Abstract:
A Variable Height/Thickness Ratio Tapered Slot Antenna For Matching Impedance and Power Handling (NC#98542). The apparatus includes a tapered slot antenna having a gap height and a thickness. The tapered slot antenna includes a first antenna element comprising conductive material, configured to receive and transmit RF signals and a second antenna element comprising conductive material, operatively coupled to said first antenna element, configured to receive and transmit RF signals. A correlation between said gap height and said thickness can be represented by an equation.

Description:
FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
   This invention (Navy Case No. 98542) is assigned to the United States Government and is available for licensing for commercial purposes. Licensing and technical inquiries may be directed to the Office of Research and Technical Applications, Space and Naval Warfare Systems Center, San Diego, Code 2112, San Diego, Calif., 92152; voice (619) 553-2778; email T2@spawar.navy.mil. Reference Navy Case Number 98542. 

   CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. Pat. No. 7,009,572, issued on Mar. 7, 2006, entitled “Tapered Slot Antenna”, by Rob Horner et al., Navy Case No. 96507, which is hereby incorporated by reference in its entirety herein for its teachings on antennas. This application is also related to U.S. Pat. No. 7,148,855, issued on Dec. 12, 2006, entitled “Concave Tapered Slot Antenna”, by Rob Horner et al., Navy Case No. 96109, which is hereby incorporated by reference in its entirety herein for its teachings on antennas. 
   BACKGROUND OF THE INVENTION 
   The present invention is generally in the field of antennas. 
   Typical tapered slot antennas (TSA) are designed with power handling limitations and complex impedance matching networks. One method of increasing power capacity and operating bandwidth of a TSA is to increase the thickness of the TSA. However, increasing thickness produces a change in impedance. 
   A need exists for tapered slot antennas having higher power handling capability and less complex impedance matching network. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a side view of a variable height/thickness ratio tapered slot antenna. 
       FIG. 1B  is a front view of a variable height/thickness ratio tapered slot antenna. 
       FIG. 2  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna. 
       FIG. 3  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna. 
       FIG. 4  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna. 
       FIG. 5  is a flowchart of an exemplary method of manufacturing one embodiment of a variable height/thickness ratio tapered slot antenna. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is directed to Variable Height/Thickness Ratio Tapered Slot Antenna For Matching Impedance and Power Handling. 
   DEFINITIONS 
   The following acronyms and definitions are used herein: 
   Acronym(s): 
   I/O—Input/Output 
   RF—radio frequency 
   TSA—Tapered Slot Antenna 
   VHTR—Variable Height/Thickness Ratio 
   Definition(s): 
   Height/Thickness ratio—the ratio between the gap height and thickness of a TSA 
   The variable height/thickness ratio (VHTR) tapered slot antenna for matching impedance includes a TSA having a gap height correlated to a thickness (i.e., width) to insure a matched impedance. The correlation between gap height and thickness to insure a matched impedance is based on an equation. The VHTR TSA for impedance matching includes an antenna pair having a gap height and a thickness. 
     FIG. 1A  is a side view of one embodiment of a VHTR tapered slot antenna for impedance matching. As shown in  FIG. 1A , VHTR TSA for impedance matching  100  includes an antenna pair (i.e., antenna element  110  and antenna element  120 ) comprising conductive material. The antenna pair of VHTR TSA for impedance matching  100  has gap height  194 , a feed end and a launch end. The feed end of the antenna pair corresponds to the portion of the antenna pair that is proximate to axis  140  (represented by dashed line K-K on  FIG. 1A ). The feed end receives and transmits signals. The launch end of the antenna pair corresponds to the portion of the antenna pair that is proximate to axis  146  (represented by dashed line N-N on FIG.  1 A). Note that the launch end only denotes a location on the antenna pair versus an actual launch point of a particular frequency. Antenna element (AE)  110  has lateral edge  114 , which corresponds to the portion of AE  110  that is proximate to axis  142  (represented by dashed line L-L on  FIG. 1A ). Antenna element  120  has lateral edge  124 , which corresponds to the portion of AE  120  that is proximate to axis  144  (represented by dashed line M-M on  FIG. 1A ). 
   TSA length  154  of VHTR TSA for impedance matching  100  is defined as the distance between the feed end (proximate to axis  140 ) and the launch end (proximate to axis  146 ). TSA height  162  of VHTR TSA for impedance matching  100  is defined as the distance between the lateral edges of the antenna pair (i.e., the distance between lateral edge  114  and lateral edge  124 ) (i.e., the distance between axis  142  and axis  144 ). 
   In one embodiment, TSA antenna elements  110 ,  120  have curvatures that can each be represented by the following Equation 1:
 
 Y ( x )= a ( e   bx −1);  (Equation 1)
         where, a and b are parameters selected to produce a desired curvature. In one embodiment, parameters “a” and “b” are approximately equal to 0.2801 and 0.1028, respectively.       

