What kind of Antenna

[BaLa]

What kind of antenna is this?

http://users.cablemo.net/~balakov100/public_html/Pics/100_0838.JPG

can't see the top element really well..
I think it's some type of discone?


belongs to the neighbor btw

 

[flyingwolf]

Looks like a homebuilt. extremely low frequency discone.

Probably HF

 

[AndrewC75]

That looks like a base CB antenna... I'm sure it's a fairly generic design, but I remember there being one named a "Star"-something-or-another.

 

[fourwd1]

Yeah, it's an old Antenna Specialist's CB ant (or was it Avanti Astro-Star ?)
Anyway, CB ant.

 

[KD5NVE]

Antenna

That is an astroplane

 

[JackTV]

The picture is not that good but to me it looks like a Starduster CB antenna. By the way It was a great omni for CB.

Jack

 

[flyingwolf]

How could I have forgotten CB lol.

 

[kb2vxa]

Hi BaLa and all,

It's a CB antenna alright, a groundplane to be specific. The Star Duster was a 1/2 wave radiator (18') with rather short radials and it's not the Avanti Astro Plane (a modified ground plane) which had a hoop at the bottom, very short vertical section with a small horizontal cross at the top. I remember that one well, I know a guy who replaced his Rat Shack ground plane with one and thanks to Mrs. Roman (I'll never forget her, hi.) was immediately dubbed the TVI-O-Plane! Oh, there was no noticible difference in transmit or receive so he put the RS back up and, well, I won't tell you exactly HOW the Astro was returned to the dealer. (;->)

Now if you want to know what the brand name was/is, ask the CBer at the bottom end of the coax.

"He'll ride the Astro Plane, give you trips around the bay, bring you back the same day, Timothy Leary."
Timothy Leary Is Dead, Moody Blues (with a slight twist).

 

[Al42]

It's a CB antenna alright, a groundplane to be specific. The Star Duster was a 1/2 wave radiator (18') with rather short radials

Since when does a 1/2 wave radiator need radials, Warren? A matching network, yes, but radials? For what - to distribute the microwaves evenly?

 

[BaLa]

thanks guys..

I was just curios, I thought that he was a scanner nut also.
Guess not :lol:

 

[kb2vxa]

Hi Al42 and readers,

"Since when does a 1/2 wave radiator need radials, Warren?"

When it's a half wave groundplane.

 

[kirka127]

that is a 5/8 wave starduster.

 

[Al42]

Hi Al42 and readers,

"Since when does a 1/2 wave radiator need radials, Warren?"

When it's a half wave groundplane.

Care to describe (mathematically) what "a half wave groundplane" is?

If you feed a half-wave vertical radiator from one end you have a ~5000 ohm antenna that doesn't need a counterpoise, because it's a whole antenna. If you feed it from the center it's ~73 ohms, but it's still a whole antenna so it needs no counterpoise.

How do you design a half wave vertical radiator so that it's only half an antenna (which is the only kind that needs a counterpoise)?

 

[kb2vxa]

Hi all,

Re kirka127:
"that is a 5/8 wave starduster."

5/8 wave at 27MHz is 21' and the only such antenna was made by Avanti, I don't remember what they called it. Many manufacurers advertized 5/8 wave antennas but they were either 1/2 wave or slightly longer actually. (CBers will swallow anything, hi.)

By way of explanation .... .. (HI) is Morse for laughter.

Re Al42:
"If you feed a half-wave vertical radiator from one end you have a ~5000 ohm antenna that doesn't need a counterpoise, because it's a whole antenna. If you feed it from the center it's ~73 ohms, but it's still a whole antenna so it needs no counterpoise."

Agreed.

"How do you design a half wave vertical radiator so that it's only half an antenna (which is the only kind that needs a counterpoise)?"

THAT you'll have to ask the design engineers at Antenna Specialists who designed the first one with 1/4 wave radials, the Super Magnum. Taking an educated guess, it was to reduce the vertical take-off angle giving it a bit of gain. BTW, "half an antenna" I suppose means 1/4 wave but it's not the only one that needs a counterpoise. The 5/8 wave antenna needs a counterpoise, I used one on the "base" for 2M and another on the mobile where the roof of course takes the place of the radials. Increasing the length of the radiator (to a point) lowers the vertical radiation angle increasing gain which is why they're so popular.