Low loss quadrature matching network for quadrifilar helix antenna

• US 5,594,461 A
• Filed: 05/25/1995
• Issued: 01/14/1997
• Est. Priority Date: 09/24/1993
• Status: Expired due to Fees

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: Rockwell International Corporation
• Inventors: O'Neill, Gregory A. Jr.
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): PHAN, THO GIA
• Application Number:
  US08/450,737
• Time in Patent Office: 600 Days
• Field of Search: 343/895, 343/702
• US Class Current: 343/895
• CPC Class Codes: H01Q 11/08 Helical antennas
• CPC Class Codes: H01Q 21/0025 Modular arrays

Abstract

A quadrifilar antenna has first, second, third and fourth quadrature antenna elements with signals in a respective quadrature phase relationship. The antenna elements are coupled through a quadrature matching network to a transceiver circuit representing a load or a source. The matching network includes first, second and third transmission lines which are arranged in a "Z" configuration. The first transmission line matches impedances between the first and second antenna elements and communicatively couples the second antenna element with a quarter wavelength phase shift of its signals to the first antenna element. The second transmission line matches impedances between the third and fourth antenna elements and communicatively couples the fourth antenna element with a quarter wavelength phase shift of its signals to the third antenna element. The third transmission line matches the resultant impedance of the coupled third and fourth antenna elements to the resultant impedance of the coupled first and second antenna elements and couples the third and fourth antenna elements to the coupled first and second antenna elements with a half wavelength phase shift of the respectively coupled signals. A fourth transmission line matches the resultant impedance of and couples the coupled first, second, third and fourth antenna elements to the load.

Claims

1. A quadrature matching network in a quadrifilar antenna assembly of a quadrifilar helical antenna of first, second, third and fourth antenna elements of a radio, each antenna element having a proximal end and a distal end being a free end, each antenna element being coupled, at its proximal end only, to the quadrature matching network each antenna element having an impedance, and each antenna element communicating signals in a 90 degree phase relationship with respect to any adjacent one of the antenna elements, the quadrature matching network comprising:

a first transmission line element of a characteristic impedance matching the impedance of the second antenna element to the impedance of the first antenna element, the first transmission line element coupling the second antenna element to the first antenna element and transforming the phase of the communicated signal of the second antenna element to the phase of the communicated signal of the first antenna element;

a second transmission line element of a characteristic impedance matching the impedance of the fourth antenna element to the impedance of the third antenna element, the second transmission line element coupling the fourth antenna element to the third antenna element and transforming the phase of the communicated signal of the fourth antenna element to the phase of the communicated signal of the third antenna element;

a third transmission line element having a characteristic impedance matching the impedance of the coupled third and fourth antenna elements to the impedance of the coupled first and second antenna elements, the third transmission line element coupling the third and fourth antenna elements to the first and second antenna elements and transforming the phase of the communicated signal of the coupled third and fourth antenna elements to the phase of the communicated signal of the coupled first and second antenna elements; and

a fourth transmission line element having a characteristic impedance matching the impedance of the coupled first, second, third and fourth antenna elements to the impedance of the radio wherein said first, second, third and fourth transmission line elements are combined on a single circuit board spaced at the proximal ends of said first, second, third and fourth antenna elements.

2. The quadrature matching network according to claim 1, wherein the radio is in a transmit mode and the impedance of the radio constitutes a source impedance.

3. The quadrature matching network according to claim 1, wherein the radio is in a receive mode and the impedance of the radio constitutes a load impedance.