why would a ham say this ..... ????

[BOOTY MONSTER]

WB6BYU over at the eham forum said this .......

"If the difference among any such antennas (including a quarter wave ground plane, 5/8 wave, J-pole, A99, or the antenna described here) is measurable, then it is most likely due to high losses in the materials or common mode current flowing on the coax or mast that distorts the pattern:* you can make such antennas WORSE than a standard dipole if they aren't built right, but you can't make them perform any BETTER than one, regardless of the materials and work you put into it."

http://www.eham.net/ehamforum/smf/index.php/topic,75921.msg521877.html#msg521877

my 1/4wgp vs. 5/8wgp results clearly show me there can be big differences !!
and this guy has over 8000 post .
but we all know a high post count does not mean someone is a good source of accurate info . still kind of surprising though .

 

[KE3W]

You got to admit though - his explanation sounds like one of the Doctor's on the Casey Trial explaining their DNA findings!

 

[Marconi]

Hey Booty, you didn't quite get WB6BYU's quote correct. Why don't you try and read the full statement for what was really said,

 

[RatsoW8]

You kind of summerized what he said but his remarks are spot on. In the world of CB, performance is measured in terms of hearsay and hype. Bigger coils, more complicated arrangements of aluminum tubing are though to be the best performers. But, at the end of the day a 1/4 wave gp, 5/8 wave gp, etc are just that and nothing more. I can buy the most expensive and complicated 1/4 wave gp out there and it will work no better that a 1/4 wave wire and two wire radials hung from a tree. There's no magic to how antennas work.

 

[BOOTY MONSTER]

Hey Booty, you didn't quite get WB6BYU's quote correct. Why don't you try and read the full statement for what was really said,

you are correct sir (again)

WB6BYU pointed out what i missed .....

"If you read my comments carefully you'll see that I was comparing antennas with the same TOP
height, not base height. The only reason that a 5/8 wave antenna has an advantage over a
1/4 ground plane with sloping radials is if the bases of the antennas are at the same elevation,
in which case the point of maximum radiation of the 5/8 wave antenna is higher above the ground."

and this is my reply....

"thank you sir for clarifying your comment that i didn't give the proper attention too . a very helpful gentleman named Marconi over at WWDX has posted lots of charts from his experiments over the years and typically sees little difference between antennas with their tips at the same height . my results from comparing a 1/4wgp and a 5/8wgp were with the feedpoint within 2 feet of each other . a 30 ft mast is as high as i could possibly go here because it would need to be guyed beyond that . im a renter and the home owner has said running guy wires across the house and yard is a no-no . so for my circumstances the taller antenna at the same feedpoint is my most effective option , as far as an omni antenna goes . no doubt a beam antenna would do better . i do hope to build a 3 or 4 element beam at some point , but that will be quite a bit down the road .

thanks again for your helplful and kind comments ."

 

[HomerBB]

It's all straightened out in only 5 replies! :blink:

What is this forum coming to . . .?

 

[Marconi]

BM, I have an explanation for why WB6BYU might make such a claim.

I agree with the technical claims noted in the following two graphs. In fact I think this is probably the accepted scientific fact regarding antenna gain.

However, most ignore the descriptive captions associated with each graph depicted, and that has lead to a considerable amount of ill-conceived ideas by most CB operators about vertical antenna gain and most manufactures include these ideas to help support the outlandish claims.



In the images noted below, Bob85 uses his EZBob software to describe the basic patterns for several different designed antennas, and it is to be noted that for each...the top most radiating portion for each is a 1/2 wave pattern where the maximum RF is generated.

So, if all these antennas were positioned whereas the antenna bottoms were all at the same height, the basic differences would be in the ultimate height of their respective 1/2 wave portions. That height difference should or could manifest a modest difference in net gain to the horizon. The notations for VN indicates a maximum Voltage node, and CN indicates a maximum Current node.



IMO, this idea is basic and fundamental to all vertical antennas and has to be considered in order to understand why a Ham operator might make such a claim as suggested by Booty Monster's question.

 

[C2]

radiation occures at maximum current.

Considering ground affects, a dipole is about 8dBi and a 5/8 wave is about 1.2 dBd, at max.

larger differences can be seen at specific radiation angles, but in general there is not much difference overall.

