Radials on .64 wave vertical - Straight or angled?

[SuperNasty]

Is there any benefit to using radials angled rather than straight on a .64 wave antenna (like an Imax 2000 for instance), if so what are they?

I know angled radials can help bring the impedance down to 50 ohm but the Imax and the likes are already 50 Ohms at the feedpoint (even with no radials whatsoever).

Has anybody tried if an Imax 2000 works better with full size radials that are 45 degrees, 30 degrees or 90 degrees?

Thanks

 

[Robb]

The 45 degree down angle is used to adjust impedance on a 1/4 wave vertical antenna since it has no matching device. Every 5/8 wave antenna on the market has its own impedance matching device, be it a coil/capacitor or a beta match.

 

[The DB]

An imax2000 was not intended to be used with radials. Adding full size radials will at the very least, cause you to have to retune the antenna as simply adding the radials changes both the impedance and reactance present at the feedpoint.

Also don't think angling the radials down will make a big difference over horizontal radials. If it were that effective, or even gave insignificant but noticeable gains all of the commercial antenna manufacturers, especially the high dollar ones, would have been angling radials on said antennas for decades.

As Robb pointed out angling the radials down is a method of tuning a 1/4 wavelength antenna, and so you know, it actually makes the feedpoint impedance higher, not lower. It is little more than a method of better matching a resonant 1/4 wavelength antenna to a 50 ohm feedline, not that the minor drop in SWR makes any real difference.

I think Marconi has done some modeling on this in the past, and HomerBB has made 5/8 wavelength antennas both ways. If I have time later I'll see if I can dig up the threads in question...


The DB

 

[vkrules]

I fitted radials on mine, most noticed difference was that it was a little quieter.I used 1/4 wave wire radials about 45% angle tied down to the roof. (also guys the ant) Don't expect to see a big difference signal wise,if any it would be slight. Search the forum there are pages and pages on this subject.

 

[Captain Kilowatt]

The 45 degree down angle is used to adjust impedance on a 1/4 wave vertical antenna since it has no matching device. Every 5/8 wave antenna on the market has its own impedance matching device, be it a coil/capacitor or a beta match.

My 1/4 wave verticals always had a matching device. The ones made of wire used a pair of wire cutters as a matching device and those made of tubing used a tubing cutter or hacksaw as a matching device. All were used with horizontal radials.

 

[vkrules]

Happy new year it's all over here except for the hang overs.

 

[Robb]

My 1/4 wave verticals always had a matching device. The ones made of wire used a pair of wire cutters as a matching device and those made of tubing used a tubing cutter or hacksaw as a matching device. All were used with horizontal radials.

Yup.
But the poster was referring to CB antennas not ham gear.
You don't talk/listen with the CB any more; do you?

 

[SuperNasty]

Thanks for the info, all understood regarding the 1/4 wave antennas. It would be interesting to see the modelling of the Imax with and without radials, angled or straight.

I came across another forum, copper something? stating that simply moving the Solarcon GPK from 45 degrees to 30 degrees made a large difference, I don't think that is the case and was likely down to propagation changes or something.

There's also the school of thought stating that adding radials to the imax makes absolutely no difference, the best way I guess to test this would be have one with and one without both up at the same time and do an A to B test.

Anyway I am going to test out the imax with 4 horizontal 8ft radials at the feedpoint which actually brings another question up, the bottom 10 inches or so is coax in the imax and solarcon states in their GPK instructions to use the bottom U bolt for the radial bracket, surely the feedpoint is the best place for radials which would actually be at the top U bolt just below the tuning rings? Unless that peice of coax does something else of course.

Anyway I guess it wont do any harm to try it, in the absence of anything else to test it against I guess I'll not know if it actually performs any better or not, it will look good though!

Happy New Year by the way (well it will be in 30 minutes or so here).

 

[Captain Kilowatt]

Yup.
But the poster was referring to CB antennas not ham gear.
You don't talk/listen with the CB any more; do you?

Jesus Robb. Are you sure you have a ham ticket? Don't you know that a 1/4 wave is a 1/4 wave is a 1/4 wave regardless of the frequency? What's the difference between a 1/4 on 11m and 1/4 wave on 10m?

I'll tell you the difference. It's about 5 or 6 inches. Nothing more and nothing less.

BTW show me where I made reference to frequency or time involved.

I said "My 1/4 wave verticals always had a matching device." Had. HAD. HAD Past tense of has. They all HAD a matching device etc.......Unless a 1/4 on 11m has changed over the years my reference is still relevant.

 

[Robb]

Why yes, I do know that.
In your attempt to sharpen your claws, you forgot to answer my question: do you listen/talk on CB any more?

 

[wavrider]

op:op:op:

 

[Captain Kilowatt]

Why yes, I do know that.
In your attempt to sharpen your claws, you forgot to answer my question: do you listen/talk on CB any more?

You wouldn't get cut by claws if you would simply read and respond to the words written and stop adding your own version of those words that are written. You can't do that and that is a major reason you are no longer a moderator on this forum.

The reason I did not answer your question is that the question was COMPLETELY irrelevant.

I made a joke about the matching device used in my 1/4 wave verticals and you somehow changed that into the fact that since I no longer dabbled in CB that my input was either wrong, not wanted, irrelevant or whatever.

 

[hotrod]

Thanks for the info, all understood regarding the 1/4 wave antennas. It would be interesting to see the modelling of the Imax with and without radials, angled or straight.

I came across another forum, copper something? stating that simply moving the Solarcon GPK from 45 degrees to 30 degrees made a large difference, I don't think that is the case and was likely down to propagation changes or something.

There's also the school of thought stating that adding radials to the imax makes absolutely no difference, the best way I guess to test this would be have one with and one without both up at the same time and do an A to B test.

Anyway I am going to test out the imax with 4 horizontal 8ft radials at the feedpoint which actually brings another question up, the bottom 10 inches or so is coax in the imax and solarcon states in their GPK instructions to use the bottom U bolt for the radial bracket, surely the feedpoint is the best place for radials which would actually be at the top U bolt just below the tuning rings? Unless that peice of coax does something else of course.

Anyway I guess it wont do any harm to try it, in the absence of anything else to test it against I guess I'll not know if it actually performs any better or not, it will look good though!

Happy New Year by the way (well it will be in 30 minutes or so here).

yup try it see what happens. id use the lower mount bolt and keep the radials at
a 45 degree angle. see how it. turns out. ive also heard it helps quiet the recieve a lilttle

 

[HomerBB]

my 1/4 wave don't have any radials. it has an automobile under it, though.

pdf of models regarding 5/8 with radials different lengths, and slanted or horizontal.

 

[vkrules]

Very interesting. Homer have you done a plot without radials?