The present disclosure relates generally to electronically scanned arrays, and more particularly to utilizing outphasing transmitter for electronically scanned arrays.
An active electronically scanned array (ESA), also known as an active electronically steered antenna, is a type of phased array whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules. Active ESAs aim their beam by emitting separate radio waves from each module that interfere constructively at certain angles in front of the antenna. Another type of ESA, referred to as the passive ESA, is a phased array which has a central radio frequency source (such as a magnetron, a klystron, a travelling wave tube or solid state amplifier), sending energy into (usually digitally controlled) phase shift modules, which then send energy into the various emitting elements in the front of the antenna.
An ESA will be confined to a limited area set by its application and platform installation. The pitch between adjacent elements is about half of the wavelength of the carrier and as frequency increases, the pitch between adjacent elements decreases. The efficiency of the transmitter typically degrades over the frequency. Therein lies a need to provide high efficiency transmitters for ESAs.
The present disclosure is directed to an outphasing transmitter for an ESA. The outphasing transmitter includes a phase shifting device. The phase shifting device is configured for phase shifting an input signal and providing a pair of phase shifted signals for each emitting element of the EAS. The outphasing transmitter also includes an outphasing power amplifier associated with each emitting element. Each outphasing power amplifier is configured for separately amplifying the pair of shifted signals for each emitting element and combining the separately amplified signals for each emitting element for transmission.
Another embodiment of the present disclosure is directed to an outphasing transmitter for an ESA. The outphasing transmitter includes an outphasing power amplifier configured for amplifying an input signal utilizing outphasing amplification to produce an amplified input signal. The outphasing transmitter also includes a splitter in communication with the outphasing power amplifier, wherein the splitter is configured for splitting the amplified input signal into a plurality of signals for a plurality of emitting elements. The outphasing transmitter further includes a plurality of phase shifters, and each of the plurality of phase shifters is configured for phase shifting a particular signal of the plurality of signals based on a particular offset phase.
A further embodiment of the present disclosure is directed to a method for utilizing outphasing amplification in an ESA. The method includes: phase shifting an input signal and providing a pair of phase shifted signals for each emitting element of the plurality of emitting elements; separately amplifying the pair of shifted signals for each emitting element; and combining the separately amplified signals for each emitting element for transmission.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.
The numerous objects and advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:
Reference will now be made in detail to exemplary embodiments of the disclosure, examples of which are illustrated in the accompanying drawings.
The present disclosure is directed to high efficiency transmitters for electronically scanned arrays (also known as electronically steered antennas or ESAs). The transmitters in accordance with the present disclosure utilize outphasing power amplification. Outphasing power amplification is a complex (amplitude and phase) modulation technique achieved by summing a pair of constant amplitude and phase modulated carriers. As illustrated in
Referring to
It is contemplated that the number of emitting elements utilized by the ESA may be greater than two, and in such configurations, the phase shifting device 102 may be utilized to provide phase shifting for various emitting elements based on various offset values. As mentioned above, the offset values for the various emitting elements can be programmable and can be determined as a part of the operation of the ESA without departing from the spirit and scope of the present disclosure. It is also understood that the signals provided to certain emitting elements may not need to be offset (again, how to offset the emitting elements is determined as a part of the ESA operation), and for such emitting elements, the offset phase may be set to zero.
In addition to providing offset phase shifting among the various emitting elements, the phase shifting device 102 also applies additional phase shifting for each particular emitting element. This additional phase shifting is referred to as the “delta phase” in the present disclosure, which is used to generate a pair of signals for an outphasing amplifier associated with each particular emitting element of the ESA. More specifically, as shown in
It is contemplated that utilizing outphasing power amplifiers 108 and 110 as described above improves the overall efficiency of the transmitter array by not only increasing the efficiency of individual element but also digitally adjusting the elements for optimal operation. In the outphasing topology, each power amplifier can be tuned individually to maximize its efficiency. In addition, it is contemplated that the delta phase value can be programmable and can be adjusted to maintain the efficiency of the ESA and account for gain imbalance and/or phase imbalance between the amplifier pairs. For instance, the delta phase value can be set to provide the maximum power-added efficiency (PAE) or the desired power output. It is also contemplated that adjusting the delta phase value in turn adjusts the output power of the ESA without having to change the input power. This allows the output power of the ESA to be adjusted while still maintaining its efficiency, even when the power is back off from the peak. Furthermore, using the outphasing transmitters as described above still allows the output power to be adjusted by changing the input power if needed.
