This invention relates to radar and communication systems. More particularly, the invention relates to a switchable microwave fluidic polarizer for changing the polarization of signals associated with an antenna.
The trend toward lower cost and lighter weight active array antennas for radar systems has caused the focus on array architecture to evolve from developing brick and tile subarray assemblies toward thinner and lighter multilayer printed circuit board (PCB) panel subarray assemblies. In some antenna systems, monolithic microwave integrated circuit (MMIC) devices that can make up the transmit/receive (TR) modules are now generally mounted directly to the panel subarray.
A linearly polarized wave may be converted to a circularly polarized wave by means of a panel which provides a 90 degree difference in transmission phase between two crossed linear components. The panel is generally a meander line plate which is a dielectric slab with etched copper meander lines. The electric field of the wave incident to the panel is separated into two equal orthogonal components parallel (E-parallel) and perpendicular (E-perpendicular) to the meander line axis. The E-parallel components are delayed due to the inductive effective, and the E-perpendicular component is advanced due to the capacitive effect of the grating structure of the meander-line polarizers.
The meander-line polarizer has the advantages of broadband frequency operation with low insertion loss and ease of manufacturing. In the past, meander-line polarizers have been used to effect linear-to-circular polarization conversion and to cause a 90 degree rotation of a linearly polarized signal. The meander-line polarizer would then consist of several printed circuit sheets with etched-copper meander lines. The challenge for the future is adding such functionality in front of an active array antenna that is switchable and reconfigurable.
Aspects of the present invention relate to a switchable microwave fluidic polarizer. In one embodiment, the invention relates to a switchable polarizer for polarizing radio frequency (RF) signals associated with an antenna, the switchable polarizer/antenna including a plurality of radiating elements, an RF feed coupled to the plurality of radiating elements, an antenna input coupled to the RF feed, and an antenna cover disposed in proximity to the plurality of radiating elements, the antenna cover including a dielectric substrate including a plurality of channels for enclosing a liquid metal.
In one embodiment, in a first state, the switchable polarizer is configured to allow incident signals to pass without affecting a polarization of the incident signals, and, in a second state, the switchable polarizer is configured to change the polarization of incident signals from a linear polarization to a circular polarization. In such case, the channels are substantially empty of the liquid metal in the first state, and the channels are substantially filled with the liquid metal in the second state.
In another embodiment, the invention relates to a process for operating a switchable polarizer including an antenna cover disposed in proximity to a plurality of radiating elements, the antenna cover including a dielectric substrate having a plurality of channels for enclosing a liquid metal, the process including filling the plurality of channels with a liquid metal, in a first state, to change a polarization of signals incident to the switchable polarizer from a linear polarization to a circular polarization, and removing the liquid metal from the plurality of channels, in a second state, to allow signals incident to the switchable polarizer to pass without affecting the polarization of the incident signals.
a is a schematic block diagram illustrating a system having two pumps for controlling a flow of liquefied metal in one or more meander-line channels in accordance with one embodiment of the invention.
b is a schematic block diagram of the system of
a is a schematic block diagram illustrating a system having two pumps for controlling a flow of liquefied metal in a meander-line channel having a sliding piston for isolating fluids controlled by each pump in accordance with one embodiment of the invention.
b is a schematic block diagram illustrating the system of
Referring now to the figures, embodiments of the switchable polarizer include a dielectric material having a number of meander-line channels formed therein to enclose a liquid metal. In operation, the liquid metal can be forced into the meander-line channels using a pump or other means. In one embodiment, the same pump can be used to extract the liquid metal from the meander-line channels. When the meander-line channels are filled with liquid metal, embodiments of the switchable polarizers can change the polarization of signals incident to the switchable polarizer. When the channels are empty, embodiments of the switchable polarizers can leave unchanged the polarization of signals incident to the switchable polarizer (e.g., the switchable polarizer can be effectively transparent to the signals). In several embodiments, the dielectric material takes a sheet-like form that may include a number of dielectric layers and multiple arrays of meander-line channels. In some embodiments, a second pump is included to force the liquid metal from the meander-line channels.
In operation, the array antenna 12 generates one or more radiated signals 28 incident to the radome 14. When the meander-line channels are filled with the liquefied metal, the polarizer can change the polarization of the radiated incident signals 28 from a linear polarization to a circular polarization to produce a resultant radiated signal 30. When the meander-line channels are empty, the polarizer can appear transparent to signals incident to the radome, and thus polarization of such signals can remain unchanged.
