Phase-selectable antenna unit and related antenna, subsystem, system, and method
In an embodiment, an antenna unit for an antenna array allows shifting the phase of a radiated or received signal without the need for a phase shifter, and includes an antenna element, switching devices, and signal couplers. The antenna element includes at least one section and signal ports each electrically isolated from each other and from each of the at least one section. The switching devices are each configured to couple a respective one of the signal ports to one of the at least one section in response to a respective control signal, and the signal couplers are each configured to couple a respective one of the signal ports to a respective location of a respective transmission medium.
1. An antenna unit, comprising:
an antenna element including at least one section and signal ports each electrically isolated from each other and from each of the at least one section;
electronic devices each configured to couple a respective one of the signal ports to a respective excitation point of one of the at least one section in response to a respective control signal; and
couplers each configured to couple a respective one of the signal ports to a respective location of a respective transmission medium.
2. The antenna unit of claim 1 wherein each of the at least one section of the antenna element includes a respective, approximately planar, two-dimensional conductor.
3. The antenna unit of claim 1 wherein each of at least one of the devices includes a respective diode.
4. The antenna unit of claim 1 wherein each of at least one of the devices includes a respective varactor.
5. The antenna unit of claim 1 wherein each of at least one of the couplers includes:
a respective opening in a member configured to be a boundary of the respective transmission medium, the respective opening configured to be at approximately a respective one of the locations of the respective transmission medium; and
a respective probe having a first end coupled to a respective one of the signal ports and having a second end coupled to the respective opening.
6. The antenna unit of claim 1 wherein each of at least one of the couplers includes:
a respective opening in a member configured to be a boundary of the respective transmission medium, the respective opening configured to be at approximately a respective one of the locations of the respective transmission medium; and
a respective probe having a first end capacitively coupled to a respective one of the signal ports and having a second end coupled to the respective opening.
7. The antenna unit of claim 1 wherein each of at least one of the couplers includes:
a respective opening in a member configured to be a boundary of the respective transmission medium, the respective opening configured to be at approximately a respective one of the locations of the respective transmission medium; and
a respective probe having a first end coupled to a respective one of the signal ports and having a second end that is configured to extend into the respective transmission medium through the respective opening.
8. The antenna unit of claim 1 wherein each of at least one of the couplers includes:
a respective opening in a first member configured to be a boundary of the respective transmission medium, the respective opening configured to be at approximately a respective one of the locations of the respective transmission medium; and
a respective probe having a first end coupled to a respective one of the signal ports and having a second end that is configured to extend through the respective opening, into the respective transmission medium, and into another opening in a second member configured to be another boundary of the respective transmission medium.
9. The antenna unit of claim 1 wherein each of at least one of the couplers includes:
a respective opening in a member configured to be a boundary of the respective transmission medium, the respective opening configured to be at approximately a respective one of the locations of the respective transmission medium; and
a respective probe having a first end coupled to a respective one of the signal ports and having a second end that extends through the respective opening.
10. The antenna unit of claim 1 wherein the antenna element is disposed over the couplers.
11. The antenna unit of claim 1 , further comprising a phase tuner configured to alter a phase of a signal at one of the antenna element and one of the respective locations of the respective transmission medium relative to a phase of a signal at the other of the antenna element and the one of the respective locations.
12. An antenna, comprising:
at least one transmission medium;
control nodes; and
an array of antenna units each including
a respective antenna element having at least one section and signal ports each electrically isolated from each other and from each of the at least one section,
respective electronic devices each coupled to a respective one of the control nodes and each configured to couple, selectively, a respective one of the signal ports to a respective excitation point of one of the at least one section, and
couplers each configured to couple a respective one of the signal ports to a respective location of a respective one of the at least one transmission medium.
13. The antenna of claim 12 wherein at least one of the at least one transmission medium includes a waveguide.
14. The antenna of claim 12 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 wavelength of a wave that at least one of the at least one transmission medium is configured to carry.
15. The antenna of claim 12 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 wave that at least one of the at least one transmission medium is configured to carry.
