Imperial Japanese naval radar technology was commonly considered inferior compared to that of the Allied nations. This was largely the result of neglect by the
military and naval leadership and a lack of a technical base in Japan. The IJN was aware of the potential of radar but experimentation and development came later in the
game and by then was behind that of the United States and England. Inter-service rivalry further hindered advances. The Imperial Japanese Army ordered its radar
group not to divulge any of its research results to the Navy group and vice-versa. This led to duplicative efforts that were terribly inefficient. Japan was also working
in relative isolation, which further hampered efforts. The United States and England were regularly sharing research results. By the end of the war, quality control on
Japanese electronics was so poor that often only one vacuum tube in 100 passed inspection and even those had an average failure rate of about 100 hours. For a
system with 40 tubes, this meant an average time to failure of just two or three hours.
Despite of all of these obstacles, several types of ship borne radars were developed and installed on IJN ships. The Type 13 was an anti-aircraft radar that became
operational in March 1943. The Type 13 was an unusual looking set in that it was a narrow vertical frame with an array of dipoles. The Type 21 was an anti-aircraft
and surface detection radar that became operational in August 1943. This radar had a more traditional appearance and was nicknamed the “
Ship Mattress”. The Type
22 was an anti-aircraft and surface detection radar that became operational in September 1944. The Type 22 was made up of two horns that were steerable. It was
also widely used and though it was not designed for gunnery control, it was used for that purpose with moderate success.

Rainbow Model Set RB 3552, Imperial Japanese Navy radars, is comprised of photo-etch brass and resin parts. The photo-etch fret has parts to build three Type 13
and six Type 21 radars and four resin Type 22 sets. For the Type 21, you get two versions: one with a larger “mattress” and one with a smaller “mattress”. You get
four of the former and two of the latter. The smaller version appears to have been fitted on
Yamato class battleships and Agano class cruisers. The photo-etch is
well done with and gives you different options for mounting the radars to a mast or a base, including those fitted on
Yamato class and Agano class ships  This
provides flexibility to modelers but research on their part is needed to see what is correct for the ship you are building. The fret has part numbers etched into for
easy identification. The set is rounded off with four finely cast resin Type 22 radars. A small, fully illustrated guide is included which shows how to assembly the
photo-etch radars with each part referenced by its part number.
The IJN Radars set from Rainbow Model is a great little set with well-done brass and clean resin casting. This set will let you fit your Nihon Kaigun model with
detailed radars. My thanks to Rainbow Model for providing the review sample.
Felix Bustelo