Abstract:
Various embodiments are described that relate to a patch antenna. Portions of a patch antenna, such as a patch antenna element and a probe feed wire can produce an impedance that is undesirable. To compensate for this, a parasitic feed pad can be aligned with the patch antenna element to create a capacitor. This capacitor produces a capacitance that negates the impedance. It can be preferred for the capacitance to be such that there is no excess capacitance and no excess impedance.

Description:
GOVERNMENT INTEREST 
       [0001]    The innovation described herein may be manufactured, used, imported, sold, and licensed by or for the Government of the United States of America without the payment of any royalty thereon or therefor. 
     
    
     BACKGROUND 
       [0002]    Communication systems can employ antennas to send information between two locations. These antennas can have preferred operating characteristics. When functioning at preferred operating characteristics, communication can be clearer and processing of data can be faster. Therefore, it can be desirable to have antennas perform with preferred operating characteristics. 
       SUMMARY 
       [0003]    In one embodiment, a system comprises a patch antenna element and a parasitic feed pad. The patch antenna element and the parasitic feed pad are parallel to one another, are stacked together, and do not touch. The patch antenna element produces an impedance and the patch antenna element and the parasitic feed pad together produce a capacitance that compensates for the impedance. 
         [0004]    In one embodiment, a system comprises a patch antenna element, a parasitic feed pad, and a probe feed wire. The probe feed wire can emit an electromagnetic field to excite the patch antenna element such that the patch antenna element is operational can be configured to not touch the patch antenna element. The patch antenna element and the parasitic feed pad can be parallel to one another, be stacked together, not touch one another, and together produces an impedance. The patch antenna element and the parasitic feed pad together produce a capacitance in series with the impedance such that a sum of the impedance with the capacitance is equal to about zero. 
         [0005]    A patch antenna production system comprising a configuration component and an output component. The configuration component can be configured to determine a parameter set for a patch antenna and the output component can be configured to cause an output of the parameter set. The patch antenna comprises a patch antenna element, a parasitic feed wire, and a parasitic feed pad. The probe feed wire does not touch the patch antenna element. The patch antenna element and the parasitic feed pad are parallel to one another, are stacked together, do not touch, and together produces an impedance. The patch antenna element and the parasitic feed pad together produce a capacitance in series with the impedance such that a sum of the impedance with the capacitance is equal to about zero. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Incorporated herein are drawings that constitute a part of the specification and illustrate embodiments of the detailed description. The detailed description will now be described further with reference to the accompanying drawings as follows: 
           [0007]      FIGS. 1 a  and 1 b    illustrate one embodiment of a system comprising a patch antenna element, a parasitic feed pad, a probe feed wire, and a ground plane; 
           [0008]      FIG. 2  illustrates one embodiment of a system comprising the patch antenna element, the parasitic feed pad, and a substrate material; 
           [0009]      FIG. 3  illustrates one embodiment of a pair of Smith charts; 
           [0010]      FIG. 4  illustrates one embodiment of a system comprising a configuration component and an output component; 
           [0011]      FIG. 5  illustrates one embodiment of a system comprising the configuration component, the output component, and a construction component; 
           [0012]      FIG. 6  illustrates one embodiment of a system comprising a processor and a computer-readable medium; 
           [0013]      FIG. 7  illustrates one embodiment of a method comprising two actions; 
           [0014]      FIG. 8  illustrates one embodiment of a method comprising two actions; 
           [0015]      FIG. 9  illustrates one embodiment of a method comprising three actions; and 
           [0016]      FIG. 10  illustrates one embodiment of a method comprising three actions. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In one embodiment, aspects disclosed herein relate to a patch antenna. The patch antenna can comprise a patch antenna element that, when excited, performs communication functions and a probe feed wire that causes the excitement. The patch antenna can have a resistance, such as 50 Ω, that is desired and this resistance can be considered a real part of the patch antenna complex input impedance. It may be desirable for patch antenna to not have an imaginary part (this can allow the antenna to have a maximum radio frequency signal that is radiated from a signal source). However, a feed probe of the patch antenna element and/or the probe feed wire can individual introduce extra inductance into the patch antenna that contribute to positive imaginary part. 