     FIG. 1B  is a front view of one embodiment of a typical TSA. VHTR TSA for impedance matching  100  of  FIG. 1B  is substantially similar to VHTR TSA for impedance matching  100  of  FIG. 1A , and thus, similar components are not described again in detail hereinbelow. As shown in  FIG. 1B , VHTR TSA for impedance matching  100  includes an antenna pair (i.e., antenna element  110 , antenna element  120 ). The antenna pair of VHTR TSA for impedance matching  100  has gap height  194 . VHTR TSA for impedance matching  100  has TSA thickness  172 . 
   Equation 2 represents the correlation between gap height and TSA thickness (i.e., TSA width) for the VHTR TSA for impedance matching. 
                   h   =       w   ×     z   0     ×       e   r           V   ×   π         ;           (     EQUATION   ⁢           ⁢   2     )               
where
         h=gap height   w=TSA thickness   z 0 =characteristic impedance   e r =dielectric constant of dielectric spacing material.   V=a constant having a value greater than or equal to 15 and less than or equal to 100. In one embodiment, V=44.   π=ratio of a circle&#39;s circumference to its diameter
 
As shown above in Equation 2, gap height equals the product of TSA thickness multiplied by characteristic impedance multiplied by the square root of the dielectric constant of dielectric spacing material divided by the product of V multiplied by pi. In one embodiment, V=44. In one embodiment, the dielectric spacing material comprises air. In one embodiment, the dielectric spacing material comprises Teflon®.
       
   In one embodiment, gap height equals 0.135 inches for a VHTR TSA for impedance matching having a TSA thickness of 0.375 inches, a characteristic impedance of 50 ohms, V equal to 44 and a dielectric constant of dielectric spacing material of 1.000536. In one embodiment, gap height equals 0.045 inches for a VHTR TSA for impedance matching having a TSA thickness of 0.125 inches, a characteristic impedance of 50 ohms, V equal to 44 and a dielectric constant of dielectric spacing material of 1.000536. In one embodiment called a Teflon® dielectric spacer embodiment, gap height equals 0.192 inches for a VHTR TSA for impedance matching having a TSA thickness of 0.375 inches, a characteristic impedance of 50 ohms, V equal to 44 and a dielectric constant of dielectric spacing material of 2. 
     FIG. 2  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna for impedance matching. VHTR TSA for impedance matching  200  of  FIG. 2  is substantially similar to VHTR TSA for impedance matching  100  of  FIG. 1B , and thus, similar components are not described again in detail hereinbelow. As shown in  FIG. 2 , VHTR TSA for impedance matching  200  includes an antenna pair (i.e., antenna element  210  and antenna element  220 ) comprising conductive material. The antenna pair of VHTR TSA for impedance matching  200  has antenna element height  262 , gap height  294  and TSA thickness  272 . Antenna element height  262  represents the height of antenna element  210 , which is approximately equal to the height of antenna element  220 . VHTR TSA for impedance matching  200  has fixed dimensions that allow for a certain power handling capacity. In one embodiment, the fixed dimensions allow for a characteristic impedance (z 0 ) of 50 ohms. 
     FIG. 3  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna for impedance matching. VHTR TSA for impedance matching  300  of  FIG. 3  is substantially similar to VHTR TSA for impedance matching  100  of  FIG. 1B , and thus, similar components are not described again in detail hereinbelow. As shown in  FIG. 3 , VHTR TSA for impedance matching  300  includes an antenna pair (i.e., antenna element  310  and antenna element  320 ) comprising conductive material. The antenna pair of VHTR TSA for impedance matching  300  has antenna element height  362 , gap height  394  and TSA thickness  372 . Antenna element height  362  (which may be equal to antenna element height  262  of  FIG. 2 ) represents the height of antenna element  310 , which is approximately equal to the height of antenna element  320 . VHTR TSA for impedance matching  300  has fixed dimensions that allow for a certain power handling capacity. In one embodiment, the fixed dimensions allow for a characteristic impedance (z 0 ) of 50 ohms. VHTR TSA for impedance matching  300  of  FIG. 3  has higher power handling capacity than VHTR TSA for impedance matching  200  of  FIG. 2  because VHTR TSA for impedance matching  300  has a greater TSA thickness  372  compared to TSA thickness  272  of VHTR TSA for impedance matching  200 . Thus and according to Equation 2, gap height  394  is greater than gap height  294 . 
     FIG. 4  is a front view of one embodiment of a variable height/thickness ratio tapered slot antenna for impedance matching. VHTR TSA for impedance matching  400  of  FIG. 4  is substantially similar to VHTR TSA for impedance matching  100  of  FIG. 1B , and thus, similar components are not described again in detail hereinbelow. As shown in  FIG. 4 , VHTR TSA for impedance matching  400  includes an antenna pair (i.e., antenna element  410  and antenna element  420 ) comprising conductive material. The antenna pair of VHTR TSA for impedance matching  400  has antenna element height  462 , gap height  494  and TSA thickness  472 . Antenna element height  462  represents the height of antenna element  410 , which is approximately equal to the height of antenna element  420 . VHTR TSA for impedance matching  400  has higher power handling capacity than VHTR TSA for impedance matching  300  of  FIG. 3  because VHTR TSA for impedance matching  400  has a greater TSA thickness  472  compared to TSA thickness  372  of VHTR TSA for impedance matching  300 . Thus and according to Equation 2, gap height  494  is greater than gap height  394 . 
     FIG. 5  is a flowchart illustrating an exemplary process to implement an exemplary VHTR TSA for impedance matching. While boxes  510  through  530  shown in flowchart  500  are sufficient to describe one embodiment of an exemplary TSACA, other embodiments of the TSACA may utilize procedures different from those shown in flowchart  500 .