This site is located at the end of Morrison Canyon Road in Alameda County, Ca. While the site has 24 and 7 security, I don't believe the area is intended to be very secret or secure. Occasionally the site will get mentioned in the local press, but ESL provides no information on the mission of the site. The land next to the site is now owned by the East Bay Regional Park District, so the days of this site being out of the public eye are numbered.
The mystery of the upside-down wire mesh airplane has been cleared up by Vern Modeland ( http://www.runningriver.com/modeland ). There was some speculation that the wire mesh airplane was a radar target, but the more likely scenario is that the plane is used to test antennas. The wire mesh airplane acts as a ground plane, which can influence the antenna radiation pattern. The goal is to measure the radiation pattern aimed downward from the airplane. If the plane were not upside-down, then the antenna would radiate towards the ground, which would be difficult to measure as there would be reflections from the ground. By mounting the airplane upside-down, the measurements are made from above, where there is little chance of reflections.
The shape of the plane is similar to the RC-12 Guardrail, and was probably used to test the antenna radiation pattern. You can find more information on Guardrail at http://www.fas.org/irp/program/collect/guardrail.htm .
The fenced-in area on the ground towards the left of the photograph has been suspected by some to mark the top of the an underground bunker.
This antenna is the largest array on the site. Given the symmetric shape and the two feed lines, I would suspect is it circularly polarized. Note that the tower has multiple sections so that it can be cranked upwards. There is a small log periodic at the base of this antenna that is mounted so low I can only suspect it is used to receive signals from the trailer.
This is a close of up the tail of the wire mesh airplane and the large antenna array. This site is about 2000ft in elevation and often is in the fog or clouds.
This tower had a microwave dish at the top that is probably aimed towards ESL's Sunnyvale location. The dishes on the hill in the back ground look like standard telecommunications relay equipment, and are probably unrelated to ESL.
Surprisingly, there is little information on the internet regarding ESL, though it is now part of TRW. Some may remember that the ESL location in Sunnyvale was the site of a workplace mass murder event. This site has some information on that event:
http://massmurder.dyns.net/richard_farley.htm
http://www.svn.net/mikekell/farley.html
A chapter in the book "Chinese Playground: A Memoir" covers
his first hand experience of this massacre.
Not mentioned on the net is that Richard Farley surrendered to the Sunnyvale SWAT for a sandwich from Togos . Hey, damn good subs.
There was a bad made-for-TV movie about the event as well. Rather than filming on location, the movie was made in Kansas. Sunnyvale would never have all those brick buildings since it is in an earthquake zone and has very poor soil.