         [0018]    To counter this, an element that introduces capacitance into the patch antenna can be used. Since the patch antenna comprises the patch antenna element the patch antenna element can be leveraged to produce the capacitance. A parasitic feed patch can be aligned parallel with the patch antenna element. Together, the parasitic feed patch and the patch antenna element can form a capacitor. The configuration of the parasitic feed patch, such as size and shape, can be such that the imaginary part of the input impedance is cancelled. Therefore, the imaginary part can be a net of about zero. With this, impedance mismatching and return loss in current of the patch antenna can be compensated without lumped elements. 
         [0019]    The following includes definitions of selected terms employed herein. The definitions include various examples. The examples are not intended to be limiting. 
         [0020]    “One embodiment”, “an embodiment”, “one example”, “an example”, and so on, indicate that the embodiment(s) or example(s) can include a particular feature, structure, characteristic, property, or element, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property or element. Furthermore, repeated use of the phrase “in one embodiment” may or may not refer to the same embodiment. 
         [0021]    “Computer-readable medium”, as used herein, refers to a medium that stores signals, instructions and/or data. Examples of a computer-readable medium include, but are not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical disks, magnetic disks, and so on. Volatile media may include, for example, semiconductor memories, dynamic memory, and so on. Common forms of a computer-readable medium may include, but are not limited to, a floppy disk, a flexible disk, a hard disk, a magnetic tape, other magnetic medium, other optical medium, a Random Access Memory (RAM), a Read-Only Memory (ROM), a memory chip or card, a memory stick, and other media from which a computer, a processor or other electronic device can read. In one embodiment, the computer-readable medium is a non-transitory computer-readable medium. 
         [0022]    “Component”, as used herein, includes but is not limited to hardware, firmware, software stored on a computer-readable medium or in execution on a machine, and/or combinations of each to perform a function(s) or an action(s), and/or to cause a function or action from another component, method, and/or system. Component may include a software controlled microprocessor, a discrete component, an analog circuit, a digital circuit, a programmed logic device, a memory device containing instructions, and so on. Where multiple components are described, it may be possible to incorporate the multiple components into one physical component or conversely, where a single component is described, it may be possible to distribute that single component between multiple components. 
         [0023]    “Software”, as used herein, includes but is not limited to, one or more executable instructions stored on a computer-readable medium that cause a computer, processor, or other electronic device to perform functions, actions and/or behave in a desired manner. The instructions may be embodied in various forms including routines, algorithms, modules, methods, threads, and/or programs including separate applications or code from dynamically linked libraries. 
         [0024]      FIGS. 1 a  and 1 b    illustrate one embodiment of a system  100  comprising a patch antenna element  110 , a parasitic feed pad  120 , a probe feed wire  130 , and a ground plane  140 .  FIG. 1 a    illustrates a side view of the system  100  while  FIG. 1 b    illustrates a top-down view of the system  100 . In the top-down view, the parasitic feed pad  120  would not be visible when its profile is smaller than a profile of the patch antenna element  110 . Therefore, the parasitic feed pad  120  and the probe feed wire  130  are illustrated with a broken line to show how it can fit under the patch antenna element  110 . 
         [0025]    The parasitic antenna element  110  and the parasitic feed pad  120  can be configured to function as a system absent the probe feed wire  130  (also known as a parasitic feed probe or a parasitic probe feed) and/or the ground plane  140 . In one embodiment, a small area can exist on the same level as the antenna element  110 . This area can be isolated from the antenna element  110 , by way of small gap between the area and the antenna element  110 . This small area can function to excite the antenna element  110  can be of a square shape, rectangular shape, circle shape, or other shape. 
         [0026]    The patch antenna element  110  and the parasitic feed pad  120  and/or the ground plane  140  can be parallel to one another and stacked together. This stacking can be such that the patch antenna element  110  and the parasitic feed pad  120  and/or ground plane  140  do not touch. In one example, air can separate the patch antenna element  110  from the parasitic feed pad  120  and/or the ground plane  140 . 
         [0027]    When the system  100  is operational, the patch antenna element  110  can produce a reactance (by way of inductance). It may be desirable for a sum of the impedance and capacitance of the system  100  to be equal to about zero. In view of this, the patch antenna element  110  and the parasitic feed pad  120  can together produce a capacitance that compensates for the impedance of the patch antenna element  110 . To perform this compensation, the patch antenna element  110  and the parasitic feed pad  120  can form a capacitor. This compensation can completely compensate such that a total series inductance and capacitance is near about zero. 
