Antenna question

[Nick23]

Recently, I have been reading up on antennas. I have read that top loaded antennas are the most efficient. Then middle coils and lastly base loaded antennas. Why do the majority of people use Wilson 1000 or 5000's if a top loaded antenna is supposedly better and more efficient? I know people want to put some watts into their antennas, but a 4ft fiberglass top loaded antenna can handle most of what people are running.

Explanations, comments?
Thanks for some input regarding this matter.

 

[Captain Kilowatt]

For a given length of antenna the further up the loading coil is the greater the inductance required to achieve the same degree of loading. This means that a top loaded antenna will require more coil than a similar length base loaded antenna. This also means a heavier load at the top and lower power handling ability due to the possibility of corona discharge and narrower bandwidth.

 

[M0GVZ]

Recently, I have been reading up on antennas. I have read that top loaded antennas are the most efficient. Then middle coils and lastly base loaded antennas. Why do the majority of people use Wilson 1000 or 5000's if a top loaded antenna is supposedly better and more efficient?

Because they're mobile antennas and top heavy mobile antennas don't fare so well driving down the road at 70MPH.

 

[Lil'Yeshua]

Delete

 

[Nick23]

I'm not talking about performance outside CB and ssb. I was just wanting a little clearer picture regarding some info companies are saying.

Thanks

 

[Captain Kilowatt]

I'm not talking about performance outside CB and ssb. I was just wanting a little clearer picture regarding some info companies are saying.

Thanks

Good luck on that. Companies will say whatever they think will sell more of their product. Antennas are no exception and actually contain a lot of misinformation and sometimes just plain bullshit. It is up to the buyer to be well informed with actual facts and not just "My buddy said that....... so I want one too." My favorite antenna selling point is Jo Gunn's claim of audio gain. :headbang that rates right up there with a "colour TV antenna". :sneaky2:

 

[space cowboy]

because the firestick won't bend under the garage door.

 

[Nick23]

Good luck on that. Companies will say whatever they think will sell more of their product. Antennas are no exception and actually contain a lot of misinformation and sometimes just plain bullshit. It is up to the buyer to be well informed with actual facts and not just "My buddy said that....... so I want one too." My favorite antenna selling point is Jo Gunn's claim of audio gain. :headbang that rates right up there with a "colour TV antenna". :sneaky2:

Funny thing is that cbradiomagazine, wearecb.com and a few other non bias company websites are all saying the same thing. Top loaded antennas are more "efficient".

 

[Captain Kilowatt]

Funny thing is that cbradiomagazine, wearecb.com and a few other non bias company websites are all saying the same thing. Top loaded antennas are more "efficient".

They are more efficient if you compare the same length of antenna and try base,center, and top loading. There are many variables however like the size of wire used to make that coil. Larger wire is better as it has lower losses. Also the difference in efficiency tends to be something that is measured in fractions of a dB making the difference very real however very minute and not really detectable in normal use. Again another selling point that while true actually means nothing to the well informed. The difference in loading coil position also tends to affect the angle which the RF leaves the antenna and this may appear to be a good thing or a bad thing depending on the signal path.

 

[Nick23]

Okay thanks. In the real world no big difference, but technically they are more efficient.

 

[Beetle]

Okay thanks. In the real world no big difference, but technically they are more efficient.

If you have a laboratory full of good, calibrated test equipment you would probably be able to detect the difference. Otherwise, you'll never see it.

 

[M0GVZ]

Funny thing is that cbradiomagazine, wearecb.com and a few other non bias company websites are all saying the same thing. Top loaded antennas are more "efficient".

For a shortened antenna, top loaded is because it increases the current flowing in the antenna.

However from a practical point of view they make poor mobile antennas if you actually plan on driving with the thing on.

 

[Captain Kilowatt]

Several manufacturers made top loaded fiberglass antennas that were not an issue driving at highway speeds due to the rigid fiberglass shaft however the antennas were wound with small wire making for higher losses which would offset the higher efficiency. In fact most all fiberglass antennas you see on big rigs are top loaded in this fashion. Top loadibg a steel whip antenna makes for a rather unwieldy thing on the highway. Many years ago I believe it was Antenna Specialists that made a set of center loaded antennas that worked quite well however the bottom whip was really heavier with a smaller lighter whip above the "can" type loading coil.