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Old 09-03-2008, 11:23   #31
69harley
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The RF test chamber is located in the Quantico area. If you are in the know then you know where I am referring to.

Our engineers have several tweaks to apply to this antenna. The trim capacitor being one of them.

We will try to do as many different tests as possible, however, our paid reason for being in the chamber is a different project. I am going to work this antenna in as much as possible, but we only have the test chamber for a certain amount of time.

At the very least we will measure the antenna gain, front to back ratio, and radiation lobes.
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Old 09-07-2008, 11:15   #32
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I'm currently working with a variant designed from electron's specs he gave me using the materials readily available that we have in our commo shop. Using RG213 as the radiators, it gets solid VSWR for an improvised antenna, but I'm having issues correcting the impedance. When connected directly to a PSC-5, it gets a crystal clear transmit, with light static receive.

I tried using a sleeve balun (non-radiating model constructed from a 1/4 wavelength copper tube around the cable, then electrically connected to the sleeve opposite the connector, worked for a UHF dipole) but though it improved the VSWR, it still didn't function through the cable. I'm thinking of trying a choke balun next, but stuck trying to figure out the diameter/coil length.
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Old 09-11-2008, 15:50   #33
69harley
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We had the field expediant in the test chamber for a couple of tests today. The customer is paying for other stuff, but we had some setup time in between the 'paid tests' that were able to use.

BLUF - 2.6 -2.9 db of gain over the entire UFH SATCOM range. The radiation pattern that comes off this antenna is not as focused as say a 2055 or 2040. On the chart it looks more like funnel than beam. It may be able to be fine tuned by adjusting all of the variables, but without dedicated chamber time it would be almost like finding a needle in a haystack.

Maybe someone out there has a bunch of EOY money left over and would like to buy some test chamber time?

Anyway, 2.5-2.7 db of gain on a homemade array is not bad at all.

K
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Old 09-12-2008, 04:43   #34
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Thank you for the effort to get the info on the antenna. The data you provided will be valuable to those in the field.
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Old 09-12-2008, 06:37   #35
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We had the field expediant in the test chamber for a couple of tests today. The customer is paying for other stuff, but we had some setup time in between the 'paid tests' that were able to use.

BLUF - 2.6 -2.9 db of gain over the entire UFH SATCOM range. The radiation pattern that comes off this antenna is not as focused as say a 2055 or 2040. On the chart it looks more like funnel than beam. It may be able to be fine tuned by adjusting all of the variables, but without dedicated chamber time it would be almost like finding a needle in a haystack.

Maybe someone out there has a bunch of EOY money left over and would like to buy some test chamber time?

Anyway, 2.5-2.7 db of gain on a homemade array is not bad at all.

K
is that dbi or dbd?? If it's dbi, thats only about equivelent to a 1/2 wave doublet. A doublet has 2.14 db's over isotropic.

But, hey as they say, what's the best antenna?.......the one that works!
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Old 10-21-2008, 06:12   #36
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Feedback

...been getting some good feedback on the antenna... This is an e-mail I received the other day. I've omitted the name, number and unit information.

<<Electron>>,
We tested your antenna today with excellent results. We were running data thru FTP on a DAMA channel, antenna cut to freq for the channel and had 40 – 50 RSI. Had it tilted on a ruck…was ok, had it tilted by hand and of course it worked much better since the birds on the horizon. Thought I’d share this with you, many thanks.
r/
<<Name Omitted>>

XXXXXXXXXXXX
Training Instructor, Communications
Co _, __ BN, ________ (A)
(XXX) XXX-XXXX, DSN-XXX-XXXX
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Old 10-22-2008, 06:44   #37
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Good news, one of the committee guys (SATCOM Inst.) said he was gonna build one and test it. Also the guys out at Robin Sage. Hope it works out well for them. Thanks for making it available Electron.
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Old 10-31-2008, 16:36   #38
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Satcom ant. math formula

what is the 1500 in the formula?

1500/ MHZ = L L * 12= ----inches
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Old 10-31-2008, 18:25   #39
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what is the 1500 in the formula?

1500/ MHZ = L L * 12= ----inches

Better question, who are you and why did you not comply with your registration message or the stickies before jumping into a discussion?

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Old 10-31-2008, 20:06   #40
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my bad

Hey Reaper my bad for posting on here first.
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Old 11-03-2008, 06:17   #41
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It's not 1500

The fomula is 1005 divided by the frequency in MHz, then multiplied by 12 to get the length in inches. If you divide by 1500, your antenna length will be way off and you will probably experience the standing wave phenomenon.
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Old 11-03-2008, 18:39   #42
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1005?

What is 1005 supposed to be is what I'm asking?
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Old 11-03-2008, 18:49   #43
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What is 1005 supposed to be is what I'm asking?
Young man go to the 3rd post in this thread and read it carefully. It is very simple and all the info is there.
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Old 11-03-2008, 20:49   #44
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What is 1005 supposed to be is what I'm asking?
Do you mean, what does the value 1005 (or 234 for a 1/4 wave, or 468 for a 1/2 wave antenna) represent in the equation? Where did that number come from, right?
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Old 11-04-2008, 00:22   #45
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Value 1005?

What does the value 1005 represent?
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