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The AN/UPN-1 was a radar Pathfinder radio beacon used by the United States Army Air Forces and Airborne forces during World War II.

Radar beacon AN/UPN-1, sometimes known as BUPS (Beacon, Ultra Portable, S-band), is an ultra-portable radio beacon for ground, paratroop or shipboard use having a range of 35 to 50 miles. The set is capable of being interrogated by airborne radars operating on beacon function and replying with a coded signal permitting the beacon to be located in range and azimuth. It is capable of transmitting five different codes, it transmits on 3256 Mc. and receives on 3333 Mc. peak power out-put is 50 Watts.


BUPS antenna.jpg
  • RT-72 Transponder assembly
  • CY-220 case
  • MX-242 harness
  • CY-221 chest
  • CY-222 battery case
  • PP-116 Rectifier battery charger
  • MX-253 harness
  • AS-172 antenna assembly
  • AS-171 antenna assembly
  • CX-237 cord
  • CG-92 cord
  • AB-49 antenna support
  • CY-225 case


  • TM 11-227 Signal Communication Directory. dated 10 April 1944
  • TM 11-487 Electrical Communication systems Equipment. dated 2 October 1944
  • Graphic Survey of Radio and Radar Equipment Used by the Army Airforce. section 3 Radio Navigation Equipment Dated May 1945