Base Should I stick it?

[JAF0]

- up in the tree with or without radials?
I'm close to installing a Sirio Vector and was wondering what 4 ground radials from a maco v58 would do for the performance if I added them at the bottom of the vector right underneath the cone hub?
If it would help I can add radials I'll take off the old maco but I would fear they might steal some current the cone needs to offset the deconstructive current in the bottom 1/4 wave of the main radiator.
It could happen today since my climber ordered a sirio for another guy who stiffed him for it and has it still new in box. I guess this is a question best for someone who already modelled it.
Thank you in advance if you know and can help

 

[bob85]

Have a look at the models Henry did, scroll down to
"room for improvement" where he isolates the antenna & adds 4 radials,

http://cb-antennas.com/?page_id=780

 

[Tallman]

Compare the length of the radials and compare the difference between the two. The length and diameter will all affect SWR and radiation patterns.
Use what came with the antenna. I would be more worried about the effect of the tree on the antenna SWR and radiation patterns. Since that antenna does not have radials in the traditional sense, I would not change a thing. I had one of those weird looking antennas back in the day and I hoped some one would steal it or a storm would trash it. It did not work very well for my applications..

 

[JAF0]

Have a look at the models Henry did, scroll down to
"room for improvement" where he isolates the antenna & adds 4 radials,

http://cb-antennas.com/?page_id=780

Wow, what an awesome write-up, many thanks

 

[bob85]

IF it holds up to your weather i expect you will like the antenna,
best performing CB vertical currently available,

when mine goes back up i will be robbing elements from my cushcraft 10-4cd skywalker for radials.

 

[The DB]

I don't see adding horizontal radials helping the vector any. When I add horizontal radials to a vector model low angle gain stays very close to the same. The tuning (this was a model that includes a full and tune-able gamma match) didn't need to be adjusted either. The antenna doesn't seem to put any current into said radials, it is as if the model is ignoring the horizontal radials.


The DB

 

[JAF0]

After an all-day test, I see the same thing on my meter. No improvement at any distance tried.
Guy lines are parachute cord.

 

[JAF0]

I don't see adding horizontal radials helping the vector any. When I add horizontal radials to a vector model low angle gain stays very close to the same. The tuning (this was a model that includes a full and tune-able gamma match) didn't need to be adjusted either. The antenna doesn't seem to put any current into said radials, it is as if the model is ignoring the horizontal radials.


The DB

Did you also try modelling it, as Henry mentioned, at 2-3 wavelengths above ground? Mine is only 36' to the radials.

 

[JAF0]

Well, my climber just dropped off some old antenna parts and I believe one is most of an Avanti Sigma4 and the other are 3 radials from a Joe Gunn Pistol, bent at 45 degrees about 8" out.
I'm liking the metal of the Avanti and I think I'll use it to top off the Vector4k so I can remove that weak soft aluminum rod and ball on top.
So will that make it a Vecma or a Sigtor?

 

[bob85]

DB
im not sure what software Henry used to determine signal strength,
i think he has talked about it on here,

its not almost 2db extra gain as you won't get that from a co-linear like the BIG-MAC or Henry's highlander,
its increased signal strength @ 30km from the transmitter when the antenna is isolated & choked,

i know w8ji said it needs radials, i will find out when i try it,

 

[JAF0]

DB
im not sure what software Henry used to determine signal strength,
i think he has talked about it on here,

its not almost 2db extra gain as you won't get that from a co-linear like the BIG-MAC or Henry's highlander,
its increased signal strength @ 30km from the transmitter when the antenna is isolated & choked,

i know w8ji said it needs radials, i will find out when i try it,

I thought the cone WAS the radials?

 

[Marconi]

Here is an old Vector 4K model I did with 4 x 109" horizontal radials vs. no radials.

I see a significant disadvantage in adding radials, but I don't know if the differences would be noticable on the air. The currents noted on these radials are very small in magnitude.

No attempt at matching was done on these models, but you will notice the match is not bad considering my placement of the (feed point) source.

 

[JAF0]

Here is an old Vector 4K model I did with 4 x 109" horizontal radials vs. no radials.

I see a significant disadvantage in adding radials, but I don't know if the differences would be noticable on the air. The currents noted on these radials are very small in magnitude.

No attempt at matching was done on these models, but you will notice the match is not bad considering my placement of the (feed point) source.

Well, I thought there were a couple contacts that weren't quite as strong with the radials as without, but I was hesitant to call it as such because I know atmospheric changes can cause subtle variance in signal strength, especially in distant contacts, and that's what I saw were very subtle changes for the worse with the radials, but almost nearly the same. More same than different.

 

[br549]

one of the best perks about the 4K is it's small horizontal foot print because the ground elements are raised up to create a co-linear effect . some folks have considered it a half wave saying it only radiates above the basket but the link Bob85 supplied would provide evidence that that's not exactly true ...... but marconis results show the opposite . IMO , sometimes where and how the antenna is installed will make more difference than the antenna itself . of course using a good/great antenna to start with greatly improves our odds though .

 

[Riverman]

one of the best perks about the 4K is it's small horizontal foot print because the ground elements are raised up to create a co-linear effect.

When I first found this antenna I thought it was the answer to my prayers for that very reason. With my steeply pitched roof and relatively short mast (15') full-length radials just aren't going to work. However, from what I've heard it doesn't handle strong winds very well and here in Texas we get some humdinger thunderstorms with gale force winds. Often.