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Artifact: is it an antenna?

 
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ctgivan
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Joined: 18 Sep 2017
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Location: Hutchinson, KS

PostPosted: Mon Sep 18, 2017 4:47 pm    Post subject: Artifact: is it an antenna? Reply with quote

I've been conducting research on some aspects of the Redstone missile and discovered that this component only appears on a single preserved missile:


Worse, that picture is from a source generally accepted as authoritative (www.heroicrelics.org) and he notes that he cannot identify the component. An inquiry to Jim Ryan, who was in a field artillery unit equipped with the missiles and runs www.myarmyredstonedays.com resulted in his confirming he'd never seen the piece on a tactical missile in the field.

I believe I've identified the piece in historical photos of launches that were tests and carried instrumentation the tactical missiles would not have, which makes me suspect it is related to telemetry or instrumentation. Thus, my question is: could this component be an antenna for relaying telemetry?

Another view:


Wire (with the blue wrap) and connector inside the missile:


Wire and terminating connector (loose in this display), on the left-hand side of the picture and tucked underneath the brass bracket:


This example is located at the Kansas Cosmosphere (www.cosmo.org) and these photos are from Heroic Relics.

I welcome all theories and ideas—thanks in advance for any help you can offer!
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admin
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Joined: 03 Jan 2007
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PostPosted: Mon Sep 18, 2017 6:17 pm    Post subject: Reply with quote

That does look like an IFA or PIFA antenna, modified for some reason (additional bandwidth? lower operating frequency?) From the size, I'd estimate somewhere in the 75-300Mhz region.

The back side cable does look like a coaxial cable that would be needed to feed the antenna (connect to whatever radio or sensor it is attached to).

Very cool post! Let me know if you want any more information
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ctgivan
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Joined: 18 Sep 2017
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Location: Hutchinson, KS

PostPosted: Tue Sep 19, 2017 2:38 am    Post subject: Reply with quote

Thanks for the answer!

An additional photo I took today to show the size a little better (if that changes your estimate on the MHz let me know and I'll refine my searching):


And you're right about the co-axial connection:


Once again, thank you. I assumed the rocket would require robust antennas given it's indicated temperatures reached 1000F on reentry and that a sheath of plasma typically forms around orbital class vehicles on reentry, but was unsure if this were still plausibly an antenna with such heavy construction.
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admin
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PostPosted: Tue Sep 19, 2017 9:25 pm    Post subject: Reply with quote

Yeah that is a PIFA antenna [http://www.antenna-theory.com/antennas/patches/pifa.php]

Basically, the lowest frequency of operation is about a quarter wavelength for the length of the arm. The arm there looks to be about 10 inches (0.254 meters), so I'm estimated the low frequency is about 1 meter wavelength or 300 MHz. They have an odd slot cut into the arm, I'm not sure if that is to increase the bandwidth around 300 MHz or to add some bandwidth at higher frequencies.

The coaxial cable looks to be a standard N-type RF connector, very common in antenna measurements.
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