SYSTEM AND METHOD FOR MODULATING A SIGNAL AT AN ANTENNA

• US 20090220030A1
• Filed: 11/25/2008
• Published: 09/03/2009
• Est. Priority Date: 02/28/2008
• Status: Active Grant

• Current Assignee: Altamira Technologies Corporation
• Original Assignee: Invertix
• Inventors: Law, Daniel A., Uhl, Brecken H., Hurtado, Arthur D.
• Granted Patent: US 8,340,197 B2
• Time in Patent Office: Days
• US Class Current: 375/329
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits

Abstract

A Direct Spatial Antenna Modulation (DSAM) antenna structure makes use of the instantaneous electromagnetic field state of a radiating antenna structure to achieve direct modulation of a transmitted signal within the antenna. In contrast to existing amplitude and phase-only based digital modulation techniques, this innovative technique utilizes an inherent spatial modulation component, mapping data spatially to different locations in the antenna structure, where each location has different transmitting and receiving properties. This spatial component of the modulation can enable, for example, a unique increase in data transmission speed in a fixed spectral bandwidth with no increase in bit error rate over current phase and amplitude only modulation techniques. Additionally, the DSAM antenna structure affords important benefits in reduced hardware complexity, reduced supply current consumption, and relaxed amplifier linearity requirements. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this Abstract.

Claims

1. A direct spatial antenna modulation (DSAM) antenna comprising:

a radiating structure comprising spatial points of origination;

a common feed point for receiving a carrier signal that is unmodulated; and

a switching system responsive to a baseband data signal, wherein the switching system directs the unmodulated carrier signal to at least one spatial point of origination thereby modulating the carrier signal.

2. The DSAM of claim 1, wherein the radiating structure is excited by the unmodulated carrier signal at the at least one spatial point of origination.

3. The DSAM of claim 1, wherein a unique data symbol is associated with a spatial point of origination, and wherein in response to the presence of the unique data symbol in the baseband data signal, the switching system directs the unmodulated carrier signal to the spatial point of origination associated with the particular unique data symbol.

4. The DSAM of claim 1, wherein the baseband data signal comprises unique data symbols and wherein the switching system in response to the presence of the unique data symbols in the baseband signal causes the radiating structure to produce a modulated signal selected from the group consisting of a quadrature phase shift keying (QPSK) modulated signal, a binary phase shift keying (BPSK) modulated signal, and a dual circular polarized QPSK signal.

5. The DSAM of claim 1, wherein the modulated carrier signal is linearly polarized.

6. The DSAM of claim 1, wherein the modulated carrier signal is circularly polarized.

7. The DSAM of claim 6, wherein the circular polarization is selected from the group consisting of left hand circular polarization and right hand circular polarization.

8. The DSAM of claim 1, wherein the antenna structure comprises a square microstrip patch antenna further comprising:

a ground layer;

a top layer, wherein the top layer is situated above the ground layer and separated therefrom by a first dielectric layer and wherein the top layer comprises;

feed ports located opposite of a mid-point of each side of the square microstrip patch antenna, wherein each feed port establishes a signal path to a spatial point of origination;

top layer switching system elements at each corner; and

top layer transmission lines, wherein the top layer transmission lines are situated parallel to the edges of the top layer and connect the top layer switching elements in response to the digital data signal; and

a bottom layer, wherein the bottom layer is situated below the ground layer and is separated therefrom by a second dielectric layer, and wherein the bottom layer comprises;

bottom layer switching system elements each associated with a single feed port; and

bottom layer transmission lines, wherein the bottom layer transmission lines connect a first side of a bottom layer switching element to the common feed point and a second side of the bottom layer switching element to feed port associated with the bottom layer switching element in response to the digital data signal,

wherein, the top layer transmission lines, top layer switching elements, bottom layer transmission lines and bottom layer switching elements are configured so as to cause the square microstrip patch antenna to provide an odd multiple of ¼

guided wavelength electrical delay over the desired operating band of the device with respect to the common feed location, spatial points of origination, and switching system elements.

9. The DSAM of claim 1, wherein the switching system comprises a switching RF PIN diode.

10. The DSAM of claim 1, wherein a unique data symbol is associated with at least two spatial points of origination, and wherein in response to the presence of the unique data symbol in the baseband data signal, the switching system directs the unmodulated carrier signal to the at least two spatial points of origination associated with the unique data symbol.

11. The DSAM of claim 10, wherein the radiating structure is excited by the unmodulated carrier signal at the at least two spatial points of origination.