Transmission and reception of Centimeter

Radio Waves

Progress in the field of electronic oscillations - Description of transmitting and receiving equipment - Transmitter modulation - Operation and results - Uses and applications

By Chester W. Rice

Engineering General Department, General Electric Company

General Electronic Review No. 8 August 1936


I first dealt with Chester W. Rice's techniques in my paper of 2004, on some hardly noticed radar like aspects during the inter-war period (1919 - 1939) Radar II


Incorporating also some striking techniques on behalf of General Electric Company Schenectady, New York


Their experiments, which finally led to pre-war patent claims, were granted in the main western industrialised countries. GE's experiments were commenced with a system operating at 6.25 GHz or λ = 4.8 cm.


What they did was operating a water-cooled magnetron of the so-called Hull type (also known as null-slit type). The receiver- as well as the transmitter directional antennae were each mounted inside the focus of search-light-mirrors.

A novelty might have been the practical application of Barkhausen-Kurz,valves also known as B-K valves, in the receiver front-end. This was a triode were the anode was kept at a lower voltage level than the grid system. Causing a reflection of the electrons at  the anode (actually just in front) towards the valve-grid-system again. When grid-anode distance being in a favourite relation to a selective frequency (tuning, such as a Lecher-line), the B-K valve starts generating oscillations. This principle was later adopted in the so-called reflex-klystrons too. The disadvantage of such a B-K arrangement, is, that the valve grid (always a triode) becomes the power generating source; hence, dissipating part of the valve. Generally speaking, limiting its maximum power output up to, say, 20 watt.

However, they used, like was also dealt with in Hollmann's Bnd 1 book, with B-K pre-amplifiers in the front-end section of the system; which was mounted just within the focus of the receiver-mirror.

An impression of such tube, do provide the (GE's) patent claims on such B-K devices, worded in US2156016 and US2156017. Both on behalf of Garret A. Hobart, claimed (application date) on 29 January 1936; in my perception, this is the date to work with, as the date of its granting might be officially in times where the invention claim is entirely obsolete! Legally, when a patent once is granted, an invention is being protected from that very moment of its application. Therefore in France, at the first page of a patent, you could also find the exact moment, 'up to the minute', of its handing over at the patent desk.



Imagine that the space around 22 - 23 - 24 being placed just within the focus of a parabolic mirror. The anode voltage always being kept at a lower potential than is having the valve grid.



Their apparatus was designed for measuring distance*, though, could also measure Doppler modulated signals. This latter aspect is being dealt with, where they measured speed of a vehicle at a distance of about 2 km (real-time).

* Distance was read-off by means of moving-coil meters and not from a CRT screen. They used even a rotating CRT system, but did use it in a complete different manner; as is shown somewhere below.


The Doppler speed measuring aspect was dealt with in a German article by Hans Awender in FTM Heft 11 November 1937 . For obvious reasons, they left out the aspect of measuring (detecting) conducting objects at distance. Which aspect, was very briefly dealt with in Hollman's book Bnd 2 book pages 160-161 (not equal to the PDF page numbering).


Rice and his team did solve technical problems rather clever! For instance: when Doppler modulation is involved one need signal coherence. At 6.25 GHz, in 1936? Yes, they solved this task in a most elegant way!



Right of the huge magnetron magnet we notice a pulse-modulator.

As to get it in PDF please click at the drawing above


What they actually did, was picking up some energy from the transmission beam; which thereafter was deflected by the (45°) mirrors 32 - 33 and radiated into the receiver parabolic system; albeit, rather offset centre.

Consider also the drawing reproduced in the German patent application to DE754838 below.

 As to adapt to appropriate signal levels, they implemented a grid-disk (acting as a polarisation-filter) which can be rotated in the horizontal plane (the SHF signal passed vertically). It is evident, that by this means it is possible to 'dose' the amount of transferred transmitter energy into the receiver system; Voi là a smart solution, isn't it?



The permanent magnet is quite big, according the line drawing on the first paper-page is just over 12 inch (> 30.48 cm). The circular device down right of the mirror-housing, did pick up some of the transmitter energy, and was used as to proof that energy being radiated; it also allowed controlling fine-tuning of the transmission system 

As we have noticed previously, the antenna housing (shown above the magnet) was derived from a 60 cm searchlight, thus its outside diameter will not differ much from that value.

The magnetron necessitated water cooling, because its efficiency was quite poor. It might also being caused by the application of the Doppler mode, where they had to cope with continuous waves. We must, nevertheless, count with an power output of about 10 to 20 watt; maybe a bit more.




Figure 5 is constituting a kind of PPI, but not indicating range or distance, but azimuth only, though, was meant for providing the shape of a detected object, as the concerned λ = 4.8 cm which value is small versus the size of a ship, clouds or that like. Please notice also, the provision of sector scanning

As to get it in PDF please click at the drawing above  


However, I doubt, that many in those days might have considered these latter (radar like) aspects; even not in Britain, as they, in those days, just experimented with wave-lengths of, say, 60 metres (5 MHz) or that like.


This patent was also granted in Germany, which got DE754838 on behalf of AEG, this company had strong links with GE. In the 1920s, GE owned for some time even 40% of AEG. By the way, the lingual meaning of GE Co. is equal to AEG! Both, Edison and Emil Rathenau, the founder of AEG, were good friends.



   The drawing which was accompanied to the German patent application DE754838

As to get it in PDF please click at the drawing above


It is evident, that some claims have been skipped as not to breach German law and/or policy.

The AEG changed the numbering of the essential parts involved. Maybe, because the numbering sequence should not having gaps.



The foregoing applications do not necessarily implicate that all means have then existed. In patent claims one uses as much as imagination possible; as to foresee what might become relevant and should be covered within patent claims; as to back-off competitors.


Enjoy reading this unique paper!

Transmission and reception of Centimeter

Radio Waves

By Chester W. Rice

General Electric Review No. 8 August 1936



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