Abstract:
An apparatus and methods for operating a single quasi-optical structure are disclosed. The apparatus operates as an amplifier or an oscillator. The method disclosed teaches how to operate the single quasi-optical structure as an amplifier or an oscillator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to co-pending application U.S. application Ser. No. 11/347,707, filed on the same date as the present application, for “Lens Structure for Coupling Power” by Jonathan Lynch, the disclosure of which is incorporated herein by reference. This application is related to co-pending application U.S. application Ser. No. 10/664,112, filed on Sep. 17, 2003, for “Bias Line decoupling method for monolithic amplifier arrays” by Jonathan Lynch, the disclosure of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   This technology relates to a single quasi-optical structure capable of operating as an amplifier or an oscillator. 
   BACKGROUND AND PRIOR ART 
   Power is difficult to produce at millimeter wave frequencies due to the low power output of transistors and the losses incurred by traditional power combiners at these frequencies. Free space combining, also called “quasi-optical” combining, eliminates the latter problem by allowing electromagnetic energy to combine in free space. Quasi-optical arrays can provide high power by combining the outputs of many (e.g. thousands) of elements. 
   Quasi-optical amplifiers arranged in arrays have been developed by a number of groups to produce high output powers at millimeter wave frequencies. These amplifier arrays amplify incoming radiation, either through reflection or transmission, and reradiate energy typically in a (more or less) gaussian mode. The amplifiers usually utilize crossed input and output polarizations in order to reduce input/output coupling and avoid oscillation. 
   Quasi-optical sources (oscillators) arranged in arrays have also been developed for millimeter wave power, and consist of a number of individual oscillators that are coupled together so that they mutually synchronize in phase and the radiation from all the elements combines coherently, typically in a (more or less) gaussian mode in front of the oscillator array. A number of different methods exist to realize the coupling network, from printed circuit transmission lines to partial reflectors. The key is to provide strong coupling between elements to ensure in-phase oscillation. 
   Many quasi-optical oscillator arrays utilize hardwire circuitry (e.g. printed circuits, waveguides) to couple together the oscillating elements. For these types of arrays it is very difficult to control or modify the coupling in real time, without resorting to complicated schemes that are difficult to realize. For quasi-optical arrays that utilize partial reflectors, the oscillators are usually one port devices (negative resistance oscillators) with a single polarization output, which increases parasitic mutual coupling, creating difficulty in controlling the coupling between elements. 
   The present disclosure takes quasi-optical arrays one step further by allowing the amplifier coupling to be easily controlled so that the array can be operated as an amplifier or as a coherent source, depending on the amount of array coupling set by the user. 
   SUMMARY 
   According to the present disclosure, quasi-optical structures capable of operating as an amplifier or an oscillator are disclosed. 
   According to a first aspect, an electromagnetic array structure capable of operating as an amplifier or an oscillator is disclosed, comprising: a plurality of active amplification devices arranged in an array, wherein an input of each active amplification device is cross polarized with respect to an output of each active amplification device, a curved partial reflector disposed in a spaced relation with 
   the plurality of active amplification devices, a plurality of elongated conductors disposed along a first major surface of said partial reflector at a first angle to the input of the plurality of active amplification devices so as to couple cross polarized input and output of each active amplification device, wherein said electromagnetic array operates as an amplifier by setting said first angle so as to cause incoming energy to be absorbed by the input of each active amplification device, amplified and reradiated in the crossed polarization from the output of each active amplification device and said electromagnetic array operates as an oscillator by setting said first angle so as to induce oscillations and synchronize said plurality of active devices to produce coherent power 
   According to a second aspect, an electromagnetic array structure is disclosed, comprising: a plurality of active amplification devices arranged in an array, wherein an input of each active amplification device is cross polarized with respect to an output of each active amplification device, a partial reflector disposed in a spaced relation with the plurality of active amplification devices, wherein said partial reflector contains at least one curved major surface, a plurality of elongated conductors in a curved plane disposed in or on said reflector at a first angle to the input of the plurality of active amplification devices so as to couple cross polarized input and output of each active amplification device. 
