-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
imax2000 ground plane radial kit
- Thread starter zewac
- Start date
I think the kit comes fixed as to angle, which is slanted down some, but the angle can be changed. The length of radials are equal to the top element of the Imax or they are 72" long tips just like come with the A99 GPK.
If you are trying to build your own, I think an angle of about 35 to 45 degrees is what you will find on the kit. IMO, you will probably find that just about any length around a 1/4 wavelength for the frequency of use, shorter or longer will work just about the same, and that same is---to not make much difference at all.
I'm not sure how or if radials affect the Imax, but I would prefer that the radials on my 5/8 wave were horizontal.
Last edited:
Yeah, the IMAX radials are 72 inches long, and the angle is about 35 to 40 degrees as Marconi said.
wavelength is 36ft correct?
so 1/4 WL would be 9 feet right?
I noticed the a-99 is 1/2 WL or 18ft...
the imax is 5/8 WL or 24ft..
36/8 = 4.5
so 4.5 * 5 = 22.5ft
so would the imax actually be a little more than 5/8 WL?
WL Length
1/8 = 4.5ft
1/4 = 9ft
3/8 = 13.5ft
1/2 = 18ft
5/8 = 22.5ft
3/4 = 27ft
7/8 = 31.5ft
1 = 36ft
Also would these numbers be accurate or am I incorrect on my thinking of this?
so 1/4 WL would be 9 feet right?
I noticed the a-99 is 1/2 WL or 18ft...
the imax is 5/8 WL or 24ft..
36/8 = 4.5
so 4.5 * 5 = 22.5ft
so would the imax actually be a little more than 5/8 WL?
WL Length
1/8 = 4.5ft
1/4 = 9ft
3/8 = 13.5ft
1/2 = 18ft
5/8 = 22.5ft
3/4 = 27ft
7/8 = 31.5ft
1 = 36ft
Also would these numbers be accurate or am I incorrect on my thinking of this?
B
BOOTY MONSTER
Guest
read the imax2000 exposed again booty,
36ft is the freespace wavelength,
the radiator wire is 270.5", the matching and mounting stub make up the total length around 24ft,
freespace wavelength is often stated as 492/ frequency in mhz for a halfwave, we can't use that as the wire is not freespace it has a velocity factor,
people often use 468/ frequency for a halfwave in air, thats no good either, its not a halfwave and the wire is inside a fiberglass radome which slows the velocity of propagation even further,
a wire inside a radome / embedded in fiberglass or some other dielectric is electrically longer than the same wire in air,
ignoring end effect and ground effect, the imax with its 270.5" of radiator is physically close to other 5/8waves,
electrically it is longer than its physical length so are the aluminum antennas using fat tube,
im not going to guess how much longer in either case
36ft is the freespace wavelength,
the radiator wire is 270.5", the matching and mounting stub make up the total length around 24ft,
freespace wavelength is often stated as 492/ frequency in mhz for a halfwave, we can't use that as the wire is not freespace it has a velocity factor,
people often use 468/ frequency for a halfwave in air, thats no good either, its not a halfwave and the wire is inside a fiberglass radome which slows the velocity of propagation even further,
a wire inside a radome / embedded in fiberglass or some other dielectric is electrically longer than the same wire in air,
ignoring end effect and ground effect, the imax with its 270.5" of radiator is physically close to other 5/8waves,
electrically it is longer than its physical length so are the aluminum antennas using fat tube,
im not going to guess how much longer in either case
Thanks everyone, my station was very excellent good results.my staıtıons parts presıdent lincoln cb radıo,imax2000 antenna,rg58 coax,alinco dm130 power supply,zetagı b300p amp,zetagı hp1000 swr watt meter and matchbox.swr 26mhz 1.3/ 27mhz 1.1/ 28mhz 1.1/ 29mhz 1.2/ 30mhz 1.2
B
BOOTY MONSTER
Guest
My Imax 2000 with the GPK Ground Radials.
75' LMR-400UF ( ultra Flex )
Feed point is 18' 6"
Top is 42' 6"
I wanted to be able to easily service or remove it....just by standing on my roof.
Over all I think it tuned up " fairly " well and covers the area I use.
26.815....1.7
CB 1....1.6
CB 20....1.4
CB 40....1.2
27.515....1.2
Center Point....27.658....1.1
28.500....1.5
What do you think ?
