Radar DETECTORS

[Timotheus]

Reading an Osprey book ( https://www.amazon.com/gp/product/14728 ... UTF8&psc=1 ) and have learned something new, new knowledge for me.

Apparently Japanese had radar DETECTORS, which alerted them to the presence of American ships.

Thing is, these detectors had bigger range than the American radar (at least early radar).

I can't find anything online for these Japanese radar detectors, do you have any knowledge of them?

[BBfanboy]

Don't know anything about the Japanese detectors, but the German U-boats early in the war had a very simple radar detector with an antenna of wood and wire called the Biscay Cross. It was crude but better than nothing.

It makes sense for a detector to pick up enemy radar before the enemy gets a detection signal. Only a small part of the enemy radar signal reflects back to their detector while your ship gets a full strength signal (considering the distance).

But there were instances where Allied detectors on their radars were more sensitive than the IJN detectors and they used that to their advantage. At least one US sub detected radar signals coming from an IJN sub before either side could pick up an actual radar echo from the sub. The US sub turned off its radar to avoid the IJ sub detecting it and plotted the I-boat course and speed before submerging ahead of it and nailing it with torpedoes. In this case the US sub's detector of the weak IJN sub radar signal was better than the IJN sub detection of a much more powerful US radar signal. Frequency might have also had something to do with it - the US Sub could likely detect over a wider frequency band than the IJN sub.

[Timotheus]

Yup, I know about the GERMAN radar detectors, but this is the first time I have heard (err, read) about JAPANESE radar detectors.

Any info/links would be appreciated by this nerd.

[Korvar]

The Japanese E-27 RWR (Radar Warning Receiver) was based upon the German Metox, which was actually a French design built by the companies Grandin and Sadir. The Metox RWR was the "cross"/"diamond" looking antenna that was used on German U-boats. The plans for Metox were brought from Germany on the Japanese submarine I-30 as part of the Yanagi missions - she made it all the way to Singapore in October of '42 before hitting a British mine and sinking. Some very water logged plans were later recovered by divers. It must have been enough as the Japanese fitted their prototype E-27 receiver to both the Yukikaze and the Yamashiro as of June/July 1943, respectively - before the safe arrival of the submarine I-8 in Japan at the end of the year, which was equipped with an intact Metox system. About 800 of the E-27s had been produced by the spring '44 with around 2,500 units produced by war's end.

Unfortunately for the Japanese, around the same time that E-27s were finding their way to the fleet in numbers, the Allies had pretty much moved to centimetric radar sets which made the E-27 receivers useless. In other words, the E-27s could only detect the US Navy's "L-band"/"long-wave" CXAM and SC surface search radars, as well as, perhaps the air search SC-2 and SK radars. The SG surface search units were microwave-based units which the E-27 couldn't detect.

E-27

Became Operational: April 1944
War Status: used in war
Installed: torpedo attack boat
Purpose: ESM warning indicator
Wavelength: 75-400 cm
Peak Output: n/a
Transmitter: n/a
Receiver: UN-955
Detector: n/a
Detected: enemy radar/radio use 300 km
Weight: 40 kg
Number Built: 2500
Antennae: unknown

Source: Radar @ Combined Fleet


Edit:


Source: https://www.fischer-tropsch.org/primary ... MJ_toc.htm

[Korvar]

Some additional information/images:













Apparently the Mark 49 "racquet type" antenna shown above is what later gave the E-27 receiver equipment the ability to detect centimetric waves.

[Korvar]

Another, clearer image of a submarine mounting. I've circled my best guess of where the E-27 antenna is:

[jdsrae]

Research then led to the radar detector detector

[geofflambert]

Japanese night optics using Zeiss lenses were most impressive as evidenced at the Battle of Savo Island (and others). Allied radar advanced very quickly, though, and by the Battle of Surigao Strait radar fire control was lethal.

[Gridley380]

Its anecdotal, but there are several references to radar detection in Shinano! (Enright, 1988). The story is told from both sides, and thus provides some insight into what the detection/tracking/evasion game was like. As far as I know the book is accurate, and it is certainly a great read.

[AW1Steve]

Couple of points about "RADAR detectors" and ESM (Electronic Support Measures). The range of any RADAR detecting device is theoretically 1.5 times the range of the RADAR. The only reason it would be less than that is limitation or malfunctions in the detecting device.

A basic "RADAR detector" is the simplest device imaginable. All you need is a receiver , that can access the frequency that the RADAR transmits on. It will do one thing (and one thing alone) , and that is tell you that their is a RADAR operating within a certain range of you. If you know the discrete frequency on which the particular RADAR or RADARS that you are looking for is , then you know (or suspect) the type of RADAR that is near you , and MAYBE , just MAYBE (depending on the skill of your operator , and depending on the skill of the RADAR operator) the range , and if it's closing or going away from you. MATBE (there are a LOT of variables at play here).

You cannot get a bearing. IF you are aboard an aircraft , you have a competent operator , and a cooperative pilot , IF the RADAR has a slow , regular scan , and IF you can do a rapid 90 degree turn before you get another "cut" (that is a signal from the RADAR of interest) then you MIGHT be able to get an approximate bearing.

