Abstract:
The present invention is a method and system for using a 3D printer for printing various tunable antennas. In one embodiment, and exponent antenna is created by printing a board using a 3D printer in combination with vacuum metallization to create the antenna and provide engineered break points for adjusting the printed antenna for the most effective gain. In another embodiment, a spiral cavity backed antenna is printed using a combination of a 3D printer and vacuum metallization. In a third embodiment, a horn antenna is printed using a combination of a 3D printer engineered break points for adjustment and a hinged version with an actuator creating a new antenna.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application Ser. No. 61/903,357, entitled “System and Method for Printing Tunable Antennas”, filed on 12 Nov. 2013. The benefit under 35 USC §119e of the U.S. provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference. 
     
    
     FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       SEQUENCE LISTING OR PROGRAM 
       [0003]    Not Applicable cl TECHNICAL FIELD OF THE INVENTION 
         [0004]    The present invention uses rapid prototyping using 3D printers in the battlefield whereby operators can print readily tunable antennas for use in various battlefield environments in combination with various existing or printed components to make or repair equipment in the field or theater of battle. 
       BACKGROUND OF THE INVENTION 
       [0005]    Device Frequency Interference (RFI) can be described as any unwanted device frequency signal, which interferes with another, desired signal. This can show up as an annoying popping or crackle on a loud-speaker, unwanted pulses, marks on a sounder paper, or spots on a radar screen. 
         [0006]    There are two ways for the noises to enter a device via the antenna. They can be conducted along the power leads and other wiring into the device, or they can be radiated from the noise source and its wiring into the device&#39;s antenna system, and then into the device. 
         [0007]    Filtering the power wiring into the device can eliminate conducted interference. Most equipment has adequate filtering built in to eliminate conducted interference, but further or specific tuning of an antenna is difficult and follows no set pattern of instruction given the variable sources. 
         [0008]    Radiated interference is the most serious problem normally encountered. Many device antenna systems and receivers have been designed for reception of very weak signals. Unfortunately the receiver cannot discriminate between these weak signals and random noise if both are on the same frequency, and if the noise has comparable strength to the required signal, then the signal is completely buried in the noise. 
         [0009]    Radiated noise is caused by any abrupt change in current flowing through a conductor. 
         [0010]    Current flowing creates a magnetic field around the conductor. When this current is changed this causes a change in the magnetic field. The changing magnetic field travels as an electro-magnetic wave for some distance from the conductor, and it is this traveling field which is radiated to the antenna. 
         [0011]    There are three basic methods of reducing RFI. The first is to prevent the device interference from reaching the antenna by shielding. If the noise source is totally enclosed in a metal can, then the noise is contained and cannot reach the antenna. 
         [0012]    The second and more practical method of noise suppression is to eliminate the noise at the source. This is achieved by installing filtering or smoothing circuits across the noise producing device or contacts. A capacitor across a contact slows down the rapid change in current when the contact is opened. The slowed change in current through the conductors results in a weaker magnetic field around the conductor and therefore less radiated interference. The slowed change in current through the conductors results in a weaker magnetic field around the conductor and therefore less radiated interference. 
         [0013]    The third important part of noise suppression is bonding. Bonding or grounding should provide a low resistance path to ground for any device frequency noise which is present. This path ensures that the noise is conducted away to ground instead of being radiated. Moreover, there always is interest either by the DoD or by commercial entities to change the beam shape of the antenna to better transmit to the receiver to change the emission frequency to accommodate the mission or application. In both cases, this tuning can be achieved using the same procedure as described in this invention. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention is a method and system for using a 3D printer for printing various tunable antennas. In one embodiment, and exponent antenna is created by printing a board using a 3D printer in combination with vacuum metallization or conductive polymers (or other non polymer material) to create the antenna and provide engineered break points for adjusting the printed antenna for the most effective gain, beam-shape and frequency. In another embodiment, a spiral cavity backed antenna is printed using a combination of a 3D printer and vacuum metallization. In a third embodiment, a horn antenna is printed using a combination of a 3D printer engineered break points for adjustment and a hinged version with an actuator creating a new antenna. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated herein an form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
           [0016]      FIG. 1  is an log-periodic antenna illustrating one embodiment of the present invention; 
           [0017]      FIG. 2  is an example of a spiral cavity backed antenna illustrating one embodiment of the present invention; and 
           [0018]      FIG. 3  is an example of a various antenna horn shapes. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    In the following detailed description of the invention of exemplary embodiments of the invention, reference is made to the accompanying drawings (where like numbers represent like elements), which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, but other embodiments may be utilized and logical, mechanical, electrical, and other changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
         [0020]    In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known structures and techniques known to one of ordinary skill in the art have not been shown in detail in order not to obscure the invention. Referring to the figures, it is possible to see the various major elements constituting the apparatus of the present invention. 
