Press Corps sure didn't get an opportunity to watch TV back in their compartment -- they were only supposed to know what the DV/media handlers wanted them to know while aboard the plane!The TV thing sounded fishy to me too that's why I asked the question but the docents at Boeing claim it was for television reception by the press corps.
Never mind it's size, that only determines it's resonant frequency. The question was what type of antenna is it and the answer is a grounded unipole. Look at it as one half of a folded dipole with the far end grounded and the near end is the feed point. It presents approximately 400 ohms impedance so it requires a tuning network to bring it down to 50 ohms if that is required by the equipment. The distance from the mounting surface to the farthest point from it is just shy of one quarter wave.
Actually it's the door handle of a fancy sports car but don't tell anybody you're goofing on them.
Sorry for the delay. Turns out the "USAF Series Aircraft VC-137C Communications and Electronics Inflight Operations Manual" has been just a few feet behind this computer instead of boxed up in another room as I thought it'd be!To Hooligan,
The antenna is below wing level, behind the wing, about halfway between th back of the wing and the rear passanger door. Alan Rudge refers to a "Bull-Ring Glidepath Antenna" in his book but don't know if that has any thing to do with any of this other than that's what I would invision it to look like.
nuthin like useful aircraft manuals handie lol, where did you get those from?Sorry for the delay. Turns out the "USAF Series Aircraft VC-137C Communications and Electronics Inflight Operations Manual" has been just a few feet behind this computer instead of boxed up in another room as I thought it'd be!
Anyway, I'm looking at an antenna locations diagram, and based on the location info you provided, as other people pointed out, this would be a TV antenna, and there should be an identical one on the other side of the fuselage. It should be a few feet closer to the rear passenger door than to the trailing edge of the wing where it attaches to the fuselage.
The "Guide Slope Antenna" is located on the nose of the plane.
Note that this data is for the C-137C aircraft. Your bird was a C-137B, but some of the antenna location data is going to be identical. I think I do still have some C-137B comms-electronics manuals, so I'll check that source once i dig one up.
Ah, as for the countermeasure pods, that sort of stuff is still kinda sensitive these days, but you can tell people that they were installed circa early 1980s, and at least when it was actually supposed to be highly classified, it was just referred to as "the system." After some of the 89th Wing aircraft got them, I know NASA put them on their 747 space shuttle transportation aircraft. You might be able to check with NASA to see if their employment was/is unclassified. Aviation Week & Space Technology magazine had some minor articles about the system. Being located behind the engine nacelles gives a clue as to what sort of surface to air threat they were countermeasures for. The System was just designed for the small variety of man-portable surface to air missiles, so the system was turned off when the aircraft was above a couple thousand feet. If I recall correctly (I'll check the same manual), controls for it were at the flight engineer's station.Thanks for everyones help and comments on this one, especially Tim. I guess it is official. To my surprise, they actually are television antennas - so none of the visitors at the Boeing Air and Space Museum were misinformed. Now I have to verify the hearsay about the ECM pods mounted behind the jet engines spitting out metallic chaff through their mesh ports, but that is a picture and question for a different forum.
Best regards to all, John - K2AZ, Seattle WA