ELECTRONICALLY STEERABLE SINGLE HELIX/SPIRAL ANTENNA

• US 20150171517A1
• Filed: 12/12/2014
• Published: 06/18/2015
• Est. Priority Date: 12/14/2013
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Grandfield, John E., Abban, Michael P., Hulse, Philip, Shea, Matthew
• Granted Patent: US 9,899,746 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• CPC Class Codes: H01Q 1/362 for broadside radiating helical antennas
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 3/2629 Combination of a main antenna unit with an auxiliary antenna unit
• CPC Class Codes: H01Q 3/28 varying the amplitude
• CPC Class Codes: H01Q 3/34 by electrical means active lenses or reflecting arrays H01Q3/46
• CPC Class Codes: H01Q 9/40 Element having extended radiating surface

Abstract

An electronically steerable helical or spiral antenna includes a monopole antenna element disposed within at least one helical or spiral antenna element. The antenna can be electronically steered, i.e., its radiation pattern can be altered, such that the antenna radiates in a desired direction, without mechanically changing a direction in which the antenna is aimed and without mechanically changing orientation of any of the antenna'"'"'s elements, by adjusting amplitude and phase of a signal fed to the monopole antenna element, relative to a signal fed to the at least one helical or spiral antenna element.

Claims

1. An electronically steerable radio frequency antenna, comprising:

at least one helical antenna element wound about a single longitudinal axis and defining a volume; and

;

a straight antenna element disposed within the volume and oriented along the single longitudinal axis, the straight antenna element being configured to be fed at a proximal end, the distal end of the straight antenna element terminating without electrical connection to any other antenna element.

2. An electronically steerable radio frequency antenna according to claim 1, further comprising a feed circuit electrically coupled to the at least one helical antenna element and to the straight antenna element.

3. An electronically steerable radio frequency antenna according to claim 2, wherein the feed circuit is configured to receive an input signal and to:

provide a first version of the input signal to the at least one helical antenna element;

provide a second version of the input signal to the straight antenna element; and

control relative amplitude and relative phase of the first and second versions of the input signal.

4. An electronically steerable radio frequency antenna according to claim 3, wherein the feed circuit comprises a variable delay circuit configured to control the relative phase of the first and second versions of the input signal.

5. An electronically steerable radio frequency antenna according to claim 1, further comprising a ground plane disposed adjacent one end of the at least one helical antenna element and oriented perpendicular to the single longitudinal axis.

6. An electronically steerable radio frequency antenna according to claim 1, wherein the at least one helical antenna element comprises four helical antenna elements arranged as a quadrifilar helix.

7. An electronically steerable radio frequency antenna according to claim 6, further comprising a feed circuit electrically coupled to the straight antenna element and to each antenna element of the four helical antenna elements and configured to receive an input signal and to:

provide a first version of the input signal to the at least one helical antenna element;

provide a second version of the input signal to the straight antenna element; and

control relative amplitude and relative phase of the first and second versions of the input signal.

8. A method for electronically steering a radio frequency antenna, the method comprising:

receiving an input signal;

providing a first version of the input signal to at least one helical antenna element;

providing a second version of the input signal to a straight antenna element disposed along an axis of the at least one helical antenna element and within a volume defined by the at least one helical antenna element; and

controlling relative amplitude and relative phase of the first and second versions of the input signal.

9. A method according to claim 8, wherein controlling the relative amplitude and the relative phase of the first and second versions of the input signal comprises:

adjusting the relative amplitude of the second version of the input signal according to a phi direction control signal; and

adjusting the relative phase of the second version of the input signal according to a theta direction control signal.

10. A method according to claim 9, wherein adjusting the relative phase of the second version of the input signal comprises delaying the second version of the input signal by an amount that depends on the theta direction control signal.