Patent Application
20100214171
The present invention relates generally to radar and communication systems. More specifically, the invention relates to radar or communication systems that include a low cost multi-channel thinned transmit/receive (TR) module architecture that features fewer components than conventional TR modules.
Large area multifunction active arrays are used in radar and communication systems. In radar systems, the active arrays use electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. Active array antennas are typically electrically steerable. Thus, unlike mechanical arrays, active arrays are capable of steering the electromagnetic waves without physical movement. As active array antennas do not require systems for antenna movement, they are less complex (e.g., no moving parts), are more reliable, and require less maintenance than their mechanical counterparts. Other advantages over mechanically scanned arrays include a fast scanning rate, substantially higher range, ability to track and engage a large number of targets, low probability of intercept, ability to function as a radio/jammer, and simultaneous air and ground modes.
Active array antennas include a number of transmit/receive (TR) modules for transmitting and receiving electromagnetic waves, and a number of radiating elements. Typically, there is one TR module for each antenna radiating element. Each TR module generally includes a power amplifier (PA) for transmitting electromagnetic waves, a low noise amplifier (LNA) for receiving electromagnetic waves, a phase shifter for changing phase angles of the electromagnetic waves and transmit/receive (TR) switches for toggling transmit or receive functions. An example of a conventional active array antenna architecture including multiple conventional TR modules can be found in U.S. Pat. Publ. No. 2008/0088519, the entire content of which is expressly incorporated herein by reference. Other examples of conventional TR modules can be found in U.S. Pat. No. 5,339,083 to Inami and U.S. Pat. No. 6,992,629 to Kerner et al., the entire content of each reference document is expressly incorporated herein by reference.
Conventional TR modules for active arrays dissipate substantial power and include expensive components that contribute to antenna weight. Passive electronically scanned arrays (ESA) that use MEMS and varactor type phase shifters dissipate little power but have a high noise figure due to losses associated with the phase shifters and the associated RF feed network. In conventional active arrays, the noise figure is set by the LNA and loss in the path before the LNA. However, the collective power dissipation associated with conventional TR modules and their LNAs is often too high to meet the requirements of new applications. Future applications of active array antennas require reduced power dissipation, reduced cost, and reduced weight.
Aspects of the invention relate to a low cost multi-channel thinned transmit/receive (TR) module architecture. In one embodiment, the invention relates to an active antenna assembly including at least one multi-channel TR module for reducing power consumption, the antenna assembly including the at least one TR module including a first phase shifter, a first switch coupled to the first phase shifter, the first switch configured to switch between a transmit circuit and a receive circuit, the transmit circuit including a first power amplifier coupled to the first switch and to a plurality of second phase shifters, and a plurality of second power amplifiers, each second power amplifier coupled to one of the second phase shifters, the receive circuit including a low noise amplifier coupled to the first switch and to a plurality of third phase shifters, and a plurality of second switches, each second switch configured to switch between one of the second power amplifiers and one of the third phase shifters.
In another embodiment, the invention relates to a multi-channel TR module for reducing power consumption on receive, the TR module including a first phase shifter, a first switch coupled to the first phase shifter, the first switch configured to switch between a transmit circuit and a receive circuit, the transmit circuit including a first power amplifier coupled to the first switch, four second phase shifters, a power divider circuit for coupling the first power amplifier to the four second phase shifters, and four second power amplifiers, each second power amplifier coupled to one of the second phase shifters, the receive circuit including a low noise amplifier coupled to the first switch, four third phase shifters, and a power combiner circuit for coupling the low noise amplifier and the four third phase shifters, and four second switches, each second switch configured to switch between one of the second power amplifiers and one of the third phase shifters.
a is a schematic block diagram illustrating an active array antenna architecture including a plurality of four channel TR modules in accordance with one embodiment of the present invention.
b is a schematic block diagram illustrating an assembly including one of the plurality of four channel TR modules of
a is a schematic block diagram illustrating 4 to 1 TR module thinning in elevation in accordance with one embodiment of the present invention.
b is a schematic block diagram illustrating 4 to 1 TR module thinning in azimuth in accordance with one embodiment of the present invention.
c is a schematic block diagram illustrating 2 to 1 TR module thinning in both azimuth and elevation in accordance with one embodiment of the present invention.
Referring to the drawings, embodiments of multi-channel thinned TR modules include fewer components than conventional multi-channel TR modules. The improved TR modules therefore are less expensive, dissipate less power and weigh less than conventional TR modules. Embodiments of improved TR modules include separate internal beamforming networks for transmit and receive paths, multiple power amplifiers for amplifying signals in the transmit path, multiple phase shifters for changing phase angle, and multiple TR switches for switching between beamforming networks. Embodiments of improved TR modules eliminate low noise amplifiers (LNAs) generally required for conventional TR modules. These improved TR modules can be implemented in multi-layer assemblies. In one embodiment, the improved TR modules are implemented in a three layer assembly where the beamforming networks are located on different layers. In another embodiment, the improved TR modules are implemented in a two layer assembly where the beamforming networks are located on different layers.
a is a schematic block diagram of an active array antenna architecture 100 including a plurality of four channel TR modules 102 in accordance with one embodiment of the present invention. The antenna architecture 100 further includes a circulator 110 coupled to a planar RF feed unit 108, which is coupled to five first level RF feed units 106. The first level RF feed units 106 are coupled to the four channel TR modules 102. Each four channel TR module 102 is coupled to four radiating elements 104.
