US2380981A

US2380981A - Radio scanning system

Info

Publication number: US2380981A
Application number: US550817A
Authority: US
Inventors: Raymond J Mcelhannon
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-08-23
Filing date: 1944-08-23
Publication date: 1945-08-07
Anticipated expiration: 1962-08-07

Description

Aug. 7, 1945 R. J. MCELHANNQN immo scmmme sygmu Y Filed Aug. 23, 1944" INVENTOR. 1 RAYMOND J.- M ELI-IANPDN.v

[BY I AfroRNEY Patented Aug. 7, 1945 2,380,981 RADIO some SYSTEM Raymond J. McElhannon, Flushing, N. Y. Application August 23, 1944, Serial No. 550,817

(Granted under the act oi March 3, 1883, as

amended April'30, 1928; 370 O. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention pertains to scanning systems for radio waves, for directing a radio beam to successive points of an area to be scanned. This invention finds application among others to radio pulse and echo detection systems, commonly termed radar systems.

In accordance with a novel feature of the invention scanning is efiected by purely electrical means involving no mechanical movements or change in frequency for accomplishing the scan.

The invention employs for operation the velocity modulated type of oscillator such as the Klystron.

In the annexed drawing the single flgure shows in schematic form a preferred modification of the invention.

Referring to the drawing the rectangle l encloses a velocity modulated oscillator of special construction comprising a heated cathode for emitting a stream of electrons 2, focused by a tubular focusing element 3 maintained negative with respect to the cathode, the electron stream passing thence through accelerator grid 4, maintained at a positive potential with respect to the cathode for rendering the oscillator operative. The focused electron beam passes thence between a pair of electrostatic deflecting plates 5 another as shown. The output of resonant circuit i2 is coupled to dipole 2! over a circuit 23; while the output of resonant circuit is is similarly coupled to dipole 22 over a circuit '24. I In the operation of the device, progressive deflection of the electron beam between limiting positions I, 8, by action of the deflecting plates 5 and associated oscillator 6, causes the electron beam to pass alternately through catcher-grids l4, thence in varying degree between both catcher grids l4, l5 and thence only through catcher grids l5, the entire cycle described being thus reversed. This in turn causes radio frequency energy to be radiated first only from dipole 2! to direct the transmitted radio beam in the direction 26; thence shifting to the position 21 as dipole 22 becomes increasingly energized with corresponding decreasing energization of dipole 2| ending in the other limiting direction 28 of the radio beam when only dipole 22 is energized; whereupon this cycle of operations is repeated T in reverse, and so on.

between which a source of oscillations 6 is conheated for deflecting the electron beam between limiting positions I, 8 at a desired scanning frequency. The electron beam passes thence successively between spaced grids 9, III of a buncher' circuit including a resonant circuit ll connected therebetween. Spaced from the buncher circuit are a pair of resonant catcher circuits l2, l3, the spaced grids I4 one of which are aligned respectively with the spaced grids I5 of the other. Beyond the catcher circuits is a collector plate I! maintained positive with respect to the cathode. For establishing and maintaining sustained oscillations, feed-back circuits l8, l9 couple the resonant catcher circuits l2, l3 to the buncher circuit H.

20 is a metal parabolic reflector maintained stationary and mounting elf-center a pair of dipoleradiators 2|, 22 inclined at an angle to one The circuit may be arranged for reflex Klystron operation by applying a suitable negative potential to plate I1, and omitting the buncher circuit I l and associated grids 9, Iii in which case circuits l2, l3 would operate concurrently as both "buncher" and catcher" elements.

To provide pulse type operation for pulse and echo detection, a keying circuit may be interposed4 between the cathode. i and the accelerator grid In order to minimize coupling effect between grids I l and I5, circuit l3 may be shifted longitudinally with respect to circuit ii, for example one wavelength.

I claim:

Apparatus for variably deflecting radio waves, comprising: a velocity modulated oscillator including a pair of catcher circuits, means'for producing a velocity modulated cathode beam, and means for variably deflecting said cathode beam to variably excite said catched circuits concur: rently in opposite relation, directive. antenna means energized by said catcher circuits and arranged to variably direct radiation therefrom in accordance with said variable energization of said catcher circuits.

RAYMOND J. MOELHANNON.