16. The antenna of claim 12 wherein:
at least one of the at least one transmission medium includes a respective transmission-medium signal port; and
at least one component of an antenna unit associated with the at least one of the at least one transmission medium has a respective parameter that is dependent on a distance of the antenna unit from the respective transmission-medium signal port.
17. The antenna of claim 12 , further comprising:
at least two transmission media;
wherein each of at least one coupler of at least one antenna unit is configured to couple a respective one of the signal ports to a respective location of a first one of the at least two transmission media; and
wherein each of at least another coupler of the at least one antenna unit is configured to couple a respective other of the signal ports to a respective location of a second one of the at least two transmission media.
18. An antenna, comprising:
at least one transmission medium;
control nodes; and
an array of antenna units each including
an antenna element including sections;
electronic devices each coupled to a respective one of the control nodes and each configured to enable a respective one of the sections; and
couplers each configured to couple a respective one of the sections to a respective location of a respective one of the at least one transmission medium.
19. A radar subsystem, comprising:
an antenna, including
at least one transmission medium each configured to carry a respective transmit reference wave and a respective receive transmit wave,
control nodes, and
an array of antenna units each including
an antenna element including sections;
electronic devices each coupled to a respective one of the control nodes and each configured to enable a respective one of the sections; and
couplers each configured to couple a respective one of the sections to a respective location of a respective one of the at least one transmission medium;
a transceiver circuit configured to generate each transmit reference wave and to receive each receive reference wave;
a beam-steering controller circuit configured to generate, on the control nodes, respective control signals to cause the antenna
to form, from the at least one transmission reference wave, the transmit signals,
to form, from the transmit signals, a transmit beam pattern including at least one main transmit beam,
to steer each of the at least one main transmit beam,
to form, from the receive signals, a receive beam pattern including at least one main receive beam,
to steer each of the at least one main receive beam, and
to generate, in response to the at least one main receive beam, the at least one receive reference wave; and
a master controller circuit configured to detect, in response to the at least one receive reference wave from the transceiver circuit, an object.
20. A method, comprising:
generating, in response to a reference wave, intermediate signals each having a different phase;
coupling one of the intermediate signals to a respective excitation point of the antenna element via a respective conductive probe; and
radiating a transmit signal from the antenna element in response to the one of the intermediate signals.
21. The method of claim 20 wherein generating the intermediate signals includes tapping the reference wave at respective locations of a transmission medium along which the reference wave is propagating.
22. The method of claim 20 wherein two of the respective excitation points locations are spaced apart by approximately a quarter wavelength of the reference wave.
23. The method of claim 20 wherein radiating the transmit signal includes radiating the transmit signal from an edge of the antenna element, the edge extending approximately parallel to a dimension along which the reference wave is propagating.
24. The method of claim 20 wherein radiating the transmit signal includes radiating the transmit signal from an edge of the antenna element, the edge extending approximately orthogonal to a dimension along which the reference wave is propagating.
25. The method of claim 20 , further comprising:
generating, in response to the transmit signal, at least one main transmit beam; and
steering each of the at least one main transmit beam by coupling another one of the intermediate signals to a respective location of the antenna element.
26. A method, comprising:
receiving a receive signal with an antenna element;
generating, at respective locations of the antenna element in response to the receive signal, respective intermediate signals each having a different phase; and
generating a reference wave in response to one of the intermediate signals.
27. The method of claim 26 wherein generating the reference wave includes coupling the one of the intermediate signals to a respective location of a transmission medium along which the reference wave is propagating.
28. The method of claim 26 wherein two of the respective locations are spaced apart by approximately a quarter wavelength of the receive signal.
29. The method of claim 26 wherein receiving the receive signal includes exciting the antenna element along an edge of the antenna element, the edge extending approximately parallel to a dimension along which the reference wave is propagating.
30. The method of claim 26 wherein receiving the receive signal includes exciting the antenna element with the receive signal along an edge of the antenna element, the edge extending approximately orthogonal to a dimension along which the reference wave is propagating.
31. The method of claim 26 , further comprising:
generating, in response to the receive signal, at least one main receive beam; and
steering each of the at least one main receive beam by generating the reference wave from another one of the intermediate signals.