Damn Toll_Free , good to see you back on the board ......only for a quicky ? Bring it on dude ! Peace
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Avanti Sigma4: An alternative view point
- Thread starter bob85
- Start date
B
BOOTY MONSTER
Guest
someone on here used to have a pic in their sig of something that looked kinda like a sigma 4 but the grounds were paralle to the the main element and had some kinda square pannels at the top and bottom of the geounds with the main running up the center of it . if someone knows what im talkong about and can post the pic id be thankful .
anyhow , i was wondering if its just another way to make a sigma 4 , and what the differences in their performances are .... ?
anyhow , i was wondering if its just another way to make a sigma 4 , and what the differences in their performances are .... ?
not sure which antenna you mean booty unless its this one
Geez never seen that monkey before Bob. What is that? Bottom radials a vertical close-in ground plane? Interesting. Manufactured? Homemade? Is it a 1/4 wave or 1/2 or something else?
QSL. Can't see the top in the pic so couldn't judge the length. Guessing is for 2 meters?
Seen relatively similar all aluminum J Pole for 2M/440 with a matching stub.
TNX
Seen relatively similar all aluminum J Pole for 2M/440 with a matching stub.
TNX
B
BOOTY MONSTER
Guest
thats it Bob . thank you 
i dont see any gamma or other tuning system so im guessing its tuned by adjusting the length of the elements ??? and for some reason i suspect that if the ground elements arnt spaced exactly right all around the radiator that it throws everything out of skew ??
so its not like the sirio sigma 4/vector/LW150 .
i dont see any gamma or other tuning system so im guessing its tuned by adjusting the length of the elements ??? and for some reason i suspect that if the ground elements arnt spaced exactly right all around the radiator that it throws everything out of skew ??
so its not like the sirio sigma 4/vector/LW150 .
no its not the same as a sigma but similar,
the monopole is isolated and direct fed at its base, unlike the sigma style antennas you are stuck with a 3/4wave monopole,
theres a good explanatioon of how they work in the arrl under open sleeve antenna,
its not a j-pole .
the monopole is isolated and direct fed at its base, unlike the sigma style antennas you are stuck with a 3/4wave monopole,
theres a good explanatioon of how they work in the arrl under open sleeve antenna,
its not a j-pole .
I have a i-25k and have yet to be beat by any sirio antenna 5/8 wave or 3/4.
5l8 wave is the way to go.Read the arrl hand book.
5l8 wave is the way to go.Read the arrl hand book.
Common sense suggests that if you needed the I-25K over the I-10K, then of course no other CB groundplane is going to beat you. The I-25K has advantages with high power, low RFI, and extreme weather durability. It has no more gain then any other well designed 5/8 wave and less then the Sigma design never studied by the ARRL. That was proven more then 30 years ago on a test range in Illinois.
I'm still unsure.
Near field tests often mask what real world long-range tests reveal. Are you certain the TOA on the Avanti design beats the 5/8 for distant ground wave performance?
In my limited experience the .64 outperformed the Larry's to stations about 40-75 miles away, all things being ~equal.
I still want to try the 30 footer with the enlarged ring. I wish I could get specific and detailed gamma match specs.
Near field tests often mask what real world long-range tests reveal. Are you certain the TOA on the Avanti design beats the 5/8 for distant ground wave performance?
In my limited experience the .64 outperformed the Larry's to stations about 40-75 miles away, all things being ~equal.
I still want to try the 30 footer with the enlarged ring. I wish I could get specific and detailed gamma match specs.
I'm only certain because working in my field has given me the opportunity to replace hundreds of 5/8 wave antennas with the Sigma design on every frequency from 26 MHz to 160 MHz. In every application is beats the 5/8 wave in the only area that matters, far field signal gain. Many of these applications were on FM where most of the receivers did not have a signal meter. The Sigma design makes the most difference when compared to the original 5/8 waves fringe coverage area that contains lots of white noise. Typically we see at least an increase in range that would turn the original fringe coverage area into useable coverage area with nearly no white noise unless the signal is obstructed in some direction.
Don't waste your time with the expanded loop. It's likely that more gain can be had with the extra radial length that the new Vectors are being built with. I see that on FM and Bob85 has seen the same on 11 meters. Just buy the Vector for the $150 on eBay. You can always beef it up mechanically with some hose clamps on slotted sections and some longer tubing to replace the thin top whip.
Don't waste your time with the expanded loop. It's likely that more gain can be had with the extra radial length that the new Vectors are being built with. I see that on FM and Bob85 has seen the same on 11 meters. Just buy the Vector for the $150 on eBay. You can always beef it up mechanically with some hose clamps on slotted sections and some longer tubing to replace the thin top whip.
CDX-007, in the body of your post above you say,
Which antennas did you actually compare? Did you record any of your observations that you can show us when you compared your antennas?
Below with the picture you show us a Hy-Gain Penetrator 500 and tell us it's a .64 wl, and a Interceptor I-10K that is .625 wl. Personally I don't think this wavelength issue makes a difference that most CB'rs can measure or even tell using our radios. My files show that there were several different P500's made over the years. The manuals all show them to be 5/8 waves and are 22'6" to 22'9.5" long, not including the top hat measurements. I figure maybe the P500 might have changed a little when the 40 channel radios came out, but I see no references to their being .64 wl long.
Can you show us a link to the any info showing the Penetrator 500 is a .64 wl antenna?
There are a couple of locals that run the vector antenna my i-25k not only out performs them on transmit but their antennas also have interference problems.which mine does not.This is with equal power to what ever they are running.And yes im in a great location but some of the stations we compared signals to were not in locations in my favor.