         [0021]    Now referring to  FIG. 1 , an log-periodic antenna illustrates one embodiment of the present invention. In this embodiment, the antenna is manufactured using a 3D printer and the path is created by metal vacuumization. Currently, tuning of such antenna is done by scratching the conductive material off at various locations and distances on the antenna surface. The present invention teaches a method for printing such antenna and including one or more of tabs and break points molded into the plastic surface that can easily be broken off as shown by elements A and B of  FIG. 1 . The other method for tuning is by embedding scratch off points for the soldier to scratch off the conductive element. 
         [0022]    By providing break points, tuning or adjustments are made much more easily to break a solid surface, which can result in inaccurate breaks and a ruined board. By labeling the break locations, a non-technical operator can be instructed to change an antenna to provide the desired functionality. 
         [0023]    Additionally, one or more ink printed markings indicating where to cut with a razor the electric trace may also be provided. The markings or break points taught by the present invention allow the use of an Xacto knife or razor blade for tuning the antenna by providing the locations of known points resulting in anticipated adjustments to the gain when the conductive surface is altered. 
         [0024]    In another embodiment, an actuator embedded or attached to the plastic/rubber that distorts the plastic and/or traces can be used to change the characteristics of the antenna. 
         [0025]    Additionally, during the printing of a board, capacitors can be included and printed on the board. The location of capacitors on such an antenna has known, specific effects. By printing an antenna with capacitors, tuning can quickly and effectively be done for a variety of desired wavelengths by merely snapping off or breaking the capacitor line using designed break points or a simple knife to scrape off the dielectric constant. Thus, the process can be made manually in the field or done as part of the printing process. 
         [0026]    As part of the printing process, the ends, lines, and additional spiral tuning lines can be created on the printed board to enable additional manual adjustment if the desired or automatic adjustment produces a less than desirable result. 
         [0027]    A library can be provided for the 3D printer just for various antennas and various scales of antennas as the scale or size of the antenna effects the changes necessary to effectuate the desired result in the antenna. The database can provide a parametric which allows the user to selected between performance trade-offs of various options or designs. Then, when the desired design is selected, the selected design can be readily printed by the 3D printer in the field with automatic adjustments and optional manual adjustments once the antenna is measured. Adjustments are typically based on the antenna&#39;s spectrum and gain. 
         [0028]    Now referring to  FIG. 2 , a spiral cavity backed antenna is shown. It is shaped as a two-arm spiral, but more arms may be used. Spiral antennas belong to the class of frequency independent antennas which operate over a wide range of frequencies. Polarization, radiation pattern, and impedance of such antennas remain unchanged over large bandwidth. Such antennas are inherently circularly polarized with low gain and are extremely difficult to manufacture. 
         [0029]    Now referring to  FIG. 3 , a variety of horn antennas are shown. In this embodiment the present invention is uses a 3D printer to print each component of the horn antenna. A horn antenna provides a gradual transition structure to match the impedance of a tube to the impedance of free space, enabling the waves from the tube to radiate efficiently into space. If a simple open-ended waveguide is used as an antenna, without the horn, the sudden end of the conductive walls causes an abrupt impedance change at the aperture, from the wave impedance in the waveguide to the impedance of free space. 
         [0030]    To improve these poor characteristics, the ends of the waveguide are flared out to form a horn. The taper of the horn changes the impedance gradually along the horn&#39;s length. This acts like an impedance matching transformer, allowing most of the wave energy to radiate out the end of the horn into space, with minimal reflection. The taper functions similarly to a tapered transmission line, or an optical medium with a smoothly-varying refractive index. In addition, the wide aperture of the horn projects the waves in a narrow beam. 
         [0031]    The 3D printer of the present invention would be used to create the taper of the horn and all components to assemble the horn. In particular the printing of long channels sometimes desirable in horns is not encumbered by milling restrictions. A parametric database as previously disclosed for use with the other antenna embodiments would also be used so that a user could review the various options and tradeoff of available designs to best fit their need. In this manner an automatically optimized device can be printed in one or more component parts and assembled. Additionally, the parts, such as the waveguides and throat can be printed with break points located on their surfaces so that manual adjustments can be made to adjust the lobes. 
         [0032]    Trying to mill long horns is extremely difficult and expensive due to the long bit length needed. Currently manufacturers mill them in sections/pieces to make one long horn. This results in seams where the horn sections are connected. These seams create undesirable beam effects. The 3D printing system and method of the present invention allows the long cavity/channels of the horn to be created without seams or other beam/signal interrupters. 
         [0033]    In another embodiment, a hinged version can be printed using a 3D printer in rubber instead of plastic, in such a manner that an actuator can provide adjustments to the shape and size of the waveguide. 
         [0034]    Thus, it is appreciated that the optimum dimensional relationships for the parts of the invention, to include variation in size, materials, shape, form, function, and manner of operation, assembly and use, are deemed readily apparent and obvious to one of ordinary skill in the art, and all equivalent relationships to those illustrated in the drawings and described in the above description are intended to be encompassed by the present invention. 
         [0035]    Furthermore, other areas of art may benefit from this method and adjustments to the design are anticipated. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.