Abstract:
A communications system for multiple aircraft in flight which provides for multi-hand simultaneous high and low frequency communications utilizing a variable geometry type antenna. The system operates simultaneously in a broadcast mode on low frequencies and in a directed mode on high frequencies.

Description:
RELATIONSHIP TO OTHER PENDING APPLICATIONS 
       [0001]    This patent application is a divisional of and claims any and all priority benefit from U.S. patent application Ser. No. 14/703,959 filed on May 5, 2015, now pending and incorporated by reference herein. 
     
    
     STATEMENT OF GOVERNMENT INTEREST 
       [0002]    The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    This invention relates to the use of a software definable pixelated patch antenna as the front end of a low to high frequency and high to low frequency translator for communications systems. 
         [0004]    There is a continuous and ongoing effort to bridge the gap between low frequency omni-directional communications systems with high-frequency Low Probability of Intercept (LPI) systems. Current translation efforts involve multiple antenna systems and are cumbersome and cannot be installed on the platforms which could gain the most use thereof. 
         [0005]    It is clearly desirable to have a system capable of operating simultaneously on both the low and high frequency bandwidths while maintaining a small overall footprint, however until recently the antenna portion of such a system was lacking. U.S. Pat. No. 8,654,034B2 to Legare for example discloses various antenna systems simultaneously capable of functioning independently on a low and high frequency. This prior art, however, is focused on the functioning of the reconfigurable portions of the antennas themselves and not their application. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0006]    It is therefore an object of the present invention to provide an apparatus that overcomes the prior art&#39;s dependency on separate fixed, non-reconfigurable antennas, each with their own independent radio system for high and low frequency applications. 
         [0007]    It is a further object of the present invention to provide an apparatus with the capability of automatically repeating and transmitting received communications on one band into the other (i.e. receiving data on a low frequency link and retransmitting it on a high frequency band). 
         [0008]    The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
         [0009]    The present invention overcomes the shortcomings of the prior art by envisaging a unique means of using the antenna systems as well as different transmit and receive equipment not provided in the prior art. The present invention utilizes a conformal pixelated patch-shaped or display type antenna, whose overall geometry has a resonant frequency at the lower frequency band (for example about 960 MHz for a square 115×115 mm) and a pixel element capable of beam steering above 5 GHz. This allows dual band use of the same antenna with the low frequency band using the entire patch (i.e., all radiating elements) in a standard manner while the high frequency band is taking advantage of the reconfigurable nature (i.e., selectable radiating elements) of these antenna types. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic diagram representation of a preferred embodiment of the present invention. 
           [0011]      FIG. 2  depicts a use of the present invention for the purposes of airborne communications. 
           [0012]      FIG. 3  is a schematic diagram depicting the various RF feeds off a pixelated patch antenna. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0013]    Referring to  FIG. 1 , the present invention, called a Multiband Communications and Repeater System (MCaRS), is composed of a reconfigurable pixelated patch or display type antenna  100  with simultaneous radio frequency (RF) transmit (Tx) and receive (Rx) signals (i.e., modes)  110  coming from both low and high frequency systems. There are multiple possible means of separating the high and low frequency RF, the means envisioned here consists of a circulator  120  with ports designed to admit only the proper low and high frequency RF  130  and  140  to the respective Rx/Tx communications systems  150  and  160 , although alternate instantiations could rely on band pass filters for this purpose as seen in  FIG. 3   290  and  310 . The received data  330  is sent to the Data Decoder/Encoder  170  which, based on requirements, determines if the data needs to be resent via the high or low frequency Rx/Tx and properly formats the data for the appropriate system  340  and  350  thus acting as a repeater. For pre-existing commercial or government radio systems (which would replace the Rx/Tx systems ISO and  160 ) the Decoder/Encoder  170  would ensure the data is properly formatted for each radio system, while also sending the data  360  to and from the I/O Adaptor  180  as necessary. The High Frequency Directional Determination system  190  accepts control signals  380  from the I/O Adaptor  180  and the separate signals  370  from the High Frequency Rx/Tx  160  to control the display antenna via the Antenna Control  220 , ensuring the proper beam shaping for the high frequency capability. 
         [0014]      FIG. 2  shows an application of the present invention as an airborne communications system. An aircraft  240  is depicted communication with two other aircraft using both low frequency modes  250  denoted by non-directionality of the radiating patterns and high frequency modes  380  denoted by highly directive radiation patterns. 
         [0015]      FIG. 3  shows how the high frequency RF  270  is fed to the adaptive portion of the antenna  260 , here shown as a pixelated patch (i.e., selectable radiating element). The entire antenna (i.e., all antenna radiating elements), meanwhile, serves to provide the antenna for the low frequency RF  280  due to inter-element coupling at low frequencies. In the instantiation shown in  FIG. 3  the high and low frequency RF are fed off separate feeds and pass through the appropriate band pass filter  290  and  310  (as an alternate embodiment to the use of a circulator  120 ) before being sent to the various Tx/Rx modules via high and low frequency I/O elements  300  and  320 . 
       DETAILED DESCRIPTION OF AN ALTERNATE EMBODIMENT 
       [0016]    An alternate embodiment would be mostly identical, however the circulator method of separating frequency bands  FIG. 1   120  would be replaced by a set of high and low frequency band pass filters similar to the method shown in  FIG. 3 . 
         [0017]    Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from, the scope or spirit of the invention as defined in the appended claims.