   According to a third aspect, a method for operating an electromagnetic array structure as an amplifier or an oscillator is disclosed, comprising: arranging a plurality of active amplification devices in an array, wherein an input of each active amplification device is cross polarized with respect to an output of each active amplification device, providing a curved partial reflector rotationally in a spaced relation with the plurality of active amplification devices, providing a plurality of conductors along a first major surface of said partial reflector at a first angle to the input of plurality of active amplification devices so as to couple cross polarized input and output of each active amplification device, rotating said curved partial reflector to a first position so as to cause an incoming energy to be absorbed by the input of each active amplification device, amplified and reradiated in the crossed polarization from the output of each active amplification device, rotating said curved partial reflector to a second position so as to synchronize said plurality of active devices to produce coherent power. 

   
     BRIEF DESCRIPTION OF THE FIGURES AND THE DRAWINGS 
       FIG. 1  depicts an array of amplification devices; 
       FIG. 2  depicts an amplification device; 
       FIG. 3  depicts a reflector in accordance with the present disclosure; 
       FIG. 4  depicts a side view of section C of the reflector in  FIG. 3  in accordance with the present disclosure; 
       FIG. 5  depicts an exemplary embodiment of an amplifier/oscillator apparatus in accordance with the present disclosure; 
       FIG. 6  depicts a top view of the array of amplification devices for the apparatus in  FIG. 5  in accordance with the present disclosure; 
       FIG. 7  depicts a top view of a reflector in relation to the array of the amplification devices for the apparatus in  FIG. 5  in accordance with the present disclosure; 
       FIG. 8  depicts a top view of the reflector in relation to the array of amplification devices for the apparatus in  FIG. 5  in accordance with the present disclosure; 
       FIG. 9  depicts another exemplary embodiment of an amplifier/oscillator apparatus in accordance with the present disclosure; 
       FIG. 10  depicts a top view of the array of amplification devices for the apparatus in  FIG. 9  in accordance with the present disclosure; 
       FIG. 11  depicts the amplification devices of  FIG. 5  in amplification mode in accordance with the present disclosure; 
       FIG. 12  depicts the amplification devices of  FIG. 5  in oscillation mode in accordance with the present disclosure; 
       FIG. 13  depicts atop view of a reflector in relation to array of amplification devices for apparatus in  FIG. 12 ; 
       FIG. 14  depicts another exemplary embodiment of an oscillator apparatus in accordance with the present disclosure; 
       FIG. 15  depicts a top view of the reflector in relation to array of the amplification devices for the apparatus in  FIG. 14  in accordance with the present disclosure. 
   

   DETAILED DESCRIPTION 
   The present disclosure provides an apparatus and a method for generating high power either as a source or as an amplifier at millimeter wave frequencies, using an array of amplification devices and associated circuitry. The disclosed apparatus produces high output power as either an amplifier or as a source with a very simple change of configuration. This permits the end user to choose whichever configuration applies to his application, and allows the manufacturer to fabricate a single unit serving dual purposes, thus reducing costs. 
   The disclosed apparatus utilizes amplification devices  10  with crossed input/output polarizations arranged in an array  15 , as depicted in  FIGS. 1 and 2 . The amplification device  10  depicted in  FIGS. 1 and 2  includes a ground plane (not shown), two patch antennas, namely input antenna  25  and output antenna  26 , as well as an amplifier  30 , and a bias grid  35  supplying bias voltage to the amplifier  30 , as disclosed in more detail in U.S. patent application Ser. No. 10/664,112, which is incorporated herein by reference in its entirety. It is to be understood that patch antennas are only used as an example and that radiating elements like horn, slot, cavity backed slot, cavity backed patch, and dipole, can also be used for the disclosed apparatus. 
   The input antennas  25 , as depicted in  FIGS. 1 and 2 , are polarized in the X direction by outputting the incoming energy at point A of the input antennas  25 . Hence, only the energy polarized in the X direction will propagate from the input antennas  25  to the amplifiers  30 . The output antennas  26 , as depicted in  FIGS. 1 and 2 , are polarized in the Y direction by inputting amplified energy from the amplifiers  30  at point B of the output antennas  26 . Hence, the output antennas  26  will reradiate the energy polarized in the Y direction. 
   Although the input antennas  25 , depicted in  FIGS. 1 and 2 , are polarized in the X direction and the output antennas  26 , depicted in  FIGS. 1 and 2 , are polarized in the Y direction, it is to be understood that the input antennas  25  can be polarized in any direction. However, maintaining a cross polarization of the input antennas  25  and output antennas  26  reduces parasitic coupling and improves the coupling control as will become evident below. 
   The disclosed apparatus further utilizes curved partial reflector  20  with conductors  50  disposed on the reflector&#39;s  20  surface, as depicted in  FIG. 3  and  FIG. 4 .  FIG. 3  depicts a top view of the reflector  20  and  FIG. 4  depicts the section C side view of the reflector  20  depicted in  FIG. 3 . 
   Although the conductors  50  in  FIG. 3  are represented as straight lines, it shall be understood that the conductors  50  can have different shapes, including but not limited to straight lines, crenulated lines and/or wavy lines, for this technology to work. The spacing between the conductors  50  may be anywhere from 1/50 of a wavelength of the energy to be transmitted to about ½ of the wavelength of the energy to be transmitted and the width of the conductors  50  may be about ⅛ of a wavelength of the energy to be transmitted. 
   Although the curved partial reflector  20  in  FIG. 3  is represented as a circle, it shall be understood that the curved partial reflector  20  can have different shapes, including, but not limited to, square and/or rectangular shapes. 
   In one exemplary embodiment, apparatus  55  depicted in  FIG. 5  may operate as an amplifier/oscillator.  FIG. 5  depicts the array  15  of amplification devices  10  disposed on a heatsink layer  40  with a waveguide  45  coupled with the array  15 .  FIG. 5  further depicts reflector  20  rotationally disposed above the array  15  of amplification devices  10 .  FIG. 6  depicts the top view of the array  15  of amplification devices  10  with an opening  60  for the waveguide  45 . 
   By rotating the reflector  20  so as to position the conductors  50  to be parallel with the polarization of the input antenna  25  in the X direction (for example), as shown in  FIG. 7 , the apparatus  55  operates as a high power amplifier. The energy from the opening  60  of the waveguide  45  is reflected off of the conductors  50 , absorbed by the input antennas  25 , amplified by amplifier  30  and is then reradiated by the output antennas  26  in the cross polarization, in the Y direction (for example), which allows it to pass mostly unaffected through the conductors  50  that are arranged orthogonal to the output energy in the Y direction. See  FIG. 5 . 
   By rotating the reflector  20  to another position, for example as depicted in  FIG. 8 , some of the output energy will be converted into cross polarized mode, thus coupling together the inputs and outputs. If the cross polarized coupling is increased beyond a certain threshold, by rotating the reflector  20 , the array  15  of amplification devices  10  will oscillate causing the apparatus  55  to operate as an oscillator. The rotation of the reflector  20  may range from a few degrees to forty-five (45) degrees to cause the apparatus  55  to operate as an oscillator. 
   In  FIGS. 7 and 8  the reflector  20  is depicted as being translucent in order to show the array  15  of amplification devices  10  below; however, it should be understood that the reflector  20  may well be opaque and is only shown as being translucent to help depict its overall relation to the underlying structure. 
   The reflector  20  and the array  15  shown in  FIGS. 5 ,  7  and  8  and the amplification device  10  shown in  FIGS. 1 and 2  are not drawn to scale. The diameter of the reflector  20  may be twice the width of the array  15  and the size of the amplification device  10  may be about ½ of a wavelength of the energy to be transmitted. 
