Time variant antenna for transmitting wideband signals

• US 10,135,650 B2
• Filed: 11/20/2014
• Issued: 11/20/2018
• Est. Priority Date: 11/20/2013
• Status: Active Grant

• Current Assignee: Virginia Tech Intellectual Properties, Inc. (Virginia Polytechnic Institute and State University)
• Original Assignee: Virginia Tech Intellectual Properties, Inc. (Virginia Polytechnic Institute and State University)
• Inventors: Manteghi, Majid, Salehi, Mohsen
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US15/038,394
• Publication Number:
  US 20160294056A1
• Time in Patent Office: 1,461 Days
• Field of Search: 4551641, 455119, 4551731, 4551821, 4551822, 4551922, 455257
• CPC Class Codes: H01Q 3/34 by electrical means active lenses or reflecting arrays H01Q3/46
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
• CPC Class Codes: H01Q 5/00 Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements combinations of separate active antenna units operating in different wavebands and connected to a common feeder system H01Q21/30
• CPC Class Codes: H01Q 5/25 Ultra-wideband [UWB] systems, e.g. multiple resonance systems; Pulse systems
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/04 Circuits
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits

Abstract

A circuit for tuning a resonance frequency of an electrically small antenna. The circuit includes a first source configured for providing a modulation signal, a second source configured for providing a periodic electrical signal, an antenna, and a tuning circuit configured for modulating a resonance frequency of the antenna in response to the modulation signal. The tuning circuit includes first and second capacitors that are alternately coupled to the antenna to change the resonance frequency of the antenna. The capacitor currently coupled to the antenna is decoupled from the antenna and the other capacitor is coupled to the antenna when the voltage across the capacitor currently coupled to the antenna is momentarily zero. In an exemplary embodiment, the tuning circuit comprises first and second inductors rather than capacitors. The inductors are switched into and out of the circuit when the current through the currently coupled inductor is momentarily zero.

Claims

1. A circuit for tuning a resonance frequency of an electrically small antenna, the circuit comprising:

a first source configured for providing a modulation signal;

a second source configured for providing a periodic electrical signal;

an antenna; and

a tuning circuit comprising;

a first capacitive device;

a second capacitive device; and

a switch configured for alternately coupling the first capacitive device and the second capacitive device to the antenna for modulating a resonance frequency of the antenna between a first resonant frequency and a second resonant frequency and only between the first resonant frequency and the second resonant frequency in response to the modulation signal,

wherein the first source is configured for providing the modulation signal to the tuning circuit so that the switch alternately couples one of the first capacitive device and the second capacitive device to the antenna while decoupling the other one of the first capacitive device and the second capacitive device from the antenna when a voltage across the other one of the first capacitive device and the second capacitive device is zero.

2. The circuit of claim 1, wherein the modulation signal is a digital signal, and wherein the switch is a solid state device configured for alternately coupling the one of the first capacitive device and the second capacitive device to the antenna while decoupling the other one of the first capacitive device and the second capacitive device from the antenna.

3. The circuit of claim 1, wherein the tuning circuit comprises a first capacitive device and a switch configured for controllably coupling the first capacitive device to and decoupling the first capacitive device from the antenna in response to the modulation signal when a voltage applied to the antenna by the periodic electrical signal is zero.

4. The circuit of claim 1, wherein the tuning circuit comprises a first inductive device and a switch configured for controllably coupling the first inductive device to and decoupling the first inductive device from the antenna for modulating the resonance frequency of the antenna when powered by the periodic electrical signal.

5. The circuit of claim 1, wherein the tuning circuit comprises a first inductive device and a switch configured for controllably coupling the first inductive device to and decoupling the first inductive device from the antenna in response to the modulation signal when a current provided to the antenna by the periodic electrical signal is zero for modulating the resonance frequency of the antenna.

6. The circuit of claim 1, wherein the antenna is an electrically small antenna.

7. A method for tuning a resonance frequency of an electrically small antenna, the method comprising steps of:

generating a modulation signal;

generating a periodic electrical signal;

powering an antenna with the periodic electrical signal; and

modulating a resonance frequency of the antenna between a first frequency and a second frequency and only between the first frequency and the second frequency in response to the modulation signal by alternately coupling a first capacitive device and a second capacitive device to the antenna; and

decoupling the other one of the first capacitive device and the second capacitive device from the antenna when a voltage across the other one of the first capacitive device and the second capacitive device is zero.

8. The method of claim 7, wherein the step of modulating comprises controllably coupling a first capacitive device to and controllably decoupling the first capacitive device from the antenna in response to the modulation signal when a voltage applied to the antenna by the periodic electrical signal is zero.

9. The method of claim 7, wherein the step of modulating comprises controllable coupling a first inductive device to and controllably decoupling the first inductive device from the antenna to modulate the resonance frequency of the antenna between the first frequency and the second frequency in response to the modulation signal.