Frequency-scan traveling wave antenna

Abstract

A frequency-scan traveling wave antenna receives radio frequency (RF) energy at an input port, passes the energy through a quarter wave transformer to a first radiator element in an array of radiator elements, each pair of radiator elements being connected by a respective delay line. Each radiator element includes an input port of known characteristic impedance connected to an impedance matching section which compensates for that element's radiated power. Each radiator element has an output port with a section of transmission line disposed between a main radiator section of said radiator element and said output port, and impedance matched to the output port. In one embodiment, each delay line includes a plurality of delay line sections, with adjacent delay line sections being mutually perpendicular. In a second embodiment, each delay line includes a plurality of delay line sections disposed in meandering form.

What is claimed is:  
     
       1. A frequency-scan traveling wave antenna, comprising a plurality of paired radiator elements, each pair of radiator elements being connected by a respective delay line; 
       each of said radiator elements comprising an input port, a main radiator, and impedance matching means connected between said input port and said main radiator for compensating for radiated power in said radiator elements, and for matching an input impedance of said radiator elements to an output impedance of said radiator elements.  
     
     
       2. The frequency-scan traveling wave antenna of  claim 1 , further comprising a quarter-wave transformer connected to said input port of a first one of said radiator elements. 
     
     
       3. The frequency-scan traveling wave antenna of  claim 1 , wherein each of said radiator elements includes an output port and a section of transmission line connected between said main radiator and said output port, said section of transmission line being impedance matched to said output port. 
     
     
       4. The frequency-scan traveling wave antenna of  claim 3 , wherein said section of transmission line sets an electrical length of said radiator elements to one full wavelength. 
     
     
       5. The frequency-scan traveling wave antenna of  claim 1 , wherein said plurality of radiator elements and said delay line disposed between respective pairs of said radiator elements form a geometrically symmetric arrangement, thereby balancing stray radiation and minimizing an amount of degradation of a beam pattern and side lobe levels due to radiation from said delay line between said radiator elements. 
     
     
       6. The frequency-scan traveling wave antenna of  claim 1 , wherein each of said delay line comprises an input port, an output port, and a plurality of transmission line sections extending between said input port and said output port, said plurality of transmission line sections having uniform impedance. 
     
     
       7. The frequency-scan traveling wave antenna of  claim 6 , wherein each of said transmission line of each of said delay line is connected to an adjacent transmission line section by a mitered corner so as to maintain uniform impedance along each of said delay line. 
     
     
       8. The frequency-scan traveling wave antenna of  claim 1 , wherein each of said delay line has the same electrical length. 
     
     
       9. The frequency-scan traveling wave antenna of  claim 8 , wherein each of said delay line has an electrical length equal to one of the series (3/2, 5/2, 7/2, ...) wavelengths at a center frequency of operation. 
     
     
       10. The frequency-scan traveling wave antenna of  claim 1 , wherein an electrical phase between the center of each respective pair of radiator elements is one of the series (N+1/2) wavelengths for positive integer N. 
     
     
       11. The frequency-scan traveling wave antenna of  claim 1 , wherein each of said delay line is meandered to achieve better packing density. 
     
     
       12. The frequency-scan traveling wave antenna of  claim 1 , wherein a spacing between the center of adjacent radiators is no greater than 1.5 wavelengths at a center design frequency.