75' LMR-400UF ( ultra Flex )
Feed point is 18' 6"
Top is 42' 6"
I wanted to be able to easily service or remove it....just by standing on my roof.
Over all I think it tuned up " fairly " well and covers the area I use.
26.815....1.7
CB 1....1.6
CB 20....1.4
CB 40....1.2
27.515....1.2
Center Point....27.658....1.1
28.500....1.5
What do you think ?
Here is an image showing the Imax circuit. The dimensional arrow represents the length of 270.5" that Tech 833 refers to as .64 wavelength in his report. This is his image and he claims the wavelength of the antenna was determined by his network analyzer---not by some formula we might use. Somebody that knows the functions of a network analyzer could address whether this is possible or not.
You guys showing the math, it looks like a 5/8 wave to me, but Bob is probably right, the small wire size used has something to do with the specific length and how it all applies to the ultimate wavelength of this antenna. So, it might be that 833's claim is also correct. I don't know for sure, but I have argued the issue with 833 and others. If 833 is right, then I ask---wouldn't the same apply to the A99?
If so, what do we say the A99 is, a 1/2 wave +?
BM, my measurements show my Imax is overall 284.5" long physically. I've heard rumors that the length was shortened some time back, so your antenna may measure different overall. If we minus out the 270.5" that 833 shows is the actual radiator, that leaves 14" and that is about the length of the bottom tuning section including the coax up to the point he shows in the image.
FYI, there is another report on the Internet that discusses why the Imax/A99 use wire instead of larger tubing. Sorry I don't recall the link. Using wire would seem to be detrimental to having a nice broad banded antenna, but we know that both the Imax and the A99 are very broad banded.
Source for some info on the A99 matcher that you might consider. This is a new version of an old report. AA5TB - The End Fed Half Wave Antenna
Some of the big time critics of these antennas, would have us believe that the inventor of the A99/Imax was looking in his junk box one day for some wire. He found a mess that was all twisted and turned in such a way as to look like it may fit on the bottom of his new Whatchamacallit antenna. He tried it and it worked. Others claim that Solarcon call this one the A99 because they tried to get their "A" model to work 98 times before success. Guess what that means for poor guy working on the Imax idea. I think Shockwave was right about the Imax taking a long time to develop.
You guys showing the math, it looks like a 5/8 wave to me, but Bob is probably right, the small wire size used has something to do with the specific length and how it all applies to the ultimate wavelength of this antenna. So, it might be that 833's claim is also correct. I don't know for sure, but I have argued the issue with 833 and others. If 833 is right, then I ask---wouldn't the same apply to the A99?
If so, what do we say the A99 is, a 1/2 wave +?
BM, my measurements show my Imax is overall 284.5" long physically. I've heard rumors that the length was shortened some time back, so your antenna may measure different overall. If we minus out the 270.5" that 833 shows is the actual radiator, that leaves 14" and that is about the length of the bottom tuning section including the coax up to the point he shows in the image.
FYI, there is another report on the Internet that discusses why the Imax/A99 use wire instead of larger tubing. Sorry I don't recall the link. Using wire would seem to be detrimental to having a nice broad banded antenna, but we know that both the Imax and the A99 are very broad banded.
Source for some info on the A99 matcher that you might consider. This is a new version of an old report. AA5TB - The End Fed Half Wave Antenna
Some of the big time critics of these antennas, would have us believe that the inventor of the A99/Imax was looking in his junk box one day for some wire. He found a mess that was all twisted and turned in such a way as to look like it may fit on the bottom of his new Whatchamacallit antenna. He tried it and it worked.
Others claim that Solarcon call this one the A99 because they tried to get their "A" model to work 98 times before success. Guess what that means for poor guy working on the Imax idea. I think Shockwave was right about the Imax taking a long time to develop.BM you could have said, that you were just checking on us to see if we were paying attention.
B
BOOTY MONSTER
Guest
im good guys . i somehow missed "I measured the copper wire elements after they were removed from their fiberglass radomes:" and was just looking at the three measured lengths he mentioned .
dear friends, 5.5m coax rg58 10cm in diameter was wrapped in plastic pipes and transmission lines hooked up. SWR Are positive impact on the setting?