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B
BOOTY MONSTER
Guest
mmmmmmmmmm................ that saturn is different . its a " combination verticle and horizontal omni-directional antenna " . if the sigma is a difficult antenna to copy i imagine the saturn could be a bit of a nightmare too .
"i have read different ideas on radials, some say once the antenna is well clear of earth more than 4 is overkill while others claim a rapid onset of diminishing returns after 4,"
thats what ive consistantly read too . i was thinking 8 radials because i can get the materials so cheap (and i have to make a minimum $30 purchase) and that we couldnt have too much ground plane so there would be no harm done and it would let me have something different from other folks .
"based on past experience , some reading and asking cebik, i doubt you will see much improvement playing with radial angle......."
from what i understand sloped vs. horizontal radials really only come into play with 1/4 WGP antennas because sloping them the proper ammount allows them to tune to 50 ohms . larger 1/2 waves and bigger 5/8 and .64's have matching networks so sloping radials arnt necessary for optimum tuning of the antenna . theres also some suggestion that sloping the radials on the bigger antennas makes the overall antenna longer/taller and might possibly give a very slight benefit to the receive of the antenna . that kinda makes sense , but its my understanding that its a very slight effect if detectable at all .
hey marconi , i forgot to mention in my previous post that ill be using solid aluminum rods . they come in 12 ft lengths and i had given a little thought to just using them full length as 1/3 WL elements but ive never herd of a premade or homebrewed single band antenna using anything larger than 1/4 WL (i have read of folks speculating on 1/2 WL ones though) elements and i figgure theres a reason for that . maybe its cost or simply greatly .diminished returns like using more than 4 radials .
so heres my new plan ...........
im still gonna get 8 rods and the plate . ill keep the antennas feedpoint about 10 feet off the ground for most of the month because what im going to do is play with using 4 horozontal , then 4 sloped and then the combo of both 4 horozontal and 4 sloped for a total of 8 elements and see what kind of replies i get from locals on my tx and try to make note of my recieve . ill also try 8 horozontal . skip will be hard to evaulate though , ill have to compare my contact success rate to others nearby . but thatll still be iffy , i know skip conditions can fluctuate from moment to moment and even a few hundred feet difference in location can make or break a contact .. what ever the winner is over that time is what ill stick with . if theres no discernable difference ill probally just use all 8 to be different from other folks since no harm will be done . i will check and if necessary adjust the tuning of the antenna for lowest vswr in each configuration as ill be sure to check to see if one of them tunes better than the others .
Avanti AV-190 "Saturn "
"i have read different ideas on radials, some say once the antenna is well clear of earth more than 4 is overkill while others claim a rapid onset of diminishing returns after 4,"
thats what ive consistantly read too . i was thinking 8 radials because i can get the materials so cheap (and i have to make a minimum $30 purchase) and that we couldnt have too much ground plane so there would be no harm done and it would let me have something different from other folks .
"based on past experience , some reading and asking cebik, i doubt you will see much improvement playing with radial angle......."
from what i understand sloped vs. horizontal radials really only come into play with 1/4 WGP antennas because sloping them the proper ammount allows them to tune to 50 ohms . larger 1/2 waves and bigger 5/8 and .64's have matching networks so sloping radials arnt necessary for optimum tuning of the antenna . theres also some suggestion that sloping the radials on the bigger antennas makes the overall antenna longer/taller and might possibly give a very slight benefit to the receive of the antenna . that kinda makes sense , but its my understanding that its a very slight effect if detectable at all .
hey marconi , i forgot to mention in my previous post that ill be using solid aluminum rods . they come in 12 ft lengths and i had given a little thought to just using them full length as 1/3 WL elements but ive never herd of a premade or homebrewed single band antenna using anything larger than 1/4 WL (i have read of folks speculating on 1/2 WL ones though) elements and i figgure theres a reason for that . maybe its cost or simply greatly .diminished returns like using more than 4 radials .
so heres my new plan ...........
im still gonna get 8 rods and the plate . ill keep the antennas feedpoint about 10 feet off the ground for most of the month because what im going to do is play with using 4 horozontal , then 4 sloped and then the combo of both 4 horozontal and 4 sloped for a total of 8 elements and see what kind of replies i get from locals on my tx and try to make note of my recieve . ill also try 8 horozontal . skip will be hard to evaulate though , ill have to compare my contact success rate to others nearby . but thatll still be iffy , i know skip conditions can fluctuate from moment to moment and even a few hundred feet difference in location can make or break a contact .. what ever the winner is over that time is what ill stick with . if theres no discernable difference ill probally just use all 8 to be different from other folks since no harm will be done . i will check and if necessary adjust the tuning of the antenna for lowest vswr in each configuration as ill be sure to check to see if one of them tunes better than the others .