In operation, the circulator 110 routes outgoing and incoming signals between the antenna, including components from the planar RF feed unit 108 to the radiating elements 104, the transmitter (not shown) and the receiver (not shown). The operation of circulators within antenna systems is well known in the art. For example, U.S. Pat. No. 6,611,180 to Puzella et al., the entire content of which is expressly incorporated herein by reference, describes a circulator assembly and operation thereof. In addition, U.S. Pat. No. 7,138,937 to Macdonald, the entire content of which is expressly incorporated herein by reference, describes another circulator system. In some embodiments, the transmitter and receiver operate in the X-Band, or in a range from approximately 7 to 12.5 gigahertz (GHz). The planar RF feed unit 108 and first level RF feed units 106 distribute and concentrate electromagnetic signals in the X-Band, while transmitting and receiving those electromagnetic signals, respectively.
In the illustrated embodiment, each TR module is coupled to four radiating elements. In other embodiments, each TR module can be coupled to more than or less than four radiating elements. In some embodiments, each TR module can be coupled to a different number of radiating elements. In the embodiment illustrated in
b is a schematic block diagram illustrating an assembly 150 including one of the plurality of four channel TR modules, of
Signals received at each of the four radiating elements 104 travel into the TR module 102 via a radiating I/O 128 and are switched at the secondary TR switch 126 to a receive power combiner circuit or beamforming network 132. The power combiner circuit 132 combines the signals received from all four of the channels (e.g., the four radiating elements 104). The combined signal output of the power combiner circuit 132 is amplified by a low noise amplifier (LNA) 130 and then passes the primary TR switch 116 switched to the receive circuit. The received signals are then phase shifted by primary phase shifter 114 and exit the TR module at the RF feed 110112. In some embodiments, the low noise amplifier is a special type of electronic amplifier typically used in communication systems to amplify weak signals captured by an antenna.
In the embodiment illustrated in
In some embodiments, the primary phase shifter 114 is a low loss and low power dissipating type phase shifter implemented using micro-electromechanical systems (MEMs) and/or varactor diode devices. In one such embodiment, the phase shifters prevent grating lobes when scanning an antenna beam. In one embodiment, the primary phase shifter 114 is a 180 degree phase shifter that is larger than the secondary phase shifters 134. In some embodiments, the secondary phase shifters 134 are 2 to 3 bit phase shifters, which can typically be smaller and less lossy than other phase shifters. In several embodiments, the secondary phase shifters include at least two phase bits.
In some embodiments, the TR modules effectively provide 4 to 1 thinning by reducing the number of LNAs, phase shifters and/or other components typically required in conventional TR modules. In such case, the thinned TR modules can reduce receive power dissipation by up to 6 dB or more, can increase the receive noise figure, and can reduce phase shifter losses.
In the illustrated embodiment, a four channel TR module is used to thin components generally required in conventional TR modules. In other embodiments, the improved TR modules can use more than or less than four channels to decrease power dissipation and improve overall performance. In one such embodiment, for example, the improved TR modules include just two channels. In another embodiment, the improved TR modules include eight channels.
The thinned TR modules can be used in a number of different array antenna assemblies. In specific embodiments, for example, the thinned TR modules can be used in a brick array, a co-planar tile array, and/or a laminated panel array. In other embodiments, the improved TR modules can be used in other active arrays for radar or communication applications. In one embodiment, the improved TR modules can be used in any number of applications using one or more TR modules.
In some embodiments, the asymmetrically thinned four channel TR module can be implemented on a single die made of silicon germanium. In one embodiment, the asymmetrically thinned four channel TR module can be implemented on a single silicon germanium die with a number of discrete devices coupled to the die. In a number of embodiments, the size of the die can be increased or decreased based on the number of components to be included.
In
In some embodiments, the LNA can be made of any combination of gallium arsenide, indium phosphate, and/or antimonide based compound semiconductors. In various embodiments, the power amplifiers can be made of any combination of gallium arsenide, indium phosphate, and/or gallium nitride. In other embodiments, the components can be made of other materials.
In other embodiments, a thinned TR module can be implemented on a single layer or on more than three layers. In some embodiments, other circuit packaging variations can be used. In the embodiment illustrated in
In a number of embodiments, the TR modules are used in active array antennas. In other embodiments, the TR modules can be used in other wireless communication applications.
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.
