ANTENNA UNIT WITH PHASE-SHIFTING MODULATOR, AND RELATED ANTENNA, SUBSYSTEM, SYSTEM, AND METHOD
In an embodiment, an antenna unit includes a coupler, a phase-shifting modulator, and an antenna element. The coupler has first and second input-output ports, a coupled port, and an isolated port. The phase-shifting modulator includes a transmission medium coupled to the coupled port, a reflector, control nodes, and active devices each having a respective first device port coupled to a respective location of the transmission medium, a respective second device port coupled to the reflector, and a respective control port coupled to a respective one of the control nodes. And the antenna element is coupled to the phase-shifting modulator via the isolated port.
1 . An antenna unit, comprising:
a coupler having first and second input-output ports, a first coupled port, and a first isolated port;
a first phase-shifting modulator including
a transmission medium coupled to the first coupled port,
a reflector,
control nodes, and
active devices each having a respective first device port coupled to a respective location of the transmission medium, a respective second device port coupled to the reflector, and a respective control port coupled to a respective one of the control nodes; and
a first antenna element coupled to the first phase-shifting modulator via the first isolated port.
2 . The antenna unit of claim 1 wherein the coupler is disposed in a layer of an antenna.
3 . The antenna unit of claim 1 wherein:
the first phase-shifting modulator is disposed in a layer of an antenna; and
the first antenna element is disposed in another layer of the antenna.
4 . The antenna unit of claim 1 wherein the first phase-shifting modulator includes a reflective reactance modulator.
5 . The antenna unit of claim 1 wherein the first antenna element includes an approximately planar conductor.
6 . The antenna unit of claim 1 , further comprising:
wherein the coupler has a second coupled port;
a second phase-shifting modulator coupled to the second coupled port; and
a second antenna element coupled to the second phase-shifting modulator.
7 . The antenna unit of claim 6 wherein the second phase-shifting modulator includes an input port coupled to the second coupled port and includes an output port coupled to the second antenna.
8 . The antenna unit of claim 6 wherein:
the coupler includes a second isolated port; and
the second antenna element is coupled to the second phase-shifting modulator via the second isolated port.
9 . The antenna unit of claim 6 wherein the second antenna element is offset from the first antenna element in a dimension along which the first and second input-output ports lie.
10 . The antenna unit of claim 6 wherein the second phase-shifting modulator includes a reflective reactance modulator.
11 . The antenna unit of claim 6 wherein the second antenna element includes an approximately planar conductor.
12 . The antenna unit of claim 1 wherein the first antenna element has an approximately square shape.
13 . The antenna unit of claim 1 wherein one of the input-output ports of the coupler is configured for coupling to a transceiver.
14 . The antenna unit of claim 1 wherein one of the input-output ports of the coupler is configured for coupling to a terminator.
15 . The antenna unit of claim 1 wherein the first phase-sifting modulator further comprises impedance networks each coupled between a respective active device and the reflector.
16 . An antenna, comprising:
control nodes; and
an array of antenna units each including
a respective coupler having first and second input-output ports, a coupled port, and an isolated port,
a respective phase-shifting modulator including
a transmission medium coupled to the first coupled port,
a reflector, and
active devices each having a respective first device port coupled to a respective location of the transmission medium, a respective second device port coupled to the reflector, and a respective control port coupled to a respective one of the control nodes; and
a respective antenna element coupled to the respective phase-shifting modulator via the isolated port.
17 . The antenna of claim 16 wherein the antenna element of one antenna unit is spaced from an antenna element of another antenna unit at least by a distance approximately equal to one half of a free-space wavelength of a signal that the antenna units are configured to receive.
18 . The antenna of claim 16 wherein the antenna element of one antenna unit is spaced from an antenna element of another antenna unit at least by a distance that is less than one half of a wavelength of a free-space wavelength of a signal that the antenna units are configured to receive.
19 . The antenna of claim 16 wherein an input-output port of a coupler of a first one of the antenna units is coupled to an input-output port of a coupler of a second antenna unit.
20 . A radar subsystem, comprising:
an antenna, including:
control nodes;
an array of antenna units each including
a respective coupler having first and second input-output ports, a coupled port, and an isolated port,
a respective phase-shifting modulator including
a transmission medium coupled to the coupled port,
a reflector, and
active devices each having a respective first device port coupled to a respective location of the transmission medium, a respective second device port coupled to the reflector, and a respective control port coupled to a respective one of the control nodes; and
a respective antenna element coupled to the respective phase-shifting modulator via the isolated port;
a transceiver circuit configured to generate, and to provide to the antenna, a transmit reference wave, and to receive, from the antenna, a receive reference wave;
a beam-steering controller circuit configured to generate, on the control nodes, respective control signals to cause the antenna
to generate, with each respective antenna element, a respective transmit signal in response to the at transmit reference wave,
to form, from the transmit signals, a transmit beam pattern including a main transmit beam,
to steer the main transmit beam,
to receive, with each respective antenna element, a respective receive signal,
to form, from the receive signals, a receive beam pattern including a main receive beam,
to steer the main receive beam, and
to generate, in response to the main receive beam, the receive reference wave; and
a master controller circuit configured to detect, in response to the receive reference wave from the transceiver circuit, an object.