A new survey on the Mammut radar system


Since recently, I encountered on various occasions the existence of the naval (KM) Mammut radar system FuMO 51 - 52. Be it due to an excursion to a V 143 bunker or caused by a very nice and interesting French publication. 


Stations radar et radio-navigation

sur le Mur de l'Atlantique

Spécial Normandie d'Antifer ŕ Granville


By Alain Chazette - Bernard Paich

and others

Publiced spring 2015

When you have an opportunity buy one!

ISBN 9 782915 767254


Page being initiated on 12 June 2015


Status: 17 June 2015





Viewing the GAF (Luftwaffe) version of Mammut

FuMO 52 was the Naval (KM) designation. Also their techniques differed only slightly. The main difference being that the naval FuMO 52 did have three pylons to stand at; whereas the GAF version relied upon a 4 pylon mounting. Hence, this photo clearly shows that it concerns a Luftwaffe version.  



A survey has been started

This survey, like was done during the long lasting Nachtfee survey, I will building it up from all the bits and pieces where we have access to. This time, of course, doing it virtually, as we do not possess the hardware!

Doing it this way, might implicate errors or incorrect estimations, but this is all in the game. I would say - inevitable in such an approach. On the other hand, it becomes an intriguing process, with quite some potholes. 


Digesting Alain Chazette's wonderful book, I learned, that there existed a great difference between FuMO 51 and FuMO 52. The giant antenna system belonged to Mammut. Its predecessor concerned a smaller system. Where the antenna and equipment is derived from a Seetakt system, though having a bigger antenna arrangement.


I received on 19 June, an e-mail from Prof. Hugh Griffith in which he commented:

If you write a piece on Mammuts, you should call it 'Compulsive Hoarding'.

He is quite right - digging into such a subject is often becoming an obsession. Because, you virtually touch aspects of the past which is, for the time being, becoming a part of yourself. On the other hand, luckily, not being bothered with the danger of war, under which all took place.  Nevertheless, rather intriguing, is, that one have to judge layers where general knowledge is reaching a kind of vacuum. Even late Fritz Trenkle, whom we all owe much, is sometimes mixing up details, which comes to light when you go into it comprehensively. Being for a while just at the edge of something is very enervating and I cannot explain why, is doing something with your brains; this feeling is sensitising thoughts. Like previous were: Nachtfee, Würzburg repair project, the various joined projects together Phil Judkins, not at least this website.

Ŕ pro pos, Hoarding - was the code-name the Allies gave the Mammut installation.  Like was Chimney for the Wassermann system. We have to think of the appearance of the typical antennae constructions, not about what was kept hidden within a bunker below.         


Let us first evaluate what we possess in our archives


According the folder date where I found these photos, someone, who I cannot remember well, did send them in 2011, together with a query: Do you know what this device is? (It was Colin ?, that is what I can remember)

In some respect this photo is too nice and clean; the paint is looking too 'bright'. But I guess, for some reasons, that it might concern a range display once part of a Mammut or Wassermann system. I prefer to believe it was part of a Mammut radar site.

Please notice the mechanism on top of this photo, partly invisible.  It should be a magnifier lens, that, when pulled downwards, magnifies the displayed targets on the two CRT screens.



Viewing it from the right-hand side (It was Colin ?, that is all I can remember)

The magnifier lens on top, is showing that it really concerns a (square) lens.

When the lens-frame has been pulled down, it can be kept locked by means of the handle in front. In Gema systems like Freya as well as Seetakt, they used two lenses.

Its chassis frame is made of Al or Mg die cast; creating a ridged module.

A consideration, not yet clear to me, what kind of scopes we are looking at. Some reference* shows a dual CRT unit where the upper screen shows the entire range, whilst the lower screen is showing only a magnified sector in conjunction to the range-delay measuring system (Messkette); in casu, displaying a certain range sector.

* Referring to the book mentioned at the start of this webpage, at the top of page 12, for which we kindly got, in the meantime, permission of reproduction; and will be dealt with in due course on this webpage.

On the other hand, there is also the possibility, that it concerns that the upper CRT screen shows the range from 0 - 150 km and the lower screen the range between 150 - 300 km.



Like all GEMA related radar systems, they relied upon a PRF of 500 Hz (2 ms). Allowing a radar range of 600 / 2 = 300 km.

In almost every publication on Mammut is dealt with 200 km range. I suppose, that they consider here the effective radar coverage. Whereas, Wassermann did have ranges up to 300 km, likely because, as we will notice below, it could change elevation of its radar beam.

Another finding from these two photos, is, that the lower series of potentiometer controls being linked to one another by means of (of Bakelite like) gearing wheels. A system this way I never have encountered before. Sometimes potentiometer were linked by means of gears, but linking so many together? On the other hand it might make sense, according the red-warning-sign at the gear-wheels, these potentiometers being connected onto high tensions. The CRT types apparently used are HRP2/100/1,5A, it is thus likely, that these operate with voltages of up to about 2 kV. Quite unpleasant touching!



Please consider the range-strip in front of this CRT and compare it with the previous two pictures (we got this device from late Graham Wintbold)

Above, with some careful viewing, remains of a similar scale can be noticed.


