Low loss microelectromechanical system (MEMS) phase shifter
A phase shifter comprising an actuator coupled to a dielectric. When the dielectric is inserted into the waveguide in response to actuation by the actuator, the phase velocity of the incoming electromagnetic wave is decreased, resulting in a phase shift of the electromagnetic wave. A desired phase shift and a low insertion loss can be controlled by positioning of the dielectric and engineering the permittivity of the dielectric.
1. A device, comprising:
at least one phase shifter comprising:
a dielectric material comprising a pattern of holes; and
an actuator connected to the dielectric material, the actuator comprising a micro-electromechanical system comprising a motor; and wherein:
a first actuation of the at least one phase shifter by the actuator moves the dielectric material towards an electromagnetic wave so that an interaction of the dielectric material with the electromagnetic wave causes a phase shift of the electromagnetic wave, and
a second actuation of the at least one phase shifter by the actuator moves the dielectric material away from the electromagnetic wave.
2. The device of claim 1 , wherein the dielectric material comprises:
an input region having a first permittivity for the electromagnetic wave incident on the dielectric material through the input region;
a transmission region interfacing with the input region and having a second permittivity for the electromagnetic wave transmitted through the input region to the second region; and
wherein the second permittivity is larger than the first permittivity.
3. The device of claim 1 , wherein the dielectric material comprises:
an input region having a first permittivity tailoring an impedance match of the dielectric material to a waveguide guiding the electromagnetic wave;
a transmission region interfacing with the input region and having a second permittivity for the electromagnetic wave transmitted through the input region to the transmission region; and
an output region interfacing with the transmission region, the output region tailoring an impedance match of the dielectric material to the waveguide for the electromagnetic wave transmitted from the transmission region and through the output region to the waveguide.
4. The device of claim 3 , wherein the first permittivity tailors the impedance match so that 3% or less of the power of electromagnetic wave incident on the dielectric material is reflected from the dielectric material.
5. The device of claim 3 , wherein:
the at least one phase shifter comprises the dielectric material and the pattern of holes in the dielectric material,
the holes have a width and a spacing, and
an aspect ratio comprising the width divided by the spacing is different in the input region as compared to in the transmission region.
6. The device of claim 1 , further comprising:
a waveguide configured and dimensioned to guide the electromagnetic wave having a frequency in a range of 100 gigahertz (GHz) to 1000 terahertz (THz), wherein:
the first actuation moves the dielectric material into the waveguide, and
the second actuation moves the dielectric material out of the waveguide.
7. The device of claim 6 , wherein the waveguide comprises a hollow waveguide having a rectangular cross-section and a metal surface.
8. The device of claim 1 , further comprising:
a first block comprising one or more first sections of one or more waveguides;
a second block comprising one or more second sections of the one or more waveguides; and
the at least one phase shifter between the first block and the second block such that each of the first sections mate with one of the second sections to form one of the waveguides guiding the electromagnetic wave and each of the waveguides are coupled to one of the phase shifters.
9. The device of claim 1 , wherein the actuator comprises a comb drive.
10. The device of claim 1 , further comprising:
a phased array antenna system comprising a plurality of antennas;
a plurality of the at least one phase shifter;
a plurality of the at least one actuator;
a plurality of waveguides, each of the waveguides:
feeding one of the plurality of antennas with the electromagnetic wave so as to generate an output electromagnetic wave; and
coupled to one of the phase shifters so that each of the actuators moves one of the phase shifters into the electromagnetic wave guided by the waveguide coupled to the one of the phase shifters.
11. The device of claim 10 , further comprising a plurality of the actuators and a computer controlling the actuators so as to independently move each of the phase shifters, each of the phase shifters comprising a different permittivity and/or moved by different amounts, thereby shifting the phase of the electromagnetic wave in each of the waveguides by different amounts so as to steer a beam of electromagnetic radiation outputted from the antennas.
12. The device of claim 11 , wherein the computer controls the actuators with a digital signal so that the phase shifters digitally shift the phase of the electromagnetic waves according to the digital signal.
13. The device of claim 11 , wherein the computer controls the actuators with an analog signal so that the phase shifters shift the phase of the electromagnetic waves according to the analog signal.
14. A remote sensing system comprising the device of claim 10 , wherein the electromagnetic radiation is used to perform remote sensing.
15. A communications system comprising the device of claim 10 , wherein the electromagnetic radiation transmits a signal.
16. A method of making a device, comprising:
etching a dielectric material with a pattern of holes; and
providing at least one actuator connected to the dielectric material, forming a phase shifter, wherein the actuator is configured to move the dielectric material towards or away from an electromagnetic wave so as to shift a phase of the electromagnetic wave interacting with the dielectric material.
17. The method of claim 16 , wherein providing the actuator comprises etching a micro-electromechanical system structure in a wafer.
18. The method of claim 16 , wherein the providing comprises:
providing a silicon wafer including a buried oxide layer;
thermally oxidizing the silicon wafer to form a first thermal oxide on a front side of the silicon wafer and second thermal oxide on a back side of the silicon wafer, under conditions to avoid thermal shock to the silicon wafer;
depositing photoresist on the first thermal oxide;
patterning the first thermal oxide with the pattern and a first side of the actuator structure using photolithography and the photoresist;
etching the pattern of the holes and the first side of the actuator structure in the first thermal oxide using inductively coupled plasma etching;
patterning the second thermal oxide with a second side of the actuator structure on an area of the silicon wafer to the side of the pattern of holes;
etching the second side of the actuator structure in the second thermal oxide using inductively coupled plasma etching;
deep reactive ion etching the silicon wafer using the first thermal oxide as a first mask and a first side of the buried oxide layer as an etch stop, to define the pattern of holes and the first side of the actuator structure in the silicon wafer;
deep reactive ion etching the second side of the silicon wafer using the second thermal oxide as a mask and the buried oxide layer as an etch stop to:
define a cavity behind the pattern of holes in the backside of the silicon wafer, and
define the second side of the actuator structure in the backside of the silicon wafer; and
removing the first thermal oxide layer, the second thermal oxide layer, and the exposed buried oxide layer so that the actuator structure comprising an arm connected to the pattern of holes can move.
19. The method of claim 16 , further comprising:
machining a first metal block so as to form a first section of a waveguide in the first metal block;
machining a second metal block so as to form a second section of the waveguide in the second block; and
assembling the phase shifter between the first metal block and the second metal block so as to form the waveguide comprising the first section mating with the second section and the phase shifter coupled to the waveguide guiding the electromagnetic wave.
20. The method of claim 16 , wherein the dielectric material comprises:
an input region having a first permittivity for the electromagnetic wave incident on the dielectric material through the input region;
a transmission region interfacing with the input region and having a second permittivity for the electromagnetic wave transmitted through the input region to the second region; and
wherein the second permittivity is larger than the first permittivity.
21. A device, comprising:
at least one phase shifter comprising:
a dielectric material; and
an actuator connected to the dielectric material, the actuator comprising a micro-electromechanical system comprising a motor etched in a wafer; and wherein:
a first actuation of the at least one phase shifter by the actuator moves the dielectric material towards an electromagnetic wave so that an interaction of the dielectric material with the electromagnetic wave causes a phase shift of the electromagnetic wave, and
a second actuation of the at least one phase shifter by the actuator moves the dielectric material away from the electromagnetic wave.