Description
WWII U.S. Army Air Forces AN/APN-2 Rebecca Antenna Kit — AT-2A/APN-2 and AN-148-B
Item Overview
This new/old stock World War II U.S. Army Air Forces antenna kit represents the aircraft side of the Rebecca/Eureka radar-navigation system. Rebecca equipment aboard the aircraft sent interrogation signals and received replies from an Eureka beacon placed near a landing area, parachute drop zone, or supply target. The returned signals helped the aircrew determine the beacon’s direction and distance. This listing is for Rebecca aircraft antenna equipment identified with the AT-2A/APN-2 and AN-148-B designations. It is not an AN/PPN-1 Eureka ground beacon. Rebecca/Eureka equipment became closely associated with C-47 Skytrain and C-46 Commando troop-carrier operations and the pathfinder teams that guided airborne formations during World War II, but the radar system was also installed on variations of the B-17, B-24, and B-25 bombers. Check out the two interesting Rebecca/Eureka videos we have listed under the "Videos" tab above.
Identification and Features
The AT-2A/APN-2 was a braced version of the AT-2/APN-2 receiving antenna used with Radio Set AN/APN-2. It was a vertically polarized, two-element Yagi antenna consisting of a dipole and forward-pointing director inside a streamlined housing. Two receiving antennas were normally installed, with one on each side of the aircraft fuselage. The added supports on the AT-2A reduced vibration damage encountered with the earlier antenna. The AN-148-B is separately cataloged as a Rebecca/Eureka aircraft antenna and has a distinctive H-shaped assembly within a streamlined housing. AT-2A/APN-2 and AN-148-B are documented Rebecca antenna designations, but they should not be treated as two forms of the same official model number.
- Service: U.S. Army Air Forces
- System: AN/APN-2 Rebecca airborne navigation equipment
- Antenna designations: AT-2A/APN-2 and AN-148-B
- AT-2A/APN-2 type: Two-element directional Yagi
- AT-2A/APN-2 frequency range: 214–234 MHz
- Polarization: Vertical
- Primary role: Direction and range guidance from an Eureka ground beacon
- Documented mission type: Airborne troop, glider, and supply-drop navigation
Historical Background
Rebecca/Eureka began as a British wartime navigation project and was further developed and manufactured for American service. The U.S. airborne Rebecca equipment received the designation AN/APN-2, while portable Eureka beacons included the AN/PPN-1 and AN/PPN-2. The system gave troop-carrier crews a practical way to locate a small ground beacon at night or in poor visibility. American wartime production placed Rebecca/Eureka equipment into wider service as airborne forces prepared for major operations in Europe. Its compact ground equipment could be carried by pathfinder teams, set up near a planned drop zone, and activated before the main aircraft formation arrived.
How the Rebecca System Worked
The aircraft’s Rebecca set transmitted a series of interrogation pulses. When an Eureka beacon received those pulses, it sent a reply on a different frequency. The aircraft’s left and right receiving antennas picked up the return signal and sent it to the cockpit indicator. A stronger response on one side showed the pilot or navigator which way to turn toward the beacon. The time between the outgoing pulse and the returned signal provided range information. This allowed a transport aircraft to home on a ground team without relying only on visible landmarks, lights, or voice instructions.
Antenna Configuration
The standard AN/APN-2 installation used a transmitting antenna and two directional receiving antennas. Original technical illustrations show an AT-1/APN-2 transmitting antenna with one AT-2-series receiving antenna mounted on each side of the fuselage. The receiver antennas were installed with their directors facing forward so differences between the left and right signals could show the direction of the beacon. The AT-2A/APN-2 retained this basic arrangement but added two supporting braces for greater strength. The AN-148-B was another aircraft antenna cataloged for Rebecca/Eureka service and is recognized by its H-shaped antenna structure and streamlined housing.
End-Item Application
Rebecca equipment was installed aboard troop-carrier aircraft that needed to locate pathfinder beacons, drop zones, landing areas, and supply points. Its best-known American application was the Douglas C-47 Skytrain used by the U.S. Army Air Forces. The antenna equipment formed only the external part of a larger installation that also included the AN/APN-2 receiver-transmitter, cockpit control equipment, indicator, cables, and power connections. Once installed and connected, the system gave the navigator or pilot a cockpit display showing the direction and approximate range to the cooperating Eureka beacon.
Rebecca/Eureka System Background
Rebecca and Eureka were the two cooperating halves of the system. Rebecca was carried aboard the aircraft and included the transmitter, receivers, cockpit display, controls, and external antennas. Eureka was the portable ground beacon carried by pathfinder or signal personnel. A Rebecca-equipped aircraft could not obtain this guidance unless a compatible Eureka beacon was operating within reception range. This partnership allowed a small team on the ground to guide a much larger formation toward a selected area while limiting the need for visible ground signals.
C-47 Skytrain Background
The C-47 Skytrain was the military transport version of the Douglas DC-3 and became one of the principal Allied transport aircraft of World War II. It carried paratroopers, cargo, medical evacuees, and supplies, and it also towed gliders. During airborne operations, C-47 crews often flew at night and in tightly timed formations over unfamiliar territory. Rebecca/Eureka guidance helped selected aircraft locate pathfinder teams and approach planned drop or landing areas when ordinary visual navigation was difficult.
History of Use
Rebecca/Eureka supported parachute assaults, glider operations, and aerial resupply missions. Before the Normandy landings, pathfinder teams flew ahead of the main airborne formations and established Eureka beacons near selected drop zones. On the night of June 5–6, 1944, C-47 aircraft delivered American pathfinder teams to Normandy, where their beacons helped guide following troop-carrier aircraft. Wartime technical records also describe the system as useful for directing aircraft carrying supplies to isolated units and resistance forces. Results depended on the ground beacon being placed and operating correctly, but the system provided an important electronic aid when darkness, weather, or battlefield conditions hid the target area.
Condition
This listing includes the Rebecca aircraft antenna components shown in the inventory photographs. Examine the photographs for the finish, markings, mounting points, included brackets, hardware, and completeness of each component. The AN/APN-2 receiver-transmitter, cockpit indicator, control unit, aircraft wiring, and Eureka ground beacon were separate parts of the complete navigation system and are not included unless shown. This equipment is offered as a historic aircraft-navigation display and restoration component. The antenna is new/old stock, but it has been in warehouse storage for over 70 years. The unit will be shipped disassembled.......not assembled as it is shown in some of the photos.
Ideal For
This Rebecca antenna kit offers a documented connection to World War II airborne navigation, C-47 troop-carrier operations, and the pathfinder teams that guided parachute and supply missions. Its specialized shapes and wartime design make it suitable for a focused aircraft, signals, radar, or airborne-forces collection.
- C-47 Skytrain restoration displays
- World War II Army Air Forces collections
- Airborne and pathfinder exhibits
- Historic radar and navigation displays
- Military avionics research collections
Approx length 25", Approx width 14", Approx height 12", Approx weight 15 lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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