 Let us consider now a different version of the Mammut


Mammut F is a double Mammut where two antennae being mounted back-to-back (High-Frequency War, F-SU-1109-ND)

It could 'view' towards us as well as at the rear side of this antenna arrangement. All simultaneously. It, however, might have been, that the antennae where wired such that a flight-path could be followed. When, for instance, either side would steer say to west-wards, that following an over flying aircraft was difficult to follow. Therefore my estimation, that viewing it from our virtual position, was steering the beam to the left the opposite side was doing in a opposite way.  On the other hand, some is to say, for the contrary as well. Hence, both options being plausible.   

I haven't had a chance looking in details for Freya or Seetakt equipment yet. I therefore would like to go into aspects of Wassermann techniques too. 

Still considering, that both the Mammut and Wassermann relied upon comparable techniques. Albeit, that Mammut's beam was steered horizontally, whilst Wassermann's antenna pattern was being steered vertically. The difference, is that Mammut did scan an area in the horizontal plane of about 120 degrees (+60° and - 60°); this was accomplished by a rather complex phase-shifter arrangement. Wassermann could sweep its radiation-beam up and down, also operating a variable phase-shifter. But Wassermann had to be rotated for covering a horizontal sector scan. Hence, Mammut could only provide azimuth information, whereas Wassermann (when fit with a Wellenschieber) provided both azimuth as well as elevation.



An example of three Wassermann antennae (Fritz Trenkle)

The one on the far right-hand side is most likely fit with a phase-shifter provision meant for vertical beam-steering. This is the provision discussed below.



The technique is to tilt the antenna beam electrically, so that it can create an antenna beam sweeping at will to a lower - straight ahead or higher elevation. The beam-swing can hereby maintained smoothly and continuously. The connections 'd' are to be moved (controlled) for 'beam steering' for left + right simultaneously

(Frequenz, Bnd  9 / 1955  Nr. 10 pp 351-354)

Please notice, that vertical beam steering was not available on all Wassermann radar apparatus! Neglecting the azimuth rotation of its central mast.

The switching provision down this drawing is to provide split-beam operation, where the virtual beam-centre is having a null or zero reception; sometimes also known as A/N provison. Like is done when radio bearing being taken. To determine between left or right of a signal minimum is the best way obtaining optimal results. Whereas, viewing on a meter or screen where an equilibrium might be within a maximum lobe is far less accurate. Operating this technique, the switching speed (frequency) should be chosen such that visually the picture does not 'flicker' or at least not too much.

The 'e' marked line is causing a phase delay between both antennae (left and right). Below represented by the U-shaped tube.



 The U-tube constitutes the by-passing delay line 'e' and both connectors on either side equals 'f'. The Bakelite head facing towards us is to cover the electrical connection for beam switching relay



Maybe you can imagine what is being caused

(Frequenz, Bnd  9 / 1955  Nr. 10 pp 351-354)

The virtual antenna beam being tilted upwards.

Example 'b' is visualising what happens when the phase-shifter is creating a beam-tilting upwards.



The Wassermann 'Wellenschieber'

(Frequenz, Bnd  9 / 1955  Nr. 10 pp 351-354)

The black tube below connected with the bundle of coaxial cables is a so-called combiner, because the system would like to 'see' a single cable put connection. Please remember, that the Wassermann antennae fit with vertical beam-steering used two of such controllable delay-lines systems simultaneously.

The according antenna-cables being connected onto both tube ends (left and right). Please compare for it the schematic some figures previously. Beam steering being accomplished by inserting a tuneable delay-line. Where an addition to one side causing equal deficit at the other side. When the phase-shifter (Wellenschieber) being set just in the middle, the signal-delay to either side of the phase-shifting device is equal.

Digesting all this, it is evident, that the accuracy and reproducibility of the measurements, is putting a heavy burden on the quality and workmanship of the manufacturer. Of course, the mechanical design must be extremely sound. Siemens was a company that could accomplish such a high standard product.  



Electrically, delay-lines consist of a conductor (inductance) and capacitors against ground

(Frequenz, Bnd  9 / 1955  Nr. 10 pp 351-354)

The spiral groves of the electrical line are quite good visible, and the gear-like wheel is the signal connecting device


However, all phase-arrays do suffer from a nuisance and that is 'unwanted side lobes'

An antenna pattern resulting from various elements which being adding together will always creating (causing) side-lobes. Of course, optimal antenna design can minimize these unwanted lobes, but hardly preventing for it totally. All kind of tricks being invented, like the most outside radiators being parasitic loaded by resistors and other means.

A nuisance it still remains, even in our modern days.


 In this figure it is evident, that a target being at the position of  '1' will virtually be invisible

(Frequenz, Bnd  9 / 1955  Nr. 10 pp 351-354)

When it continues its flight path towards the antenna, that it will appear on the radar screen for the second time, though, how does the system distinguish from which antenna lobe the target signal originate? This figure being used for brief explanation only.

Within the nearby antenna field, beam-forming has not yet accomplished fully.


Before going into the Mammut and related technology, I would like to share a new, quite rare device.

The GEMA slotted line ES 2

Does it make sense, continuing this chapter under the title Wanted? I don't think this is the optimal way for attracting attention.

I therefore will initiate a new webpage, which's page name is more logical.

I guess, that Mammut-Wassermann does cover this Survey well.

Therefore click at the following hyperlink:

'Compulsive Hoarding'



If there is someone having additional information or knowledge, please come forward and contact us.

Please type in what you read.

By Arthur O. Bauer