Wilson antenna advice

[M0GVZ]

Why would it make any difference given they're housed in RF transparent plastic?

Does the fact you can see it make it work any better? Plus the purpose of the coil is to give inductive loading to compensate for a shortened antenna. It doesn't radiate to any worthwhile extent and its only purpose is to cancel out antenna capacitive reactance. It isn't there "to add length to the antenna" or anything else. It doesn't add the "missing" length of the antenna.

The fact it is open or closed from a performance point of view is neither here nor there.

If anyone tells you that open is better than closed, ask them what the coil is there for. If they say "to make up the missing length" then ignore absolutely everything they tell you.

 

[9C1Driver]

I've run both the Wilson mag mount 1000 and 5000 for over 15 years. I find them both to be about the same. Last may I purchased a Sirio pl5000 w/145 mag mount. And I feel that the Wilson antenna can't even come close. I see about 5-15 more miles mobile to mobile over the Wilson everyday. Sometimes more. I started in CB in 1968 and these are the best mobile antenna that I have ever seen. I've tuned it to do both the 10 and 11 meter bands. I gave low a SWR from 26.950 - 28.740. I think you would be well pleased with the Sirio over the Wilson.

Oh come now, 5-15 miles???? The only way you will get magical numbers like that is compare it to a K30. I don't doubt the Sirio might be a tad better but not 5-15 miles better.

 

[GnG8d]

Not trying to bash the sirio... I have always been told closed coil antennas are not better than open.

The biggest reason for using a large open coil antenna is power handling, and I'm guessing >90% of the people using them don't run enough power to justify using them.

 

[GnG8d]

Oh come now, 5-15 miles???? The only way you will get magical numbers like that is compare it to a K30. I don't doubt the Sirio might be a tad better but not 5-15 miles better.

Due to the fact that it takes 4 times the power to double the distance from TX to RX, if he went from 15mi to 30mi at the same power level the antenna would need 6dB of additional gain. But he doesn't say 5-15mi better compared to what or even how the testing was done.

 

[w9cll]

5-15 over a dummy load?

 

[M0GVZ]

Oh come now, 5-15 miles???? The only way you will get magical numbers like that is compare it to a K30. I don't doubt the Sirio might be a tad better but not 5-15 miles better.

Or install the antenna better. A larger magmount means more capacitive coupling which means better ground which means better signal getting out.

It isn't beyond the realms of possibility. Now if he was undoing one antenna and replacing it with the other and seeing that kind of change...

 

[M0GVZ]

Due to the fact that it takes 4 times the power to double the distance from TX to RX

It takes a hell of a lot more than that plus you hit the brick wall of the limit of direct wave caused by the curvature of the earth. On 2m VHF you're looking at around tenfold to double the distance.

 

[GnG8d]

It takes a hell of a lot more than that plus you hit the brick wall of the limit of direct wave caused by the curvature of the earth. On 2m VHF you're looking at around tenfold to double the distance.

Not according to the inverse square law.

 

[boomer111]

Depends on the installation circumstances.

In general though the higher the coil the better.

Actually I like the big coil antennas for bandwidth.

Been awhile but I think back 20 years ago I found that the Predator 10K gave me another 20 channels at each end over the Wilson 1000. Meaning I was under swr of 1:3 for another 40 channels. I could safely run 20 below and 20 above the CB 40 and not worry about the SWR.

Nowadays I am strictly CB 40 channels since I no longer have a SSB radio.

 

[GnG8d]

The correct answer is the one with the longest whip wins outright and then its the one with the biggest coil if the whip lengths are identical as that usually transfers into a higher Q and therefore efficiency.

Actually I like the big coil antennas for bandwidth.

Been awhile but I think back 20 years ago I found that the Predator 10K gave me another 20 channels at each end over the Wilson 1000. Meaning I was under swr of 1:3 for another 40 channels. I could safely run 20 below and 20 above the CB 40 and not worry about the SWR.

I don't even own a mobile antenna right now, and have never owned a large open coil antenna. But you guys are contradicting each other, so I'm curious ....... which is the correct statement?

