks ago by JackbyDev to c/[email protected]

12 comments fedilink hide all child comments

My guess

The left sort of looks like the outside of the cable so I think that's ground.

you are viewing a single comment's thread
view the rest of the comments

[–] JackbyDev 2 points 3 weeks ago (2 children)

Let me rephrase (your answer may be the same). I know with some antennas there is a "ground plane" type of element that should be on the bottom. For a vertical dipole is this not the case?

[–] [email protected] 3 points 3 weeks ago (1 children)

You do seem to be right. It should not matter in theory, but it may be better for the one connected to the center (right on this image) to be up.

For vertical polarization, in theory it does not matter which way around you orient the antenna as long as it's vertical. However in practice, you may get slightly better results by having the element connected to the center coax conductor pointing UP.

Source: https://www.rtl-sdr.com/using-our-new-dipole-antenna-kit/

[–] JackbyDev 1 points 3 weeks ago (1 children)

Weird that they don't elaborate. I flipped it last night and it seemed marginally better this way, so maybe there is some truth to it. Take this with a truck load of salt as it wasn't any sort of controlled experiment at all.

[–] [email protected] 1 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

in your antenna, the outside of the coax makes up part of the radiating structure. The orientation of the elements in relationship to that coax will definitely change the radiation pattern, maybe for the better maybe for the worse.

putting ferrites around the coax right below the antenna feed point will make the antenna more symmetrical as it blocks RF currents traveling back down the outside of the shield.

[–] JackbyDev 1 points 3 weeks ago

It has a choke on it, it's a little blurry but you can see it. Should it be moved closer? I saw a comment on rtl-sdr's blog suggesting it.

[–] [email protected] 1 points 3 weeks ago

It does not matter. (It does not matter in a “ground plane” antenna either, the radials have nothing to do with the earth other than being easier to mount with the coax heading downward; in fact, radials should not be touching or buried in the earth as they are RF radiators and RF faces high losses in soil)