"Name Brand" Mobile antennas, really "better"?

[radioreddz]

I always thought the 102"whip was the ultimate mobile antenna and all the others with their center loads,bottom loads and coils were just trying to be like 102"whips and use the gimmicks to make up for their lack of length for those that can't run the full 102". I myself run the sirio on couple vehicles and preditor 17" shaft 10k on the other and see no real kick "A"ZZ difference between them. I remember the base loaded antenna wars between the antenna antenna specialist big mama trunk mount the turner signal kickers and the rat shack trunk mounts then came the Wilson 1000 and the K40 both boasting longer whips out the top of the coil then you have sirio with even a longer whip all just again trying to be 102" whips. it's all in the length. just ask your girlfriends do they think longer is better.

 

[959]

yup

just go with a Wilson 1k or 5k and you will be happy they are for the non power hungry people I run 1k with mine and it works just fine and it should be good for you too

 

[mr_fx]

in all truthfulness a 102 whip is no as good as you might think... yes it is a full 1/4 wave antenna... BUT it's made out of 17-7 stainless and is rather lossy above 21MHz or so... however if it was made out of 304 stainless the permeability would be nearly the same as copper, and the antenna would act about like copper... or you could nickle plate, then copper plate the nickle...

as for the coil antennas... a bigger base section is better... thinner wire, 10-12 gauge, maybe as thick as 8... and keep the metal of bottom section and whip as far away from the coil as you can get away with

the center insulator should be made out of Delrin as nylon (which is what most of the guys are using) gets pretty hot at around 500 watts @ 11/10 meters

It would better if the bottom section (MAST) was made of copper instead of aluminum, and the coil was made of coated copper or even silver plated wire...

I am willing to bet that a 'coil' type antenna will out perform a 102 in most cases, simply because the 102 is rarely tuned and more importantly because the 102 is likely to be mounted in a less than optimal location, IE beside the counterpoise (your car's body) and the coil antenna stands a higher chance of being mounted on top of the car, therefor giving it a nice ground plane to work against...

 

[mr_fx]

heck, anyone else remember the (manuf. promoted) rumor around the early '80's about a certain antenna having so much gain that it was illegal.

actually I think that was kinda true in the UK... center and top loaded antennas were illegal for a period of time... read something about that recently

 

[W5LZ]

Can a 'coil' antenna be as good as a simple 1/4 wave antenna? Sure, depending on a lot of things. In every case? Nope, sorry. It's the whole thing, not just part of it. Mount them both in the same location, under the same conditions, and the 1/4 wave is going to come out ahead. Is the difference going to be 'earth shattering'? Nope. And depending on how you measure the difference it probably won't even be noticeable, maybe.
In general, meaning it won't be an absolute, the 1/4 wave will beat a 'shortened' antenna of any kind. Maybe not by much, but on an average, yes. If the difference isn't objectionable for some reason, take your pick...
- 'Doc

 

[vkrules]

Can a 'coil' antenna be as good as a simple 1/4 wave antenna? Sure, depending on a lot of things. In every case? Nope, sorry. It's the whole thing, not just part of it. Mount them both in the same location, under the same conditions, and the 1/4 wave is going to come out ahead. Is the difference going to be 'earth shattering'? Nope. And depending on how you measure the difference it probably won't even be noticeable, maybe.
In general, meaning it won't be an absolute, the 1/4 wave will beat a 'shortened' antenna of any kind. Maybe not by much, but on an average, yes. If the difference isn't objectionable for some reason, take your pick...
- 'Doc

I agree ,but most of the 1/4 wave's I see here ( in VK )are mounted on the bumper, or worse still the tow hitch. The loaded antenna usually end up on the guard or roof. That equals the playing field.Still it's hard to get through the bigger and more expensive the better mentality!.

 

[The DB]

in all truthfulness a 102 whip is no as good as you might think... yes it is a full 1/4 wave antenna... BUT it's made out of 17-7 stainless and is rather lossy above 21MHz or so... however if it was made out of 304 stainless the permeability would be nearly the same as copper, and the antenna would act about like copper... or you could nickle plate, then copper plate the nickle...

Any suggestions for a test that I could do at home to confirm/deny this? I've heard some people say stainless steel has so much more in losses than copper at these lengths, and others who clearly disagree. I, personally, tend to be with the others typically, but would love to test this to be sure if possible.


The DB

 

[w9cll]

If you want to test antenna's then mounting them on your vehicle is the worst idea to start off with. Take a pole, pound it in the ground, mount a 3/8x24 mount on it and make sure its in a open area. Run some ground radials under it, 15 or 16 should be good enough. Mount each antenna and check the SWR with either an reliable meter (not the one in the radio)or analyser. Have a friend or someone trustworthy check the signal from about 3-5 miles away. Switch antennas back and forth till a plot can be determined. I am sure you will find that most if not all will be within less then a 1/2 s unit of a 1/4 102" whip.

Now the one that works the best in that test mount on the car making sure there is metal UNDER the antenna not next to it. See how your performance is with that antenna.

 

[W5LZ]

If you're talking about the conductivity of stainless steel, there isn't enough difference to make any difference at all. It's other physical characteristics more than make up for it anyway. You can abuse stainless steel orders of magnitude more that copper for instance.
- 'Doc

 

[The DB]

I am in agreement with doc on the conductivity of stainless steel in antennas. I just figured that enough people seem to believe otherwise that a test could show what is what.


The DB

 

[mr_fx]

If you're talking about the conductivity of stainless steel, there isn't enough difference to make any difference at all. It's other physical characteristics more than make up for it anyway. You can abuse stainless steel orders of magnitude more that copper for instance.
- 'Doc

YEP! very true kinda like how we use aluminum in our beams, even though copper is better as a conductor of RF, aluminum is cheaper, lighter, somewhat more flexible

 

[mr_fx]

I am in agreement with doc on the conductivity of stainless steel in antennas. I just figured that enough people seem to believe otherwise that a test could show what is what.


The DB

This should explain it a bit...

Conductive Materials or Metal Conductivity - TIBTECH innovations -

Skin Depth Equation Formula (aka Skin Effect) - RF Cafe

 

[M0GVZ]

The biggest difference isn't who makes what or whether its a 1/4 wave or a 5/8 wave etc but where its loaded.

Radiation intensity is proportional to current radiated in the antenna. In a base loaded one the current is low and spread equally over the antenna. In a centre loaded antenna the bottom section has a high current flow and the top section a low one. In a top loaded antenna high current flows throughout the whole antenna.

As driving down the road with a top loaded antenna isn't going to happen, centre loaded is the next best and there's a lot of centre loaded antennas around.