EGON Verfahren

Erstling - Gemse - Ortung und Navigation


A German technique based on I.F.F. but used as to increase radar-system-range 

Florian Eibensteiner had been very kind and managed to obtain a general manual, explaining at least what EGON is about. 


The meaning of Merblatt only implies a general information

Where only something being explained very briefly.


This technique is also known as Secondary Radar



So-called AN was based on slit-beam technology

Generally two sides of an double antenna-array being operated; where by means of a so-called "Umwegleitung" or delay-line beams being successively switched between.

Each signal being fed onto the according split-screen side.

Beaming centre is accomplished when both signals (left and right) are having equal amplitudes.

An interesting aspect, why is the signal on the right-hand side being drawn facing downwards?

Freya, as well as all other GEMA related radars, operated dual-beam CRTs.

Where the lower screen section being used for watching the signals originating from the I.F.F. (Freund-Feind-Kennung).

The upper CRT section being used for regular radar operation; but EGON didn't operate the normal radar rig.


It is clear that this apparatus is only meant for EGON operations

What isn't clearly visible, is that the antennae must have a vertical polarised array.

Whilst in the days EGON technique was adopted that Freya related gear operated horizontally polarised antenna arrays.

But why was vertical polarisation used?

Simply because the aircraft I.F.F. antenna mounted at an aircraft fuselage consisted of a simple rod antenna facing earthwards.



Ju 88S type

Please notice the white rod facing from the low side fuselage, this actually is the FuG 25a antenna, combined reception as well as transmission antenna.



The EGON apparatus rig motorised (Flum 42)

The main difference with the foregoing apparatus is technically the first one consists of two antenna section and this one, apparently, being fit with a combined array; but both types must operate vertically polarised antennae.



A Nomogram expressing the flying altitude versus optical range

Because this aspect is what limited EGON operation.


Richtlinien fuer das EGON-Jagdverfahren PDF