The Charles Stark Draper Laboratory, Inc.

University of South Florida

John E Grandfield

Thomas McCrea Weller

Gokhan Mumcu

Michael P Abban

Phillip Hulse

Amy Elizabeth Duwel

Brad D Gaynor

Jacob P Treadway

David Manuel Zaiden

Jonathan Michael O'Brien

Matthew Shea

Disclosed is a phase shifter capable of achieving 360&#xb0; phase shifts. The phase shifter includes an active balanced-to-unbalanced (balun) circuit for splitting an input signal into two signals offset in phase. The phase shifter further includes an active all-pass network electrically coupled to an output of the active balun circuit. The active all-pass network can include an active tunable inductor. A variable-gain amplifier (VGA) is electrically coupled to an output of the active all-pass network.

Switchable active balanced-to-unbalanced phase shifter

A reduced radar cross section (RCS) antenna does not require housing the antennas in a radar-mitigating radome. Elements of the antenna are made from, or include, frequency selective surfaces that reduce reflection of radar or other signals. In some embodiments, the frequency selective surfaces are electrically tunable, thereby enabling a user or system to dynamically adjust the frequency or frequencies that are mitigated.

Frequency selective surface antenna element

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.

Electronically steerable single helix/spiral antenna

A low-profile loop antenna includes a driven element disposed very close, in some cases within about 0.005 wavelengths (&#x3bb;) or closer, to a ground plane, while maintaining sizable gain and usable feed point impedance. Width of the driven element varies along its circumference, such that two diametrically opposed portions of the driven element are wider, and therefore have lower impedance, than other diametrically opposed portions of the driven element. The antenna may be configured to achieve a desired feed point impedance. The antenna may be tuned over a wide bandwidth. Metallic objects placed near the center of the antenna loop do not significantly degrade performance of the antenna. A parasitic element may be added to create a circularly-polarized antenna, without significantly increasing the antenna's profile.

Low-profile loop antenna

An antenna has a spiral driven element that meanders in a z direction, perpendicular to the x-y plane of the spiral, and a ground plane that also meanders in the z direction, such that spacing between the ground plane and the driven element is an odd multiple of one-quarter wavelength, along at least a portion of the length of the driven element. The spacing promotes constructive interference from signals reflected by the ground plane, increasing the front-to-back ratio of the antenna and, thereby, providing gain. The ground plane of a wideband version of the spiral antenna meanders, such that the spacing varies between about an odd multiple of one-quarter wavelength of an upper frequency to about an odd multiple of one-quarter wavelength of a lower frequency of a frequency range, thereby providing gain over a range of frequencies.

Ground plane meandering in Z direction for spiral antenna

In one embodiment, a periodic spiral antenna includes first and second arms that form interleaved spirals parallel to an x-y plane, wherein the arms have a height dimension that extends along a z direction that is perpendicular to the x-y plane, and wherein the interleaved spirals form multiple turns of the antenna, the turns being equally spaced from each other throughout the antenna.

Periodic spiral antennas

An electrically small dual-band planar tunable UHF/L-Band antenna. In one example, the dual-band antenna includes a combination of a semi-spiral antenna for the UHF frequencies and a microstrip patch antenna for the L-band frequencies.

Growing community of inventors

St. Petersburg, FL, United States of America

John E Grandfield