| 摘要 |
<p>733,014. Wave-guides. NATIONAL RESEARCH COUNCIL. March 12, 1953 [March 14, 1952], No. 6899/53. Class 40 (8). [Also in Group XL (c) ) ] In a dual mixer assembly comprising a local oscillator 23 feeding energy both ways along a wave-guide or other channel 15 to rectifier mixers 34, 11 respectively receiving a portion of the transmitted energy from antenna channel 1 along channel 33 for A.F.C. of the local oscillator and most of the received wave from the same (or other) channel 1 (along channel 10) for frequency changing it to the receiver intermediate frequency, susceptance means' 16 is arranged between the local oscillator input to the channel 15 and the mixer 11 producing the receiver I.F. so that most (but not all) of the incident local oscillator energy is reflected back in the opposite direction, and attenuator means 29 between the local oscillator input and the A.F.C. mixer 34 for preventing energy travelling backwards from reaching the other mixer 11. The mixers 11, 34 connect with coaxial line output connectors 13, 36 respectively. A further susceptance control device 32 may be arranged between the attenuator 29 and mixer 34 to reflect energy back to the mixer 34, and between the mixer 34 and the input to the A.F.C. channel 33 there are arranged an apertured cutoff attenuator and a longitudinally arranged resistive attenuator strip. The attenuator 29 may likewise be a longitudinal resistive strip. The susceptance devices 16, 32 may be posts adjustably screw threaded into the wave-guide to form inductive or capacitive partial short circuits and may be gripped by spring fingers on the supports. The posts are preferably arranged at corners of the waveguides whera susceptance due to the join may be produced and the post 16 is so spaced from the local oscillator input that energy reflected to the said input is in phase with the latter. Received energy reflected from the main oscillator, e.g. a magnetron (or from an anti-TR switch) is arranged to be in phase with that directly passing into the I.F. mixer channel 10, and the latter may include a TR switch 6. The channel sections 10, 15, 33 may be integrally connected and the free end of channel 33 connected to the main (antenna) channel 1, with a lead or other gasket 44 between, by clamping bars 45, 46 and a screw adjusted yoke 47. Choke and flat couplings 2, 3 terminate the mixer antenna channel 1.</p> |
