Some embodiments of the present invention pertain to the generation and transmission of microwave and/or millimeter wave energy. Some embodiments relate to power combining. Some embodiments relate to wireless communication systems. Some embodiments relate to active array antenna systems.
Many conventional power-combining techniques generate high-power signal levels by combining the outputs of multiple transistor amplifiers or transistor-amplifier cells. These conventional techniques require complex matching networks due to the very low output impedances of the high-power devices. Other conventional power-combining techniques use stripline or microstrip circuits to combine the outputs of multiple amplifiers. These conventional power-combining techniques require significant circuit area compared with the area occupied by the amplifier devices. The failure of an amplifier device may result in an impedance mismatch that may significantly degrade the performance of the power combiner.
Thus, there are general needs for systems that can generate high-power signal levels that do not require complex matching networks. There are also general needs for systems that can generate high-power signal levels that do not require significant circuit area as compared with the area occupied by the amplifier.
The following description and the drawings sufficiently illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Examples merely typify possible variations. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments of the invention set forth in the claims encompass all available equivalents of those claims. Embodiments of the invention may be referred to herein, individually or collectively, by the term “invention” merely for convenience and without intending to limit the scope of this application to any single invention or inventive concept if more than one is in fact disclosed.
In accordance with embodiments of the present invention, the energy provided to ports 114 is not spatially combined in free space, as in a spatial combiner or phased-array. The energy is concurrently combined within and radiated by combining-radiating assembly 108. In some embodiments, combining-radiating assembly 108 may operate as an antenna that transmits the combined energy.
In some embodiments, combining-radiating assembly 108 may comprise a patch with ports 114 around the patch. The patch may combine signals 105 and may radiate coherent high-power wavefront 109. In these embodiments, the patch may operate as an antenna that transmits the combined energy. In some embodiments, ports 114 may be spaced uniformly around the patch. In some embodiments, the patch may be circular and ports 114 may be uniformly spaced (e.g., radially) around the patch, although the scope of the invention is not limited in this respect as other shaped patches may also be suitable. In some of these embodiments, the patch may comprise a conductive material having either a substantially circular shape or a substantially regular polygonal shape, although the scope of the invention is not limited in this respect. Some examples of the patch are discussed in more detail below. In some alternate embodiments, combining-radiating assembly 108 may comprise a linear-polarized horn antenna having an integrated coaxial-to-waveguide combiner to coherently combine energy from ports 114.
In some embodiments, the use of combining-radiating assembly 108 may lessen and possibly even eliminate the need for circuit-based power combiners. Furthermore, in some embodiments, polarization diversity may be achieved by selectively setting the phase at each port 114 of combining-radiating assembly 108. In addition, in some embodiments, control over the phase at each port 114 may allow power-combining system 100 to at least partially compensate for degradation and possibly even failure of one or more of the signal paths.
In some embodiments, power-combining system 100 may be used to transmit information wirelessly and may be part of a wireless communication system. In some other embodiments, power-combining system 100 may be part of an active array antenna system. These embodiments are described in more detail below.
In some embodiments, output signals 105 from coherent sources 104 may comprise either microwave or millimeter-wave frequency signals. In some embodiments, each of coherent sources 104 may provide one of output signals 105 whose phase is set by that of an associated one of input signals 103 provided by an associated one of phase controllers 102. In these embodiments, the microwave frequencies may generally range between approximately one and 30gigahertz (GHz) and the millimeter-wave signals may generally range between approximately 30 and 300 GHz, although the scope of the invention is not limited in this respect.
In some embodiments, each of coherent sources 104 may comprise a phase-locked oscillator to provide one of output signals 105 that is phase-locked to an associated one of input signals 103. In some embodiments, the output frequency and output phase of output signals 105 may be phase locked to common input signal 101, although the scope of the invention is not limited in this respect.
In some embodiments, each of coherent sources 104 may comprise up to several hundred or more small low-power amplifiers (e.g., one or more transistor cells) having relatively high input and output impedances (e.g., 50 Ohms), although the scope of the invention is not limited in this respect. These amplifiers may be matched using conventional microwave design techniques, although the scope of the invention is not limited in this respect. In some other embodiments, one or more of coherent sources 104 may comprise a traveling wave tube amplifier (TWTA) to provide output signals 105 whose phase is set by the phase of an associated one of input signals 103. In some other embodiments, one or more of coherent sources 104 may comprise a klystron amplifier or a solid-state amplifier, although other amplifiers may also be suitable. In these embodiments, the phase at the output of coherent sources 104 is determined by the phase at the input.
In some of these embodiments, coherent sources 104 generate output signals 105 of substantially uniform amplitude for combining and radiating by combining-radiating assembly 108, although in other embodiments, the amplitude of output signals 105 may be varied. These embodiments are discussed in more detail below.
