Phased array antenna system including a coplanar waveguide feed arrangement

• US 5,694,134 A
• Filed: 01/14/1994
• Issued: 12/02/1997
• Est. Priority Date: 12/01/1992
• Status: Expired due to Fees

• Current Assignee: Robert M. Yandrofski, Y. Development, LLC
• Original Assignee: Superconducting Core Technologies, Inc.
• Inventors: Barnes, Frank
• Primary Examiner(s): Lee, Benny T.
• Application Number:
  US08/182,296
• Time in Patent Office: 1,418 Days
• Field of Search: 333/161, 343/700 MS
• US Class Current: 343/700.0MS
• CPC Class Codes: H01G 7/06 having a dielectric selected for the variation of its permittivity with applied voltage, i.e. ferroelectric capacitors electrets H01G7/02
• CPC Class Codes: H01P 1/181 using ferroelectric devices
• CPC Class Codes: H01P 7/082 Microstripline resonators H01P7/088 takes precedence
• CPC Class Codes: H01P 7/088 Tunable resonators
• CPC Class Codes: H01Q 1/364 using a particular conducting material, e.g. superconductor
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element

Abstract

The disclosure relates to a phased array antenna for microwave and millimeter wave applications, using either microstrip line, coplanar waveguide, or other construction techniques incorporating a solid dielectric transmission line. A continuously variable phase delay structure which is used to control the beam pattern of the phased array antenna can be applied to the construction of resonant frequency tunable coplanar waveguide antennas and impedance tunable quarter-wave transformers. A thin film of barium strontium titanate (Ba_x Sr_1-x TiO₃) or other nonlinear material such as PbZr_x Ti_1-x O₃ (PZT), LiNbO₃, etc. is deposited upon the coplanar waveguide, and/or the patch antenna element. The dielectric constant of the thin film can be made to vary significantly by applying a DC voltage to the thin film. The propagation constant of a transmission line is directly proportional to the square root of the effective dielectric constant (assuming a lossless dielectric). In an array of multiple antenna elements provided with the feed structure using the disclosed transmission lines, the direction of the resultant main beam of the array can be made to vary over a complete half-sphere with only two adjustable DC voltages applied to the dielectric thin films.

Claims

1. A phased array antenna system for microwave energy having a steerable main beam for providing half-sphere coverage, the phased array antenna system comprising:

an upper dielectric substrate;

a plurality of microstrip patch antenna elements disposed in a two dimensional phased array in rows and columns on the upper surface of the upper dielectric substrate;

a lower dielectric substrate underlying the upper dielectric substrate;

a common ground plane disposed between the upper and lower dielectric substrates and in contact therewith;

a continuously variable phased delay transmission line including a coplanar waveguide feed line disposed on the lower surface of the lower dielectric substrate;

a nonlinear dielectric thin film overlay disposed on the coplanar waveguide feed line; and

at least one of a series-feed and a corporate-feed structure connected to the two dimensional phased array to enable two independent variable DC voltages to control the phase delay between the rows and columns and thereby the phase delay between each element of the two-dimensional phased array coupled to the feed structure, the common ground plane having a plurality of apertures each in alignment with a different one of the plurality of patch antenna elements, each different aperture serving to couple microwave energy from the coplanar waveguide feed line, and through the aperture into each different microstrip patch antenna of the plurality of microstrip patch antennas on the upper dielectric substrate.

2. A single-substrate phased array antenna system having a steerable antenna main beam which provides half-sphere coverage comprising:

a substrate;

a plurality of microstrip patch antenna elements disposed in rows and columns on the substrate to define a two dimensional phased array, the plurality of microstrip patch antennas being arranged into an array;

a continuously variable phased delay transmission line feed structure including a coplanar waveguide having an overlay of a Ba_x Sr_1-x TiO₃ thin film; and

a series-feed means connected to the array for enabling two independent variable DC voltages to control the phase delay between rows and columns of the two dimensional phased array and thereby the phase delay between each microstrip patch antenna element of the two dimensional phased array.

3. A wideband phase-scanned coplanar-waveguide antenna array, the antenna array having an impedance and a resonant frequency, at least one of the impedance and the resonant frequency of the antenna array being variable, the antenna array comprising:

a substrate;

a plurality of microstrip patch antenna elements disposed in rows and columns on the substrate thereby defining a two dimensional phase array;

a continuously variable phase delay transmission line including a coplanar waveguide having an overlay of a nonlinear dielectric thin film of Ba_x Sr_1-x TiO₃ material disposed thereon;

a corporate feed means connected to the rows and columns for enabling two independent variable DC voltages to be applied to the nonlinear dielectric thin film to control the phase delay between the rows and columns of the two dimensional phased array and thereby the phase delay between each microstrip patch antenna element of the two dimensional phased array; and

a quarter-wave transformer connected between the coplanar waveguide antenna elements and the corporate feed means to provide impedance matching, the impedance matching by the quarter wave transformer increasing the bandwidth of the antenna array.

4. A coplanar waveguide device comprising;

a dielectric substrate,

a coplanar waveguide disposed on a surface of the dielectric substrate, the coplanar waveguide having a pair of upper ground planes spaced apart from one another to define an elongated interval extending therebetween, a center conductor disposed in the elongated interval in the plane of and spaced apart from each of the upper ground planes,

a lower ground plane disposed on a surface of the dielectric substrate opposite to the surface thereof upon which the coplanar waveguide is disposed; and

a nonlinear dielectric thin film disposed on the coplanar waveguide, the dielectric constant of the nonlinear dielectric thin film being a function of a variable DC voltage applied to the nonlinear dielectric thin film, a change in the dielectric constant of the nonlinear dielectric thin film changing the effective dielectric constant of the coplanar waveguide and thereby the phase delay thereof.