was on a pallet. About 60 of these were built. This was followed in 1944 with the Tachi-18, a much lighter, further simplified version that could be carried with troops. Several hundred of these "portable" sets were built, and a number were found as the Japanese vacated distant occupied territory. All of these continued to operate in the 3- to 4-m band. Other land-based radars developed by the Imperial Army included two height-finder sets, Tachi-20 and Tachi-35, but they were too late to be put into service. There was also Tachi-28, a radar-based aircraft guidance set. The TTRI also developed the Tachi-24, their slightly modified version of the German Würzburg radar, but this was never put into production. The Imperial Army had its own ships, ranging in size from attack motorboats to large landing crafts. For these, they developed Tase-1 and Tase-2, both anti-surface radars. The Imperial Army also had its own Air Divisions with fighters, bombers, transports, and reconnaissance aircraft. Only two systems were developed for these aircraft: Taki-1, an airborne surveillance radar in three models, and Taki-11, an airborne electronic countermeasures (ECM) set. Imperial Navy The Naval Technical Research Institute (NTRI) began work on a pulse-modulated system in August 1941, even before Yoji Ito returned from Germany. With assistance from NEC (Nippon Electric Company) and the Research Laboratory of NHK (Japan Broadcasting Corporation), a prototype set was developed on a crash basis. Kenjiro Takayanagi, Chief Engineer of NHK, developed the pulse-forming and timing circuits as well as the receiver display. The prototype was tested in early September. The system, Japan's first full radar, was designated Mark 1 Model 1. (This type of designation is shortened herein to the numbers only; e.g., Type 11.) The system operated at 3.0 m (100 MHz) with a peak-power of 40 kW. Dipole arrays with mat-type reflectors were used in separate antennas for transmitting and receiving. In November 1941, the first manufactured Type 11 was placed into service as a land-based early-warning radar on the Pacific coast. A large system, it weighed close to . Some 30 sets were built and used throughout the war. The detection range was about for single aircraft and for groups. Type 12, another land-based early-warning system, followed during 1942. It was similar to its predecessor but lighter in weight (about ) and on a movable platform. Three versions were made; they operated at either 2.0 m (150