Re: Have Blue off range

Message posted by Hal on March 13, 2002 at 9:01:10 PST:

What you say is true if you want to understand the radiated field of an airborne antenna. However, if you want to examine how that antenna--in the HB case, located on the upper area of the wing--responds to various airborne radars (look down), you look at things right side up. We were transmitting various wavelengths at the site of the antenna--it's design wavelength, half that wavelength, a quarter of that wavelength, double that wavelength, etc.

The initial problem stated in the message was suspicious re-radiation (reflection) of an airborne radar on another aircraft. It was initially thought that the location of the antenna on the HB was the culprit; in retrospect the whole of the testing could have taken place on a lab bench, but the AF chose to involve the whole craft for a speedy solution. The solution was rather mundane--an error in the formulation of the dialectric coatings of the waveguide feed.

Our facility was equipped with a hangar lab--our electronic warfare lab, large enough to get a whole FA-18 inside with room to spare and a separate facility next door that was an anechoic chamber in which a fairly large aircraft could enter via hangar-like doors. The anechoic facility also had openings that allowed only the nose of various aircraft to "poke" in. The indoor anechoic facility had the movable sensor--the crane spoken of in your post. We used a small "crane" to elevate our transmit antennas.

That was an interesting log periodic antenna in your attachment--capacity "hats" on the elements. I've tried that with home made Yagi antennas for ham radio. You can calculate the upper limit of the radio frequency of the antennas being tested on the wire mesh aircraft if you have the size of the mesh.

In Reply to: Re: Have Blue off range posted by gary on March 13, 2002 at 0:28:21 PST:


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