         [0028]    Inductance compensation can be for the system  100 . In one example, the probe feed wire  130  produces its own impedance—additional to impedance of the patch antenna element  110  caused from inductance. The configuration of the patch antenna element  110  and the parasitic feed pad  120  together can be such that a capacitance is produced to negate the inductance of the patch antenna element  110  and the probe feed wire  130  (and other impedance of the system  100 ). 
         [0029]    The system  100  can be configured such that the probe feed wire  130  does not touch the patch antenna element  110 . In one example, the probe feed wire  130  terminates at the parasitic feed pad  120 . In another example, the probe feed wire  130  passes through the parasitic feed pad  120  and terminates beyond the parasitic feed pad  120 . With this, the patch antenna element  110  can have an opening through which the probe feed wire  130  passes. The parasitic feed pad  120  can be, in one embodiment, an orthogonal circular flat pad to the patch antenna element  110 . 
         [0030]    The probe feed wire  130  can emit an electromagnetic field and this electromagnetic field can excite the patch antenna element  110  (e.g., the probe feed wire  130  can parasitically feed the patch antenna element  110 ). The excitement can cause the patch antenna element  110  to be operational (e.g., function with a current produced from the electromagnetic field). Being operational can include allowing the system  100 , which functions as an antenna, such as to communicate with another antenna. 
         [0031]    To emit the electromagnetic field, the probe feed wire  130  can be supplied with a current. This supply can come from a coaxial cable and the probe feed wire  130 , on an end opposite from the end approaching the patch antenna element  110 , can have a connector to connect with the coaxial cable that supplies current from a current source. If the impedance is not compensated, then an impedance mismatch occurs between the current source and the system  100 . Keeping the impedance mismatch results in increased return loss and a lower percentage of power radiated by the system  100  by way of the patch antenna element  110 . 
         [0032]    While  FIG. 1 b    illustrates the patch antenna element  110  as being a square, various other shapes can be used. In one example, a desired polarization type can influence the shape of the patch antenna element  110 . For linear polarization, the patch antenna element  110  can be, for example, square, rectangular, or a circle. For circular polarization, the patch antenna element can be, for example, a hexagon. In another example, multiple layers can be used (e.g., multiple layers of the parasitic feed pad  120 ). 
         [0033]      FIG. 2  illustrates one embodiment of a system  200  comprising the patch antenna element  110 , the parasitic feed pad  120 , and a substrate material  210 . While air can separate the patch antenna element  110  from the parasitic feed antenna  120 , these can also be separated by the substrate material  210 . In one example, the patch antenna element  110  can be coupled to a first side of the substrate material  210 . Likewise, the parasitic feed pad  120  can be coupled to a second side of the substrate material  210  that is opposite the first side of the substrate material. 
         [0034]    In one embodiment, the substrate material  210  is used to secure the probe feed wire  130  of  FIG. 1  (collectively  FIGS. 1 a  and 1 b   ). The parasitic feed pad  120  can have a hole. The probe feed wire  130  of  FIG. 1  can pass through the hold and attach to the substrate material  210 . Attachment can occur at the end of the probe feed wire  130  or elsewhere on the probe feed wire  130  of  FIG. 1 . The patch antenna element  130  can have a physical separation and the probe feed wire  130  can pass through the physical separation as well as the parasitic feed pad  120  while being attached to the substrate material  210  or elsewhere that is not the patch antenna element (e.g., when the substrate material is not used). 
         [0035]    The substrate material  210  can be a printed circuit board material with copper on each side of the board and an object of a certain thickness in between both layers of copper. The patch antenna element  110  can be etched or milled onto one side of the copper board and likewise the parasitic feed pad can  120  be on the opposite side of the board. The thickness of the board is selected such that it creates the desired separation distance between the patch antenna element  110  and the parasitic feed pad  120 . Substrate material thickness has great influence on the capacitance introduced to the system  200  as well as the ability for the parasitic feed pad  120  to couple energy onto the patch antenna element  110  (e.g., radiating patch element). The substrate thickness can be tightly controlled since the manufacturing tolerance of commercial printed circuit boards is typically extremely reliable. Once both sides of the printed circuit board are etched or milled, the probe wire feed  130  of  FIG. 1  can be solder connected with the parasitic feed pad  120  or otherwise fixed. Connection can occur such that the probe feed wire  130  of  FIG. 1  is orthogonal to the parasitic feed pad  120  and the patch antenna element  110  is parallel to the ground plane  140  of  FIG. 1 . 
