Analog phase shifter
AssigneeGeneral Microwave Corporation
InventorSamuel Hopfer
Life of this patent
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Abstract
This invention relates to an analog phase shifter for radio frequency signals that employs a hybrid coupler and biased varactor diodes at its reflection terminals. The diodes are operated so that the normalized reactance is unity (equals the coupler's input impedance) at an intermediate frequency which may be the geometric mean of the end frequencies of a broad bandwidth. The couplers are cascaded in tandem for a 360.degree. phase shift. A balanced configuration of hybrid couplers is used for the phase shifter.
Claims18
An analog phase shifter for electrical signals at microwave radio frequencies within a certain broad bandwidth, said phase shifter comprising:
- a hybrid coupler having a certain input impedance and including two reflection terminals, and two signal terminals respectively for receiving radio frequency signals from a source and for supplying said signals at a desired phase shift;
- and separate similar means for producing a variable reactance connected to said reflection terminals to control the angle of signal reflectance thereat and thereby said phase shift, said variable reactance means, each producing an intermediate reactance approximately equal in magnitude to the input impedance of said coupler at an intermediate frequency of said bandwidth, and including means for varying said reactance over a certain range about said intermediate reactance in response to a control signal;
- whereby said phase shifter is substantially independent of frequency over said bandwidth of radio frequencies.
An analog phase shifter for electrical signals at radio frequencies within a certain bandwidth comprising:
- a first and a second plurality of similar variable phase shifter devices connected in tandem with the output terminal of one phase shifter device connected to the input terminal of another, each of said phase shifter devices including a similar 90.degree. hybrid coupler having an input and an output terminal and two reflection terminals, and a separate variable reactor terminating each of said reflection terminals including means for varying the reactance of said reactor in response to a control signal;
- a power splitter including a similar 90.degree. hybrid coupler for supplying said signals in balanced symmetrical relation to the input signal terminals of one of said phase shifter devices of each of said two pluralities of shifter devices;
- and a combiner including a similar 90.degree. hybrid coupler for recombining the phase-shifted signals in balanced symmetrical relation from the output signal terminal of another of said phase shifter devices of each of said two pluralities of shifter devices;
- said phase shifter devices, power splitter and combiner being connected in reciprocal relation;
- whereby spurious reflections tend to be cancelled by the balanced symmetrical relation.
An analog phase shifter for electrical signals at microwave radio frequencies within a certain broad bandwidth, said phase shifter comprising:
- a multiterminal passive device having a certain characteristic impedance, and including an input terminal for receiving microwave radio frequency signals, a reflection terminal, and an output terminal for supplying said signals at a desired phase shift determined by the reflectance at said reflection terminal;
- and means, including a variable reactance network connected to said reflection terminal to control the angle of said reflectance, for varying the phase angle of the output signals approximately as a logarithmic relation of the reactance of said network over said bandwidth, the frequency dependent portion of the reactance of said network being factorable;
- whereby said phase shifter operates substantially independently of frequency over said bandwidth of radio frequencies.
Dependencies are inferred from the claim text.