The systems are somewhat sensitive anyway, so you may not actually see ideal gain in any design, and I suspect that most systems are not performing any better than a plain old dipole, properly mounted and fed.

Another question, how is anyone able to accurately measure antenna gain in a real world environment with any appreciable certainty in their results? - you can't!

 

[W5LZ]

Measuring antenna gain is possible, but not for the average person. It requires some specialized equipment. Wish I could afford that stuff but I seriously doubt I could even if I won the lottery.
- 'Doc

 

[BOOTY MONSTER]

thanks ole' grandpa
my point of view is if you can do 10 ft or 100 feet , why not use the most effective you can at your maximum possible feed-point . of course that would be a big beam .

so ........ if tip height is equal between a starduster and a sigma 4 the sigma should do no better unless there's a problem with the starduster ?
what about TOA and signal on the horizon ?


"It's all straightened out in only 5 replies!"

you should know by now every answer i get causes new questions

 

[Robb]

The prime feature of the 5/8 wave gp or Sigma IV/Vector 4000 - is to have a low angle of radiation. So, frankly I cannot reason why this fellow would say that there is little difference. Low radiation angles are certainly far better off that higher angles of radiation provided by the 1/4w gp or 1/2w gp.

Surely, the difference between antenna theory, the drafting board/design, the materials used, and assembly does not guarantee that every antenna is going to be as efficient/loss-less and equal as simple theory would dictate.

 

[BOOTY MONSTER]

when i tested my first 5/8 eight ft off the ground in the front yard at the other place it was about 30 1/2 ft to the tip . the 1/4 wave befor it was about 26 ft to the tip . there was a huge difference between the two with the 5/8 being better on both tx and rx . there was some improvement over the 5/8 at 30 1/2 ft when the 5/8 was raised up to about 38 1/2 ft to the tip , but certianly not as much as initally going from the 1/4wgp to the 5/8 .

but maybe there was something wrong with my 1/4 wave ....... :blink:

 

[C2]

Low radiation angles are certainly far better off that higher angles of radiation provided by the 1/4w gp or 1/2w gp.

That is a generallity that does not always apply. It might be better for most local, not all. It might not be better for DX in general. I say it would generally be a wash.

But I do look purely at the drawing board to determine what's best and work from there. I've discovered that I need more than one antenna in more than one configuration.

 

[hotrod]

when i tested my first 5/8 eight ft off the ground in the front yard at the other place it was about 30 1/2 ft to the tip . the 1/4 wave befor it was about 26 ft to the tip . there was a huge difference between the two with the 5/8 being better on both tx and rx . there was some improvement over the 5/8 at 30 1/2 ft when the 5/8 was raised up to about 38 1/2 ft to the tip , but certianly not as much as initally going from the 1/4wgp to the 5/8 .

but maybe there was something wrong with my 1/4 wave ....... :blink:

bm from what i see here your 1/4 was @ 26 feet to the tip
your 5/8 was 30 1/2 feet @ its lowest point.
if you would have raised the 1/4 w up to 30 1/2 feet
your results probaly would be close to the same considering antenna height
is your friend.imho im starting to think that a 1/4 would be much easier to get
up higher being its lighter.may need to use a tower though so theres no guy wires.
im in the exact same situation as you bm im a renter im allowed an antenna but
no guy wires and 30 feet or so to tip height limit. so now a v4k sitting on the ground
would about cover that for me....lol. OR get a 1/4 wave and get it way up there

 

[W5LZ]

Don't put a lot of credence in the differing height making that much difference between the various 'sizes' of antennas, it just isn't going to even make a typical 1/4 wave into a typical 5/8 wave antenna. Of course height can make some differences, but not that much!
All antennas are compared to either a 1/2 wave antenna or an isotropic antenna for gain references. That certainly does not mean that the 1/2 wave antenna is the one to beat, it's only being used as a standard reference.
I also wouldn't put a lot of faith in 'BYU's posts, they are not all correct. Neither are 'JI's. (Or mine either, for that matter.) As far as the nit-whits, the 'N0' for instance, you are always going to find those kind'a people no matter what you are talking about, and on both 'sides' of the fence. Ignore them.
Seems like it always turns into the same old thing. I'm tired of it.
- 'Doc