 

[W5LZ]

A correct answer is that if the antenna is long enough then no coil is needed at all. That's when the antenna is most efficient. Coils, or actually the inductive reactance furnished by a coil allows an antenna to be shortened. That's because that straight old whip has enough inductive reactance to counter act the capacitive reactance present and is then resonant. That length is typically a 1/4 wave length.
A too short antenna has more capacitive reactance than the inductive reactance can 'null' out, that means that some inductive reactance (proper sized coil) has to be added.
All of which is well and good. Something else that shortening of an antenna does is change it's radiation pattern, typically making it 'less' in some dimension(s). The amount of that 'less' thingy is not strictly proportional to the amount/percentage of that shortening, but it's sort of close. Don't expect the same 'coverage' from a shortened antenna that you'd have from a 'full sized' one.
And the 'nastiest' part of it is that a really efficient antenna has a narrow usable bandwidth, it just won't 'stretch' from daylight to dark. Antennas that are not adjustable in some way that have a low SWR several Mhz wide are more dummy load than not. As bandwidth goes up, efficiency goes down, just a fact.
None of this sound like the usual thingys you hear? Imagine that! Why? Mainly cuz' I ain't selling anything...
- 'Doc

 

[The DB]

It looks like they are doesn't it? I disagree with them being contradictory, however.

Overall length affects the antenna's natural bandwidth, the longer the antenna the more bandwidth it has.

The losses that are present in the coil also have an effect here, they make the bandwidth appear wider than it actually is. The more the coil shortens the antenna the more losses are typically present.

Overall length is the big decider when it comes to bandwidth, which is why the Predator mentioned above both has more bandwidth and is also more efficient than the Wilson mentioned above.

Now if both antennas were the same length you could use the bandwidth to determine which is more efficient, but only if they were the same length.


The DB

 

[M0GVZ]

We're not contradicting each other. Bandwidth does not equal better performance and in fact a wider bandwidth antenna often means a lossy one unless its full size. A dummy load is 500MHz or more wide at 1:1 SWR but you wouldn't say it was a good antenna.

The wider the diameter of the radiating element of the antenna or the more lossy an antenna is, the wider the bandwidth.

A wide low SWR isn't necessarily a good thing. Low SWR is not an indication of good performance.

Basically with antennas they have three characteristics, size, efficiency and bandwidth and you can only ever have two out of the three when you are using a compromise antenna. Everybody would like a short antenna with a wide bandwidth and good efficiency however you can't.


Basically draw a triangle.

Label efficiency E, bandwidth B and size S for short.

__E__
B | S

Cover up the one you want and you can only have one of the other two.

You can have a short antenna but you either have to sacrifice bandwidth or efficiency.

You can have a wide bandwidth antenna but you sacrifice length or efficiency.

You can have a very efficient antenna but it has to be long or narrow bandwidth.

 

[GnG8d]

The correct answer is the one with the longest whip wins outright and then its the one with the biggest coil if the whip lengths are identical as that usually transfers into a higher Q and therefore efficiency.

Actually I like the big coil antennas for bandwidth.

Been awhile but I think back 20 years ago I found that the Predator 10K gave me another 20 channels at each end over the Wilson 1000. Meaning I was under swr of 1:3 for another 40 channels. I could safely run 20 below and 20 above the CB 40 and not worry about the SWR.

Maybe I just read this wrong, since boomer111 isn't comparing to an equal length antenna I may have completely misquoted him and his findings may not even belong in the comparison.


M0GVZ is saying that with equal length antennas, the larger coil has a higher Q and narrower bandwidth. So there is a direct comparison that says a smaller coil is more lossy.

I've got myself confused now ........

The losses that are present in the coil also have an effect here, they make the bandwidth appear wider than it actually is. The more the coil shortens the antenna the more losses are typically present.

Larger coil at the same antenna height?

 

[GnG8d]

Alright, I just had an epiphany slopping through the mud feeding horses and looking up at my antenna for it's daily visual.

I don't think it's arguable that a shorter antenna needs inductive reactance to cancel the capacitive reactance. The shorter the antenna the larger the coil in "henries".

When the comparison of identical height and larger coils was brought up, I was thinking larger coil in "weight" or surface area.

So it would seem that more henries would be more lossy, while more weight would be less lossy.

Now I'm really confused :sneaky2: