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Although work on the Rad Lab's Eagle radar had preceded work on H2X, Eagle did not reach operational status until long after H2X was in production. Eagle was a remarkable invention, but it was a new approach and took major effort to get to work.

Luis Alvarez came up the idea for Eagle after a chat with Taffy Bowen in November 1941 on the need for accurate targeting radars. Alvarez wanted to build a 6 meter (20 foot) long linear array of 250 transmitting dipole antennas into the leading edge of the wing of an aircraft. If the antennas were properly arranged and controlled, their emissions would interfere with each other and focus the radar beam into a tall and narrow swath, ideal for targeting. Interference effects could also be used to electronically steer the beam over an angle of 60 degrees in front of the aircraft.

The Rad Lab environment was open to new ideas, and the energetic Alvarez quickly got the project moving. At first, the design team called it "EHIB (Every House In Berlin)", but at Lee DuBridge's insistence in early 1942 it was renamed "Eagle".

Eagle was eventually redefined as a winglike antenna that was carried below the bomber, operating in the X-band at 3 cm / 10 GHz. The antenna was to be linked up to the Norden bombsight, though it was designed to be easily connected to other bombsights as well.

Alvarez had originally envisioned the array as a waveguide, a hollow pipe with a square cross section through which microwave energy could flow, with slots cut into it at intervals to act as transmitting antennas. In practice, an array of dipole antennas was used instead, but initial tests showed that such an array didn't produce a neat forward beam. It also generated "side lobes", beams that went off at unwanted angles, wasting transmitter energy. Alvarez thought the matter over for a while, and came up with a new array design that featured twice the number of dipoles with half the spacing, with the dipoles alternating in polarity. This "reversed dipole" scheme cancelled out the side lobes.

Although there was considerable skepticism at the Rad Lab about Eagle and the project was given low priority, a prototype was successfully flight-tested on 16 June 1943.

While the Rad Lab worked on Eagle, they also used the ideas embodied in it to develop an improved early-warning radar. Longwave early-warning radars had poor resolution and poor coverage of low altitudes, allowing aerial intruders to slip in "under the radar". They were also very poor at tracking large numbers of targets.

The Rad Lab's Morton Kammer went to Britain in January 1942, only weeks after Pearl Harbor, to study the British early-warning system. Kammer hoped to get clues on how an American coastal defense system might be implemented. When he returned to the US, he spoke with Luis Alvarez, who had very helpful suggestions on how a microwave early warning radar system might be implemented, based on Eagle technology.

Kammer was assigned to the project to develop a "microwave early warning (MEW)" radar in June 1942, and the first operational MEW or "AN/CPS-1" was in operation in Britain by January 1944. Six preproduction MEWs were put together by hand at the Rad Lab to get the device out in the field.

Although Eagle and MEW were derived from similar concepts, they had little resemblance. A complete MEW system weighed about 60 tonnes (66 tonnes), required eight trucks for transport, and drew 23 kilowatts of power from a portable generator. It took 150 troops three days to pick up and move a MEW.

The MEW control electronics included five 30 centimeter (1 foot) scope displays, allowing operators to track large numbers of targets. While Eagle used electronic steering, MEW required 360-degree coverage, and so it used a rotating antenna. The MEW antenna was actually two antennas joined back-to-back, with one antenna covering low altitudes and the other covering high. Each of the two antenna consisted of a linear array with 106 dipoles in front of a solid reflector, in the form of a section of cylinder with parabolic curvature laid horizontally.

Each reflector was 7.6 meters (25 feet) wide. The low-coverage reflector was 2.4 meters (7 feet 10 inches) tall, while the high-coverage reflector was 1.5 meters (4 feet 11 inches) tall. They could form a beam only 0.8 degrees wide that could provide extremely precise location of intruders, at least in the horizontal plane. The beam was very tall and so MEW did not do well at height-finding.

A second MEW was was operational in Britain by the summer of 1944. The two radars were very useful in helping to deal with the V-1 Blitz, as MEW's longer range gave greater advance warning of flying bombs, allowing more effective fighter interceptions. Since the V-1s flew at preset low altitudes, MEW's inability to compute heights was not a problem.

The Rad Lab's office at the TRE modified a MEW system to be transportable during April 1944, and this MEW was set up on the Normandy beachhead, arriving in pieces on 12 June 1944. It included a complete fighter-control center, organized around a vertical transparent plotting panel on which plotters marked positions and wrote notes in mirror writing. The MEW helped Allied fighters protect the invasion forces from German intruders, and in particular keep track of the massive flow of air traffic over the area.

The height-finding problems was addressed by adding a British AMES Type 13 CMH radar. The same idea was used with some other MEW installations with the US counterpart to the AMES Type 13 CMH, the AN/APS-10 Little Abner.

Another MEW arrived in France in late summer, but the MEW systems were large and complicated and so were of limited use during the rapid Allied advance west. SCR-584s were more portable and accompanied the armies as they advanced.

A MEW was sent to Saipan, where the USAAF was ramping up Boeing B-29 Superfortress bomber raids against Japan. The system arrived on 21 September 1944, and was not greeted with much enthusiasm. It was big, it was clumsy, and since air traffic in the Pacific was much less dense than in Europe, longwave radars like the SCR-270s seemed able to do the job just fine. Destructive Japanese low-level intruder air raids on Saipan suggested that the longwave radars didn't do the job as well as might be desired, and the MEW was operating on top of Mount Tapochau on Saipan by New Year's Eve. Japanese raiders suddenly lost the element of surprise, and the MEW also served well to locate downed aircraft in the sea around the island.

An operational prototype of the Eagle was first flight-tested on 16 May 1944. It had a beam width of 0.4 degrees, giving it much improved accuracy relative to H2X. The radar was almost everything hoped for, its narrow beam allowing it to pick out a single large building in a city. It had a range of 260 kilometers (160 miles). Eagle never did see action in Europe, but the "AN/APQ-7", as it was formally designated, was in operation against Japan with B-29 Superfortresses by June 1945. 

The major drawback of Eagle was that it was hard to use, and postwar analysis showed that even Eagle hadn't accuracy comparable to that of optical bombsights. However, it allowed Allied bombers to attack in darkness in cloudy weather, and after the war radar bombing would become much more accurate.