For a submarine using such a detector , all you suspect is that there is a RADAR searching somewhere around you. Maybe. With out a direction finding set up , Devices like the METOX get to be a real pain in the neck because you never know if it's a real warning or not. And as a good RADAR can pick up a periscope , all you can do is stay submerged. You can't charge your batteries (that means being surfaced) you can't raise your periscope and you can't search for targets , let alone attack them. From a ASW point of view ESM is very useful. From an early warning point of view for a bunch of ships , it might be useful , if some of the ships are spread out enough that you can triangulate on the point of origin. For a series of shore bases , it's a piece of cake , and very, very useful (Think of "HuffDuff" in ww2. Same principal).

[AW1Steve]

Of course in what Churchill called "The Wizard War" , nothing was static. Change the RADAR to an unsearched for frequency , and the target has no idea that he had been painted. [:D]

[Korvar]

ORIGINAL: AW1Steve

Devices like the METOX get to be a real pain in the neck because you never know if it's a real warning or not.

That's a very good point. Early radars and warning receivers were really only useful in 'quiet' areas; for example, the Japanese had decent luck with them in China because the Chinese air force was few in number and mostly lacked radiating devices of their own (radios, etc.). As long as the Japanese controlled for friendly false positives, they could be relatively certain that any returns were the Chinese.

The same would apply out in the middle of the Pacific... less so near islands/bases which tended to generate a lot of electromagnetic noise.

[spence]

Research then led to the radar detector detector

In December 1942 British codebreakers regained the ability to decipher messages encrypted with naval Enigma machines. The Germans noticed the resulting uptick in spotted U-Boats. Based on their confidence in the Enigma machine, as well as the testimony of a captured British bomber pilot, the Germans came to the erroneous conclusion that the Allies had developed a means for detecting emissions produced by the Metox itself.[4] The executive officer of U-230, Captain Herbert Werner,[5] said of Metox, "Then, on August 3 [1943], we received a message from Headquarters which had a greater impact on our lives than any since the beginning of the Allied offensive. ALL U-BOATS. ATTENTION. ALL U-BOATS. SHUT OFF METOX AT ONCE. ENEMY IS CAPABLE OF INTERCEPTING. KEEP RADIO SILENCE UNTIL FURTHER NOTICE."

The second of the two quotes is from Wiki but I remember reading about the interrogation results given by the bomber pilot and its effect on the use by the Germans of the Metox device. Apparently the bomber was shot down by a night fighter and the operator of centimeter radar device with which the bomber was equipped partial destroyed it. When Germans interrogated him the operator stated it was a device that detected emissions by the Metox itself. The Germans eventually reverse engineered the remnants of the device but not before they correlated an uptick in attacks on surfaced subs with the bomber pilots testimony and issued the message above. By the time they reversed the prohibition the US had developed an even shorter frequency radar.

[AW1Steve]

If you are wondering how the allies picked up the Metox, look up on your favorite search engine "how do RADAR detector detectors work?" . No , I didn't stutter , I'm talking out Virginia and DC cops find out you have a RADAR detector and bust you (RADAR detectors are illegal in those two jurisdictions). [:)]

[Timotheus]

Korvar, I will say this again.

You ARE a hero.

Thanks for the sources and pics. [&o]

[fcooke]

recently moved my primary addy from NJ to NY - it was a true PITA. But I was in the DMV and the young lady asked me if I ever lived in Dorchester, Boston, MA. I said yes - how do you know that? Well, it came from a 30 year old speeding ticket where my radar detector did not work for some reason, which amused the State Trooper to no end. Now, why they had that on file but could not re-register my cars in NY is a discussion that requires adult bevvies.....

[Alpha77]

The Japanese had mostly ships radar in 44 - I read some interviews from IJ officers on a navy site...they stated mostly yes they had radar at a certain point but the operators were poor / not trained enough. So they had not much faith in it. And ofc the sets were perhaps on the technical state of 1940 or so...

As for plane bases radar and MAD, the same problem as well the MAD device was very bulky and heavy and would impact the planes performance / range etc. quite a bit.

They could detect some radar waves, but not the direction it was coming from...

[AW1Steve]

The Japanese had RADAR that displayed "A" and "B" scans. It would give you a bearing but generally not a good range. And they had no height finding RADARs for air search , making intercepts very difficult. The USN had PPI displays (planned position indicators , the round display that most people are familiar with from movies) which made a HUGE difference. [:)]

Even today , MAD is not light , although it's small enough to be used in helicopters. BTW , MAD is not really a search device (except in "choke point" locations such as the straits of Gibraltar). It's more of a localization and targeting device. You get an approximate datum for the sub , then search where you think he is. After getting several "Madmen" (contacts) you can work out a vector then carry out an attack. MAD "trapping" is very rough on the crew and airplane , consequently "open ocean" MAS is not done. [:)]

[Korvar]

Some visuals help to paint the picture:

A Scope:



PPI Scope:

[Zorch]

ORIGINAL: Korvar

Some visuals help to paint the picture:

A Scope:


PPI Scope:

Mother Nature scan: