station master ground plane element length
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station master ground plane element length
i finally found some decent aluminum to make the ground planes for my station master...
i assume that there are three ground planes required... anyone know the length (1/4 wave?)
doug
i assume that there are three ground planes required... anyone know the length (1/4 wave?)
doug
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lenght
I don't know if the length is that critical (at least 1/4w+10%) as much as the angle at which they are installed.
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- was grem467
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- Tom in D.C.
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- What radios do you own?: Progreso soup can with CRT
Radials...
If the radials are at a right angle to the antenna then you probably will not have a 50 ohm resistive match. If you bend the radials downward you'll reach a point where you have a 50-ohm match.
However, I've observed that gain verticals always have really short radials, and I don't understand the theory which governs this.
You might also be able to get the data you need from a website of the manufacturer on a Google search.
However, I've observed that gain verticals always have really short radials, and I don't understand the theory which governs this.
You might also be able to get the data you need from a website of the manufacturer on a Google search.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
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My two bits worth:
I am under the impression that this is a stacked co-linear antenna, and the "radials" are intended to de-couple the antenna from the supporting structure.
Most useful for increasing isolation of antennas on a tower.
If this is to be an antenna solo on a roof or tower I don't think that it makes much difference wether they are there or not.
I am under the impression that this is a stacked co-linear antenna, and the "radials" are intended to de-couple the antenna from the supporting structure.
Most useful for increasing isolation of antennas on a tower.
If this is to be an antenna solo on a roof or tower I don't think that it makes much difference wether they are there or not.
Aloha, Bernie
thanks for the replies
this antenna is now in service on a highly populated cell site doing just fine.
i see about 1w reflected pwr at 75w forward...
so i am going to leave it alone for a looooong time.
doug
i see about 1w reflected pwr at 75w forward...
so i am going to leave it alone for a looooong time.
doug
For comparison, I have a stock, two-year-old super station-master antenna on my repeater, built for 440-450 MHz, transmitting on 444.450. It's side-mounted (maybe 5 feet off the tower), is connected with 6 feet of Cellwave 1/2 inch SuperFlex coax, has an anti-sway support holding the top, is mounted about 400 feet up on a 600 foot tall tower, and is being fed with about 550 feet of Cellwave's 7/8 hardline. I'm using N connectors throughout. With a Bird 43 wattmeter and CDI elements at the repeater end of the coax, the last readings I took showed 68 watts forward on a 100w element, and about 1/2 of the first minor division on a 5w element for reflected power. That would be less than 1/10 watt, if you can even trust the meter to be at all accurate down there. It's barely enough to move the meter pointer, but it does move.
I wasn't around when the antenna was installed, so I don't know how well it was assembled by the tower crew, but I'll accept those readings any time ! I agree with your intent to leave yours alone !
Bob M.
I wasn't around when the antenna was installed, so I don't know how well it was assembled by the tower crew, but I'll accept those readings any time ! I agree with your intent to leave yours alone !
Bob M.
The true Station Masters, the earlier ones have three straight 1/4 wave radials aprox. 1/2" below the top of the alumimum support housing. The later ones use three 1/4 radials, but at a -45 degree angle, flat side to the support tube held by a radiator hose clamp.
Made by Phelps Dodge, then Cellwave, now Radio Frequency Systems.
DB Products makes a simmular looking fiberglass antenna that does not have any radials.
Made by Phelps Dodge, then Cellwave, now Radio Frequency Systems.
DB Products makes a simmular looking fiberglass antenna that does not have any radials.