         [0036]      FIG. 3  illustrates one embodiment of a pair of Smith charts  310  and  320 . The Smith chart  310  can illustrate an impedance curve sample without introduction of the parasitic feed pad  120  of  FIG. 1 . The Smith chart  320  can illustrate an impedance curve sample with introduction of the parasitic feed pad  120  of  FIG. 1  and in turn introduction of the capacitor. To put another way, the Smith chart  320  can illustrate operation of the system  100  of  FIG. 1 . The Smith charts  310 - 320  shows with the curve at position A that the system  100  of  FIG. 1  minus the parasitic feed pad  120  can include a real portion (resistance) and an imaginary portion (net inductance or capacitance). By introduction of the capacitor the curve can move to position B such that the imaginary portion is reduced to about zero. 
         [0037]      FIG. 4  illustrates one embodiment of a system  400  comprising a configuration component  410  and an output component  420 . The configuration component  410  can be configured to determine a parameter set for a patch antenna (e.g., the system  100  of FIG.  1 ) and the output component  420  can be configured to cause an output of the parameter set. The patch antenna can comprises the patch antenna element  110  of  FIG. 1 , the parasitic feed wire  130  of  FIG. 1 , and the parasitic feed pad  120  of  FIG. 1 . The patch antenna element  110  and the probe feed wire  130 , both of  FIG. 1 , can produce an impedance (independently produce an impedance) and not touch one another. The patch antenna element  110  and the parasitic feed pad  120 , both of  FIG. 1 , can be parallel to one another, stacked together, not touch, and together produce a capacitance in series with the impedance such that a sum of the impedance with the capacitance is equal to about zero. 
         [0038]    In one embodiment the patch antenna comprises the substrate material  210  of  FIG. 2 . The substrate material  210  of  FIG. 2  can separate the patch antenna element  110  of  FIG. 1  from the parasitic feed pad  120  of  FIG. 1 . The parameter set can comprise a thickness of the substrate material  210  if  FIG. 2 . Another example of a parameter of the parameter set can be a shape of the patch antenna element  110  of  FIG. 1  that influences a polarization type of the patch antenna. 
         [0039]    Additionally, the parameter set can have information regard the parasitic feed pad  120  of  FIG. 1 . With this, the configuration component  410  can receive an operating frequency of the antenna (e.g., the system  100  of  FIG. 1 ) and an impedance of the system  100  of  FIG. 1 . This can be used to determine a radius of the parasitic feed pad  120  of  FIG. 1  and a distance between the parasitic feed pad  120  and the patch antenna element  110 , both of  FIG. 1 , so that the impedance is compensated without excess capacitance. 
         [0040]    The system  400  (e.g., patch antenna production system) can receive an input, such as by way of an interface. The input can be from a user and detail information on the patch antenna. Examples of the input can be size of the patent antenna element  110  of  FIG. 1 , length of the probe feed wire  130  of  FIG. 1 , and/or an operational frequency of the patch antenna, Based on this information, the parameter set for the patch antenna can be determined by the configuration component. In one example, the input can be analyzed (e.g. entered into an algorithm) and based on this analysis the parameter set can be determined. With this, the expected impedance of the patch antenna can be calculated and based on this the thickness of the substrate material  210  of  FIG. 2  (and in turn distance between the patch antenna element  110  and the parasitic feed pad  120  both of  FIG. 1 ) and/or the makeup (e.g., size and/or shape) of the parasitic feed pad  120  of  FIG. 2  can be calculated. This calculation can be such that the impedance is compensated. 
         [0041]      FIG. 5  illustrates one embodiment of a system  500  comprising the configuration component  410 , the output component  420 , and a construction component  510 . The construction component  510  can be configured to access the parameter set from the output and construct the patch antenna in accordance with the parameter set. Examples of construction can be cutting the substrate material  210  of  FIG. 2 , selecting the substrate material  210  of  FIG. 2 , affixing the patch antenna element  110  and the parasitic feed pad  120  both of  FIG. 1  to the substrate material  210  of  FIG. 2 , and placing and affixing the probe feed wire  130  of  FIG. 1 . 
         [0042]    Since exact compensation for impedance may be difficult to achieve, the construction component  510  can make modifications as appropriate. In one example, the parameter set can call for the substrate material  210  to be of x thickness, but available substrate materials may not include one of x thickness. Therefore, the construction component  510  can substitute for a substrate material closest to x thickness. However, distance between the patch antenna element  110  and the parasitic feed pad  120 , both of  FIG. 1 , can be very small with a very low tolerance for variation and therefore the construction component  510  can decide to take alternative action (e.g., modify available substrate pieces). 