Avanti AV-190 "Saturn "
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B
BOOTY MONSTER
Guest
LOL , i hear ya on the birds . im not gonna try 1/2 wave radials , was just mentioning i had seen a few comments about them . im gonna be using 9 ft radials on this project . 
experimenting is good booty, sometimes its the only way to see what works best at your location,
i would hold off on the 1/2wave or longer radials @ 27mhz,
that is an awfull lot of tube for shitting birds to perch on
I agree with your comments. The only reason I discouraged BM from trying a home brew Sigma style antenna is because he recently told me that he has health problems and wouldn't be able to get up and down on the roof repeatedly---trying to get things right.
Bob, I looked at the link that BM posted for the Saturn. In the manual on page 13 there is a discussion for making a tuned 1/2 wave line using a T-connector and a dummy load. Their procedure is a little different from the way I do the process. They say after you see a low SWR, to advance the calibration control so the meter reads mid-scale and then continue to cut as long as the needle goes lower and if it goes higher then you have cut off too much. I can see it making sense, but I have never re-calibrated the meter during the process. The last time I tried this method for making a resonant 1/2 wave line I made another step after I thought I found the lowest SWR. With the setup in the reflect mode and having reached the lowest SWR---I went up and down in frequency the entire CB bandwidth. Surprisingly I saw no change in the SWR. I was surprised this method appeared to be so broad banded. Doesn't this mean that the actual length is not so critical as we imagined? Maybe if I had followed the procedure above, I would get better results.
How say you?BM's your new idea to do your tuning and comparisons down low for the various radial setups sounds good. However, at some point I do raise my antennas up above the house to record the signals for my Signal Reports.
Another thing: I do my Marconi6 that has 3 horizontal and 3 slanted down radials for the same test strictly out of convince. One of my A99 hubs has 3 holes horizontal and 3 holes slanted down that are off-set symmetrically. I would prefer to test 6 radials horizontal and then test 6 radials slanted down, but that would require a different hub.
i agree with you on the sigma style antennas eddie, you do need time and energy to get the best from them,
the t-piece method is the way i did it years ago, when you get the reflect low wind the setpot up to see smaller changes, it seems to get you pretty close,
imho its best to get the meter/analyser direct to feedpoint for taking bandwidth measurements,
next best would be cut 3 halfwave lines for your chosen test frequencies, how critical it is depends on how accurate you want to be.
the t-piece method is the way i did it years ago, when you get the reflect low wind the setpot up to see smaller changes, it seems to get you pretty close,
imho its best to get the meter/analyser direct to feedpoint for taking bandwidth measurements,
next best would be cut 3 halfwave lines for your chosen test frequencies, how critical it is depends on how accurate you want to be.
experimenting is good booty, sometimes its the only way to see what works best at your location,
i would hold off on the 1/2wave or longer radials @ 27mhz,
that is an awfull lot of tube for shitting birds to perch on
In essence bob you just quantified what AMPOWER's been saying for years. :bdh:
So as to not leave any misunderstandings in my previous words questioning this procedure for making a tuned 1/2 wave jumper or multiples, using the dummy load and a T-connector as described in the attached image. I have reconsidered what I was seeing when I trimmed the line to the lowest SWR and then moved up and down frequency covering the entire CB bandwidth. I was wrong with the implications I left.
I stated, when moving frequency I saw no change in the SWR from channel 1 to 40. This leaves the idea the procedure was too broad banded to be useful. This test uses a dummy load that pretty much covers the entire HF bandwidth and thus is very broad banded, so why would one expect a change in frequency to show any difference on the SWR meter or analyzer by a simple change in frequency? I was wrong, you wouldn't, that is what a good dummy load does.
I do find that this test produces the same or very similar results as when you're using the math: 492 x VF / frequency = length in feet. However, when using the math you have to know the precise velocity factor and that can vary even in the same coax batch, and when using the T-connector idea the velocity factor, whatever it is, will be accounted for thru the process itself and that is an advantage.
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