   In another exemplary embodiment, an apparatus  65  as depicted in  FIG. 9  may operate as an amplifier/oscillator.  FIG. 9  depicts the array  15  of amplification devices  10  disposed on a heatsink layer  40  with a reflector  20  rotationally and removably disposed above the array  15 .  FIG. 10  depicts the top view of the array  15  of amplification devices  10  without an opening for a waveguide. 
   By removing the reflector  20 , as shown in  FIG. 11 , the apparatus  65  operates as a high power amplifier. The energy, polarized in the X direction (for example), is absorbed by the input antennas  25 , amplified by amplifier  30  and is then reradiated, cross polarized in the Y direction, by the output antennas  26  in the Z direction. 
   By adding the reflector  20 , for example as depicted in  FIGS. 12 and 13 , some of the output energy will be converted into cross polarized mode, thus coupling together the inputs and outputs. If the cross polarized coupling is increased beyond a certain threshold, by rotating the reflector  20 , the array  15  of amplification devices  10  will oscillate causing the apparatus  65  to operate as an oscillator. 
   In  FIG. 13  the reflector  20  is depicted as being translucent in order to show the array  15  of amplification devices  10  below; however, it should be understood that the reflector  20  may well be opaque and is only shown as being translucent to help depict its overall relation to the underlying structure. 
   The reflector  20  and the array  15  shown in  FIGS. 9 ,  12  and  13  and the amplification device  10  shown in  FIG. 10  are not drawn to scale. The diameter of the reflector  20  may be twice the width of the array  15  and the size of the amplification device  10  may be about ½ of a wavelength of the energy to be transmitted. 
   In another exemplary embodiment, apparatus  70  as depicted in  FIG. 14  may operate as an oscillator.  FIG. 14  depicts the array  15  of amplification devices  10  disposed on a heatsink layer  40  with a reflector  20  rotationally disposed above the array  15 . 
   By rotating the reflector  20  so as to position the conductors  50  to be at an angle with the polarization of the input antenna  25  in the X direction, as shown in  FIG. 15 , the apparatus  70  operates as an oscillator. Any electrical noise in the apparatus  70  is amplified by the amplifier  30  and supplied to the output antennas  26 . The output antennas  26  output the energy which reflects off of the conductors  50 , is absorbed by the input antennas  25  causing the apparatus  70  to operate as an oscillator. 
   In  FIGS. 15 and 16  the reflector  20  is depicted as being translucent in order to show the array  15  of amplification devices  10  below; however, it should be understood that the reflector  20  may well be opaque and is only shown as being translucent to help depict its overall relation to the underlying structure. 
   The reflector  20  and the array  15  shown in  FIGS. 14 and 15  and the amplification device  10  shown in  FIG. 14  are not drawn to scale. The diameter of the reflector  20  may be twice the width of the array  15  and the size of the amplification device  10  may be about ½ of a wavelength of the energy to be transmitted. 
   The foregoing detailed description of exemplary and preferred embodiments is presented for purposes of illustration and disclosure in accordance with the requirements of the law. It is not intended to be exhaustive nor to limit the invention to the precise form(s) described, but only to enable others skilled in the art to understand how the invention may be suited for a particular use or implementation. The possibility of modifications and variations will be apparent to practitioners skilled in the art. No limitation is intended by the description of exemplary embodiments which may have included tolerances, feature dimensions, specific operating conditions, engineering specifications, or the like, and which may vary between implementations or with changes to the state of the art, and no limitation should be implied therefrom. Applicant has made this disclosure with respect to the current state of the art, but also contemplates advancements and that adaptations in the future may take into consideration of those advancements, namely in accordance with the then current state of the art. It is intended that the scope of the invention be defined by the Claims as written and equivalents as applicable. Reference to a claim element in the singular is not intended to mean “one and only one” unless explicitly so stated. Moreover, no element, component, nor method or process step in this disclosure is intended to be dedicated to the public regardless of whether the element, component, or step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. Sec. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for . . . ” and no method or process step herein is to be construed under those provisions unless the step, or steps, are expressly recited using the phrase “step(s) for . . . .”