It is understood that while the block diagram shown in
Referring to
Regardless of the differences between the implementations shown in
In one embodiment, the phase shifting device is implemented utilizing a multifunction silicon-germanium (SiGe) chip and the outphasing power amplifiers are implemented utilizing a gallium nitride monolithic microwave integrated circuit (GaN MMIC). The SiGe chip and the GaN MMIC may be further configured to support ESA operations in X-band. It is contemplated, however, that the phase shifting devices and the outphasing power amplifiers described above are merely exemplary, and various types of phase shifting devices and outphasing power amplifiers may be utilized to implement the outphasing transmitter without departing from the spirit and scope of the present disclosure.
Referring now to
Furthermore, it is contemplated that the outphasing power amplifier may be utilized in a similar manner as described above, but adapted for passive ESAs. Referring to
It is understood that the present disclosure is not limited to any underlying implementing technology. The present disclosure may be implemented utilizing any combination of software and hardware technology. The present disclosure may be implemented using a variety of technologies without departing from the scope and spirit of the disclosure or without sacrificing all of its material advantages.
It is understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
It is believed that the present disclosure and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction, and arrangement of the components thereof without departing from the scope and spirit of the disclosure or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof, it is the intention of the following claims to encompass and include such changes.
Number | Name | Date | Kind |
---|---|---|---|
H173 | Claborn et al. | Dec 1986 | H |
4835493 | Walsh, Jr. | May 1989 | A |
5329301 | Balzeit et al. | Jul 1994 | A |
6031022 | Martin et al. | Feb 2000 | A |
6133788 | Dent | Oct 2000 | A |
6825719 | Barak et al. | Nov 2004 | B1 |
7684776 | Nation | Mar 2010 | B2 |
8290086 | Bose et al. | Oct 2012 | B2 |
8872719 | Warnick | Oct 2014 | B2 |
20030034916 | Kwon et al. | Feb 2003 | A1 |
20030162566 | Shapira et al. | Aug 2003 | A1 |
20030227353 | Fayyaz | Dec 2003 | A1 |
20040263242 | Hellberg | Dec 2004 | A1 |
20050156800 | Sankaranarayanan | Jul 2005 | A1 |
20050280466 | Gailus et al. | Dec 2005 | A1 |
20090012768 | Son et al. | Jan 2009 | A1 |
20090034603 | Lakdawala et al. | Feb 2009 | A1 |
20090262037 | Matyas et al. | Oct 2009 | A1 |
20100074367 | Kim et al. | Mar 2010 | A1 |
20100171674 | Henderson | Jul 2010 | A1 |
20100244949 | Gustavsson et al. | Sep 2010 | A1 |
20100301933 | Lejon | Dec 2010 | A1 |
20110102262 | Haskell | May 2011 | A1 |
20120033559 | Kim | Feb 2012 | A1 |
20120050107 | Mortazawi et al. | Mar 2012 | A1 |
20120155573 | Pruvost | Jun 2012 | A1 |
20120207252 | Levesque et al. | Aug 2012 | A1 |
20120319901 | Pruett et al. | Dec 2012 | A1 |
20130033296 | Kishimoto | Feb 2013 | A1 |
20130147664 | Lin | Jun 2013 | A1 |
20130176186 | Yaccarino et al. | Jul 2013 | A1 |
20130314280 | Maltsev et al. | Nov 2013 | A1 |
20140266465 | Kermalli | Sep 2014 | A1 |
20140334531 | Jeckeln | Nov 2014 | A1 |