         [0043]    The construction component  510  can function outside of the system  500 . In one example, the system  400  of  FIG. 4  transmits, by way of the output component  420  of  FIG. 4 , the parameter set to construction component  510 . Based on this, the construction component  510  can produce a plurality of patch antenna in view of the parameter set (e.g., create a production line). In one embodiment, the construction component  510  builds the patch antennas while calculations on how the antennas should be built in view of the parameter set is produced elsewhere (e.g., by a calculation component that is part of the configuration component  410  and results are part of the parameter set). With this, the parameter set can be operational parameters (e.g., impedance is at y value) or functional parameters (e.g., the distance between the patch antenna element  110  of  FIG. 1  and the parasitic feed pad  120  of  FIG. 1  should by z centimeters). 
         [0044]      FIG. 6  illustrates one embodiment of a system  600  comprising a processor  610  (e.g., a general purpose processor or a processor specifically designed for performing functionality disclosed herein) and a computer-readable medium  620  (e.g., non-transitory computer-readable medium). In one embodiment, the computer-readable medium  620  is communicatively coupled to the processor  610  and stores a command set executable by the processor  610  to facilitate operation of at least one component disclosed herein (e.g., the configuration component  410  of  FIG. 4 ). In one embodiment, at least one component disclosed herein (e.g., the output component  420  of  FIG. 4 ) can be implemented, at least in part, by way of non-software, such as implemented as hardware by way of the system  600 . In one embodiment, the computer-readable medium  620  is configured to store processor-executable instructions that when executed by the processor  610  cause the processor  610  to perform a method disclosed herein (e.g., the methods  700 - 1000  addressed below). 
         [0045]      FIG. 7  illustrates one embodiment of a method  700  comprising two actions  710 - 720 . The method  700  can be for operation of, and performed by, the probe feed wire  130  of  FIG. 1 . At  710  a current can be received. In one embodiment, the probe feed wire  130  of  FIG. 1  comprises a connector that is configured to connect with a coaxial cable. The coaxial cable supplies the current to the probe feed wire  130  of  FIG. 1  that the probe feed wire  130  of  FIG. 1  receives. At  720  the received current can be used to produce the electromagnetic field. 
         [0046]      FIG. 8  illustrates one embodiment of a method  800  comprising two actions  810 - 820 . The method  800  can be for operation of, and performed by, the patch antenna element  110  of  FIG. 1 . At  810  an electromagnetic field can be experienced, such as the one produced by way of  720  of  FIG. 7 . Based on this the experience, at  820  a response to the electromagnetic field can occur. This response can cause the patch antenna element  110  of  FIG. 1  to be operational. 
         [0047]      FIG. 9  illustrates one embodiment of a method  900  comprising three actions  910 - 930 . The method  900  can be for operation of, and performed by, the system  100  of  FIG. 1 . At  910  impedance from the patch antenna element  110  of  FIG. 1  can be experienced while at  920  impedance from the probe feed wire  130  of  FIG. 1  can be experienced. At  930 , compensation can occur for at least part of the impedance. This compensation can be performed by a capacitor formed by the antenna element  110  and parasitic feed pad  120 , both of  FIG. 1 . 
         [0048]      FIG. 10  illustrates one embodiment of a method  1000  comprising three actions  1010 - 1030 . The method  1000  can be for operation of, and performed by, the system  500  of  FIG. 5 . At  1010  input data can be received, such as desired performance for an antenna. Based on this input data a parameter set for the antenna can be determined at  1020 . Based on this parameter set, at  1030  the antenna can be constructed. 
         [0049]    While the methods disclosed herein are shown and described as a series of blocks, it is to be appreciated by one of ordinary skill in the art that the methods are not restricted by the order of the blocks, as some blocks can take place in different orders. Similarly, a block can operate concurrently with at least one other block. 
         [0050]    Aspects disclosed herein can be used, for example, in the fields of electromagnetics, radio frequency engineering, and antenna design. Multiple benefits exist for practicing aspects disclosed herein. One benefit is that aspects provide an ability to match the impedance of the system  100  of  FIG. 1  by adding a series capacitance, thus vastly reducing the negative impacts of the inductance introduced. Another benefit is that the series capacitance introduced to the system is done so without adding an additional component of a capacitor element, which eliminates further cost and system fabrication.