In several embodiments, the two dielectric sheets of the radome are fused together to form the thin channelized cavities in between as shown in
In some embodiments, low temperature liquefied metal can be pumped into the channelized cavities to create the conductor pattern for a meander-line polarizer as shown in
In the embodiment illustrated in
a is a schematic block diagram illustrating a system 70 having two pumps (74, 75) for controlling a flow of liquefied metal 32 in one or more meander-line channels 72 in accordance with one embodiment of the invention. The system 70 includes the one or more meander-line channels 72 of a radome enclosing the liquefied metal 32 and a liquid dielectric 76. The first pump or metal pump 74 is coupled to one end of the meander-line channel 72 and to a metal storage container 78 for storing the liquefied metal 32.
The second pump or dielectric pump 75 is coupled to the other end of the meander line channel 72 and to an dielectric storage container 79 for storing the liquid dielectric 76. In several embodiments, the metal pump 74 is used to move the liquefied metal 32 from the metal storage container 78 into the meander-line channel 72, and/or additional meander-line channels, to form a switchable polarizer. The dielectric pump 75 can be used to force the liquid dielectric 76 into the channels 72 and to push the liquefied metal 32 out of the channels 72 and back into the metal storage container 78.
b is a schematic block diagram illustrating the system of
a is a schematic block diagram illustrating a system 80 having two pumps (84, 85) for controlling a flow of liquefied metal 32 in a meander-line channel 82 having a sliding piston 87 for isolating fluids controlled by each pump in accordance with one embodiment of the invention. The system 80 includes the one or more meander-line channels 82 of a radome enclosing the liquefied metal 32, a solid piston 87, and a liquid dielectric 86. The first pump or metal pump 84 is coupled to one end of the meander-line channel 82 and to a metal storage container 88 for storing the liquefied metal 82. The second pump or dielectric pump 85 is coupled to the other end of the meander-line channel 82 and to an dielectric storage container 89 for storing the liquid dielectric 86.
In several embodiments, the metal pump 84 is used to move the liquefied metal 32 from the metal storage container 88 into the meander-line channel 82, and/or additional meander line channels, to form a switchable polarizer. The dielectric pump 85 can be used to force the liquid dielectric 86 into the channels 82 and to push the liquefied metal 32 out of the channels 82 and back into the metal storage container 88. The solid piston 87 can be placed between the liquefied metal 32 and the liquid dielectric 86 to prevent mixing of the two fluids. The solid piston 87 can then be moved within the meander-line channel 82 based on the pressure applied from either of the two fluids. In the embodiment illustrated in
b is a schematic block diagram illustrating the system of
In operation, the array antenna 112 generates one or more radiated signals 128 incident to the curved radome 114. The meander-line channels 116 containing the liquefied metal change the polarization of the radiated incident signals 128 from a linear polarization to a circular polarization to produce a resultant radiated signal 130. In one embodiment, the meander-line channels 116 can also contain an air dielectric.
In several embodiments, the switchable polarizer can operate as described above for the embodiments of
In some embodiments, the process does not perform all of the actions described. In one embodiment, the process performs the actions in a different order than illustrated in the flow chart of
While the above description contains many specific embodiments of the invention, these should not be construed as limitations on the scope of the invention, but rather as examples of specific embodiments thereof. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.
Number | Name | Date | Kind |
---|---|---|---|
4498086 | Sandler | Feb 1985 | A |
5014022 | Wolfson et al. | May 1991 | A |
6202748 | Carisella et al. | Mar 2001 | B1 |
6674340 | Quan et al. | Jan 2004 | B2 |
6870511 | Lynch et al. | Mar 2005 | B2 |
7053849 | Pike et al. | May 2006 | B1 |
7262734 | Wood | Aug 2007 | B2 |
20030132890 | Rawnick et al. | Jul 2003 | A1 |
20040125019 | Rawnick et al. | Jul 2004 | A1 |
20050017905 | Rawnick et al. | Jan 2005 | A1 |
20050048934 | Rawnick et al. | Mar 2005 | A1 |
20050237267 | Brown et al. | Oct 2005 | A1 |
20070188398 | Mohuchy et al. | Aug 2007 | A1 |
Entry |
---|
Lake, “Liquid Metal Antenna”, http://www.hamdomain.com/lm-antenna/, Jun. 9, 2009 (4 pgs.). |
Extended European Search Report for European Application No. 11161314.7, Extended European Search Report dated Sep. 15, 2011 and mailed Sep. 23, 2011 (8 pgs.). |
Number | Date | Country | |
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20110109519 A1 | May 2011 | US |