As illustrated in
In some embodiments, controller 110 may provide for on-the-fly polarization by setting a phase of the signals at ports 114 to selectively provide one of a right-hand circularly polarized wavefront, a left-hand circularly polarized wavefront, a horizontally polarized wavefront or a vertically polarized wavefront.
In some embodiments, controller 110 may set the phase shifts for each of phase controllers 102 based on an initial calibration for each port 114. In some embodiments, memory 116 may store a predetermined phase offset and/or amplitude offset for each port 114 based on the initial calibration to provide the predetermined phase shift at each port 114 during operation. In these embodiments, controller 110 may cause phase controllers 102 to offset the phase and/or amplitude for each port 114 based on the predetermined phase offset and amplitude offset stored in memory 116. In some of these embodiments, phase controllers 102 may be phase and amplitude controllers. In these embodiments, during calibration, the phase and/or amplitude for each port 114 may be optimized so that reflected power at each port 114 is minimized. In these embodiments, rather than minimizing reflections and matching the input for each of ports 114 individually, reflections from all ports 114 may be minimized concurrently. In this way, maximum power may be transferred to combining-radiating assembly 108 for combining and radiating.
In some embodiments, power-combining system 100 may also include optional dual-directional couplers 106 in the signal path prior to ports 114. Dual directional couplers 106 may be used to measure incident and reflected power from ports 114 during operation. Data derived from these measurements may be used as part of a built-in-test system. Dual-directional couplers 106 may also be used to monitor reflected energy from ports 114 during calibration to determine the phase and/or amplitude offsets for use by controller 110.
In some embodiments, combining-radiating assembly 108 may have N ports 114 while possessing N-fold rotational symmetry. In these embodiments, combining-radiating assembly 108 may be geometrically invariant to rotations of 360/N degrees. In these embodiments, a phase progression of ±360 degrees divided by N may be set between ports 114 by controller 110 to generate coherent high-power wavefront 109 with either right-hand or left-hand circular polarization, depending on the sign of the phase progression.
In some embodiments, power-combining system 100 may be coupled to master controller and user interface 112. Master controller and user interface 112 may allow a user to select and set the type of polarization (i.e., right-hand circular, left-hand circular, vertical linear, horizontal linear) of coherent wavefront 109 as well as the power level of coherent wavefront 109. Master controller and user interface 112 may also be used during calibration. In some embodiments, master controller and user interface 112 may be used to steer and/or direct coherent high-power wavefront 109 in various directions, although the scope of the invention is not limited in this respect. These embodiments are discussed in more detail below.
In some four-port embodiments (i.e., N=4), four ports 204A, 204B, 204C and 204D may generate coherent wavefront 109 (
In these four-port embodiments when four ports 204A, 204B, 204C and 204D are used to generate coherent wavefront 109 (
In some embodiments, patch 202 may have a circular shape, as illustrated in
In some eight port embodiments (N=8), eight ports may be used to generate a wavefront with either right-hand or left-hand circular polarization. In some other eight port embodiments, eight ports may be used to generate a coherent wavefront with a linear polarization. These embodiments are described in more detail below.
In some embodiments, first and second non-conductive substrates 212 & 216 may comprise printed circuit boards (PCBs), such as Duroid or alumina, although other non-conductive substrate materials may also be suitable. In some embodiments, patch 202, conductive strips 206 and ground plane 218 may comprise a conductive material such as copper, gold, aluminum and/or silver, although the scope of the invention is not limited in this respect.
In some embodiments, ports 204 may comprise electromagnetically-coupled ports. In these embodiments, electromagnetic signals 203 may be coupled between conductive strips 206 and patch 202. In these embodiments, each port 204 may comprise an open-ended conductive strip 206 disposed on non-conductive substrate 216 to couple electromagnetic energy from each conductive strip 206 to patch 202. In these embodiments, open-ended conductive strips 206 may extend and terminate under patch 202 as illustrated. In these electromagnetically-coupled embodiments, open-ended conductive strips 206 may be electrically insulated from patch 202, although the scope of the invention is not limited in this respect. In some of these embodiments, open-ended conductive strips 206 may comprise microstrip feed lines, although the scope of the invention is not limited in this respect.
In the embodiments illustrated in
In these eight port embodiments (N=8), to generate wavefront 109 (
Although patch 302 is illustrated as having a circular shape, the scope of the invention is not limited in this respect. In alternate embodiments, patch 302 may have regular polygonal shape (e.g., octagonal).
In some alternate embodiments, ports 304A-304H may be used to generate wavefront 109 (
In the embodiments illustrated in
In
In some embodiments, master controller and user interface 112 may include one or more controllers, such as controller 110 (
Although power-combining system 100 (
The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims.
In the foregoing detailed description, various features are occasionally grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention may lie in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment.