# US 12,183,981 B2 · Grating lobe cancellation

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- Number: US 12,183,981 B2
- Document ID: US12183981B2
- Status: Granted
- Kind: B2
- Application number: 18/366,863
- Filed: 2023-08-08
- Published: 2024-02-22
- Granted: 2024-12-31
- Earliest claimed: 2022-07-20
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: Naval Information Warfare Center Pacific
- Inventors: Jia-Chi Samuel Chieh
- Web page: https://patentgrep.com/patent/US12183981B2

## CPC

- H01Q 3/26: varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture ({H01Q3/12,} H01Q3/22, H01Q3/24 take precedence)
- H01Q 21/293: {one unit or more being an array of identical aerial elements (adaptive arrays H01Q3/2605)}
- H01P 5/16: Conjugate devices, i.e. devices having at least one port decoupled from one other port
- H01Q 9/0478: {with means for suppressing spurious modes, e.g. cross polarisation}
- H01Q 21/08: the units being spaced along or adjacent to a rectilinear path {(waveguide fed H01Q21/0037)}
- H01Q 21/10: Collinear arrangements of substantially straight elongated conductive units
- H01Q 25/04: Multimode antennas {(corrugated horns H01Q13/0208)}
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)

## Abstract

A method for radiating a co-located antenna including radiating the co-located antenna using a dual mode, where the co-located antenna has an inter-element spacing of about 1λ and the dual mode includes a TM11 mode and a TM21 mode. The TM11 mode is radiated to generate a TM11 far field pattern, where the TM11 mode has a broadside pattern characterized with a beam peak at broadside and the TM11 mode produces grating lobes in addition to the beam peak at broadside. The TM21 mode is radiated to generate a TM21 far field pattern orthogonal to the TM11 far field pattern, thereby causing the TM21 mode to produce a null at broadside to suppress the grating lobes produced by the TM11 mode.

## Claims

### Claim 1

An antenna system, comprising:
a multi-mode antenna having a plurality of radiating elements, wherein the radiating elements have an inter-element spacing of 12 and can radiate in a dominant mode and an auxiliary mode where 2 is a wavelength of an operating frequency band of the multi-mode antenna;
a beamformer, wherein the beamformer is integrated with a multi-chip module;
an indium phosphate (InP) low noise amplifier;
a gallium nitride (GaN) high power amplifier; and
wherein the multi-mode antenna suppresses grating lobes by:
i) applying an identical amplitude and phase to the dominant mode and auxiliary mode;
ii) adjusting a phase shift until the null appears;
iii) adjusting the auxiliary mode amplitude by using a 0.5 dB attenuation; and
iv) repeating ii) and iii) until equal to or less than 30 dB of cancellation been achieved.

### Claim 2 (depends on 1)

The system of claim 1, wherein the multi-mode antenna is a co-located antenna selected from the group consisting of a phased array antenna, a 2D planar array antenna, or a triangular lattice antenna and the dominant mode is a TM11 mode and the auxiliary mode is a TM21 mode.

### Claim 3 (depends on 1)

The system of claim 1, wherein the multi-mode antenna is a tapered slot antenna and the dominant mode is a differential mode and the auxiliary mode is a common mode.

### Claim 4 (depends on 1)

The system of claim 1, wherein the multi-mode antenna is a phased array antenna is a 16-element linear phased array antenna.

### Claim 5 (depends on 1)

The system of claim 1, wherein the dominant mode produces a beam and grating lobes and the auxiliary mode produces a null that cancels the grating lobes.

### Claim 6 (depends on 2)

The system of claim 2, wherein the co-located antenna includes both antennas on a single metal substrate.

### Claim 7 (depends on 1)

The system of claim 1, wherein the beamformer is a silicon germanium beamformer integrated with a multi-chip module.

### Claim 8

An antenna system, comprising:
a multi-mode antenna having a plurality of radiating elements, wherein the radiating elements have an inter-element spacing of 12 and can radiate in a dominant mode and an auxiliary mode where 2 is a wavelength of an operating frequency band of the multi-mode antenna;
a beamformer, wherein the beamformer is integrated with a multi-chip module;
a gallium nitride (GaN) high power amplifier; and
wherein the multi-mode antenna suppresses grating lobes by:
i) applying an identical amplitude and phase to the dominant mode and auxiliary mode;
ii) adjusting a phase shift until the null appears;
iii) adjusting the auxiliary mode amplitude by using a 0.5 dB attenuation; and
iv) repeating ii) and iii) until equal to or less than 30 dB of cancellation been achieved.