New 11 Meter Vertical Challenge

[Henry HPSD]

Hello Bill,

fanatic bill, not fantastic...though you migth be hihi


Anyway i think Jack has put uit online.
so for those interested:
http://download.antennex.com/listarch/files/searchlight.pdf

Enjoy the weekend.

H.

 

[W5LZ]

"YES! Usually, if an antenna is wideband, it's because there are construction issues like bad solder joints, corroded or lossy materials, lossy coils etc."

Would you mind explaining you reasoning behind that? I do agree that 'wide bandedness' is a product of inefficiency. So it would seem you are saying that inefficiency is a desirable quality of an antenna? Which is just another very good reason to discount the importance being placed on SWR as opposed to other characteristics that are desirable.
- 'Doc

 

[bob85]

kt4ye.
have you looked at the open sleeve antenna in the arrl antenna book?
it may shed some light on your antenna,

from what i can see of your antenna it looks like the feedpoint impedance is a combination of the end impedance of the monopole ( antenna mode impedance ) in parallel with the impedance at the open end of the sleeve transformed through the electrical length of the sleeve ( transmissionline mode impedance ) like an open sleeve or the ssfm,

does eznec show much current in the monopole above the sleeve ?,
does the antenna show to be resonant x=0 on any frequency?

 

[kt4ye]

FREE Access to article.

After a discussion with the antenneX publisher, he has published my article in the FREE access section.

http://download.antennex.com/listarch/files/searchlight.pdf

A couple of comments re recent questions.

Re efficiency: For ME, an inefficient antenna is BAD. So, if the Searchlight proves to be inefficient, then I'm disappointed. HOWEVER, in some applications, an inefficient antenna that can be used on "any" frequency with minimum or no tuning is/may be "good." An example is a resistively loaded device like the B&W. Crummy ham antenna, but they have sold lots of them for "other" applicatios.

Yes, the Searchlight can be viewed as an assymetric dipole. But an assymetric dipole MUST be fed in the center. And that is not practical in *most* vertical installations.

Also similar to some of the open sleeve designs I have seen. These devices are about 50% larger than Searchlight, since they are -- in effect -- J poles with the J morphed into a cylinder.

Searchlight is NOT the same as a coaxial sleeve antenna since the RF at the bottom of the sleeve is at a VERY high RF potential. And THAT makes it*very* difficult to control common mode currentsm in the feeder.

All the best,

Bill