GB998883A - Improvements in or relating to radio direction finders - Google Patents

Abstract

998,883. Radio direction finders. TELEFUNKEN PATENTVERWERTUNGS-G.m.b.H. May 7, 1962 [May 6, 1961], No. 17455/62. Heading H4D. A radio direction finder for ascertaining the angle of elevation and the azimuth of incoming radio waves, comprises an Adcock aerial system 11 arranged to provide indication of the azimuth of incoming radio waves, a co-operating aerial mounted above the Adcock aerial system on a common vertical axis therewith, two separate receiving channels 3 and 4, means deriving a non- directional signal from said Adcock system, means for applying said non-directional signal to one of said channels 4, means for applying signals from said co-operating aerial 12 to the other of said channels 3, and means 7 responsive to the phase difference of the output of the two channels for indicating the angle of elevation. The signal from aerial 12 is passed through a receiver 3 and an amplitude limiter 5, to produce a waveform 1a The Adcock aerial system 11 as well as providing the normal azimuth indicating line 16 on a double beam C.R.T. 15 provided with a first set of orthogonal deflecting plates fed via receivers 13 and 14 respectively with the outputs of the two orthogonal aerial pairs, produces a combined non-directional signal which is amplified in unit 17 and passed through receiver 4 and limiter 6 to produce a waveform 1a<SP>1</SP>. The phase difference between the two waveforms depends on the angle of elevation of the incoming radio waves. The two waveforms are fed to a difference circuit 7 which produces the difference between the two waveforms shown at lb. This waveform is then rectified in unit 8 (waveform 1c) and integrated in unit 9 (waveform Id). The resulting waveform 1d has an amplitude proportional to the phase difference between the waveforms 1a and 1a<SP>1</SP> and thus the required elevation. The output of an oscillator 19 is fed to the second set of orthogonal deflecting plates of C.R.T. 15, one pair of plates being fed via a 90 degrees phase shifter 20, such that the second beam of the C.R.T. produces a circle 18 on the C.R.T. screen. The signals fed to the deflecting plates are varied in amplitude in means 21 and 22 in accordance with amplitude of waveform Id, such that the circle 18 has a diameter indicative of the elevation of the incoming radio-wave. Alternatively the radius of the circle can be varied by controlling the acceleration of the electron beam in dependence on the amplitude of waveform Id. In another embodiment, Fig. 2 (not shown), only two receivers may be used with a single beam C.R.T., switching means being provided to automatically switch the apparatus from azimuth to elevation display, two traces being continuously seen due to after-glow. The two limited signals (waveforms 1 and 1a<SP>1</SP> may alternatively be added in unit 7. Horizontally polarized waves can be received by using an aerial system, with four horizontally positioned frames and also a further frame in a horizontal plane, above and in the axis of the aerial system.