2 meter sigma 4

[bob85]

vo1ks
what you claim is in argument with what CEBIK told me about that style antenna,
can you explain the theory of operation including antenna mode and transmissionline mode currents as explained in the open sleeve article in the arrl handbook

claims without technical explanation AND a link to reference material that supports the claim are meaningless waffle popular with the j-pole camp.

 

[vo1ks]

Right. I've had it pounded into me that every watt of RF and fraction of a dB is important. Pfft... Drop your output power by half (-3dB) and no one listening will know the difference. The only people who will know any different are those looking at a transmitter wattmeter or those paying the power bill. A change in antenna gain of a fraction of a dB is utterly and totally irrelevant. For simple antennas such as being discussed the change in angle is insignificant. Put up a 16 bay antenna and beam tilt can become an issue. The narrow beam pattern can easily be sent well above the intended direction if the individual elements are not phased properly. But for the half wave (or 5/8 wave) vertical being discussed this certainly doesn't apply.

If you're happy with a fancy looking antenna, like colorful pictures, and hyped numbers then have at it. Some people dazzle with brilliance, others baffle with bullshit. It can often be hard to tell the difference.

 

[Wiskey Delta-40]

HEY !

this thread was started as a "LOOK" My neighbour scratch built a sigma 4 for the 2 meter band and that it works GREAT

NOT a pissing match between a couple people :bdh:

 

[Captain Kilowatt]

I could build an antenna with 60dB gain quite easily. It's not difficult to scam test results, and without knowledge of the reference being used any numbers are irrelevant.

Exactly! Most published CB antenna gain figures (and some ham antennas too) are not really measured but rather conjured up in some back room somewhere under the cover of darkness. To the uninformed these gain figures look wonderful but then you dig deeper and find out that ground gain has been added (some as high as an additional 8 dB) and then the just plain BS factor of another couple dB or so and before you know it you have a half wave vertical antenna claiming a gain of almost 10 dB over..........................well just exactly what is it over? A halfwave dipole? LOL Regardless of how well most antennas perform there is indeed a great deal of false hype surrounding the gain figures and overall performance. remember the hype about installing a Francis mobile whip at the top section of an A99 or the older Shakespeare Bigstick? The claim was that it increased the gain to almost 14 dB. Uh-hunh......hype.

I could consider it an interesting looking antenna, but nothing at all like some of the large dipole arrays at RCI in Sackville, NewBrunswick.

Can you still get tours of that place Warren? I know there is not much there other than transmitters and antennas, switching as all programming is via satellite I believe but every time I go up that way I keep thinking about dropping in.

 

[Captain Kilowatt]

HEY !

this thread was started as a "LOOK" My neighbour scratch built a sigma 4 for the 2 meter band and that it works GREAT

NOT a pissing match between a couple people :bdh:

Welcome to the world of internet forums.

 

[vo1ks]

Ah, but of course. And a fine looking antenna is it.

HEY !

this thread was started as a "LOOK" My neighbour scratch built a sigma 4 for the 2 meter band and that it works GREAT

NOT a pissing match between a couple people :bdh:

RCI still offers prearranged tours as far as I know. The Halifax club had a tour about two years ago. There are a pair of 350kW transmitters, several 100kW, and a couple 50kW from what I recall. It uses 150 ohm balanced line to the antenna switching building. Interesting place to visit.

 

[Se7en]

i bet my home brew jpole will smoke that slim down cut to size cb jack off 2m antenna

 

[Captain Kilowatt]

i bet my home brew jpole will smoke that slim down cut to size cb jack off 2m antenna

Perhaps..................if you can figure out which end to feed it from.

 

[HomerBB]

Changed my mind.

 

[vo1ks]

I had good results with a 2M coaxial dipole, essentially the same as a Shakespeare Big Stick. It was built with a mobile through roof 1/4 wave antenna, whip mounted on a half round plastic thing. The outer sleeve was 1-1/2 inch copper pipe. The inner mast was 3/4 inch copper pipe. There were two teflon spacers keeping the mast and sleeve straight. At the top I soldered a piece of flat copper to them both and trimmed the outer edge. Drill a hole in the center and pop the mount to it. Should try to find it again and get it put up somewhere...

 

[Captain Kilowatt]

I had good results with a 2M coaxial dipole, essentially the same as a Shakespeare Big Stick. It was built with a mobile through roof 1/4 wave antenna, whip mounted on a half round plastic thing. The outer sleeve was 1-1/2 inch copper pipe. The inner mast was 3/4 inch copper pipe. There were two teflon spacers keeping the mast and sleeve straight. At the top I soldered a piece of flat copper to them both and trimmed the outer edge. Drill a hole in the center and pop the mount to it. Should try to find it again and get it put up somewhere...

From what I saw and what you told me about your storage I guess we won't be seeing it anytime soon hey? :laugh:

 

[vo1ks]

It was two houses ago and hasn't seen RF for well over 10 years... I built one for a low power FM station and it performed very well. Easy to make another one, just need to find the parts.