System and method for estimating an angle of arrival
View Patent ↗A system and method for estimating an angle of arrival. In some embodiments, the system includes an array antenna and a processing circuit. The array antenna may be curved, and may include a first radiator having a first resonant frequency and a second radiator having a second resonant frequency different from the first resonant frequency. The processing circuit may be configured to receive a signal from the array antenna and to calculate, from the signal, an estimated angle of arrival of electromagnetic radiation corresponding to the signal.
1 . A system, comprising:
an array antenna;
a radio frequency (RF) front end; and
a processing circuit,
the array antenna being curved,
the array antenna comprising a plurality of radiators, including a first radiator having a first resonant frequency and a second radiator having a second resonant frequency different from the first resonant frequency, the plurality of radiators comprising at least 10 radiators,
the processing circuit being configured to receive a signal from the array antenna and to calculate, from the signal, an estimated angle of arrival of electromagnetic radiation corresponding to the signal,
wherein:
the array antenna comprises a substrate integrated waveguide,
the substrate integrated waveguide has the shape of a hollow cylinder,
the array antenna has a first feed and a second feed,
the two feeds are at diametrically opposed positions on the hollow cylinder, and
the calculating of the angle of arrival comprises calculating a normalized cross correlation vector, the normalized cross correlation vector comprising, for each of a plurality of frequency points, a normalized cross correlation of a signal at the first feed and a signal at the second feed.
2 . The system of claim 1 , wherein:
the first radiator is a complementary I-shaped resonator, and
the second radiator is a complementary I-shaped resonator.
3 . The system of claim 1 , wherein the radiators of the plurality of radiators are uniformly spaced around the hollow cylinder.
4 . The system of claim 3 , wherein each of the plurality of radiators has a respective resonant frequency, the respective resonant frequencies being nonuniformly distributed.
5 . The system of claim 1 , wherein the calculating further comprises:
calculating, for a first tentative angle of arrival, a first discrepancy, the first discrepancy being a measure of the difference between a reference normalized cross correlation vector and the calculated normalized cross correlation vector;
calculating, for a second tentative angle of arrival, a second discrepancy, the second discrepancy being a measure of the difference between a reference normalized cross correlation vector and the calculated normalized cross correlation vector;
determining that the first discrepancy is greater than the second discrepancy; and
setting the estimated angle of arrival equal to the second tentative angle of arrival.
6 . The system of claim 1 , wherein the calculating further comprises calculating the estimated angle of arrival using ridge regression based on a reference response of the array antenna for a plurality of angles of arrival.
7 . A method, comprising:
receiving an electromagnetic signal with an array antenna, to generate an antenna signal; and
calculating, by a processing circuit, from the antenna signal, an estimated angle of arrival of the electromagnetic signal,
wherein:
the array antenna is curved,
the array antenna has a first feed and a second feed,
the array antenna comprises a first radiator having a first resonant frequency and a second radiator having a second resonant frequency different from the first resonant frequency, and
the calculating of the angle of arrival comprises calculating a normalized cross correlation vector, the normalized cross correlation vector comprising, for each of a plurality of frequency points, a normalized cross correlation of a signal at the first feed and a signal at the second feed.
8 . The method of claim 7 , wherein:
the first radiator is a complementary I-shaped resonator, and
the second radiator is a complementary I-shaped resonator.
9 . The method of claim 7 , wherein the array antenna comprises a substrate integrated waveguide.
10 . The method of claim 9 , wherein the array antenna comprises a plurality of radiators, including the first radiator and the second radiator, the plurality of radiators comprising at least 10 radiators.
11 . The method of claim 10 , wherein the substrate integrated waveguide has the shape of a hollow cylinder.
12 . The method of claim 7 , wherein the calculating further comprises:
calculating, for a first tentative angle of arrival, a first discrepancy, the first discrepancy being a measure of the difference between a reference normalized cross correlation vector and the calculated normalized cross correlation vector;
calculating, for a second tentative angle of arrival, a second discrepancy, the second discrepancy being a measure of the difference between a reference normalized cross correlation vector and the calculated normalized cross correlation vector;
determining that the first discrepancy is greater than the second discrepancy; and
setting the estimated angle of arrival equal to the second tentative angle of arrival.
13 . The method of claim 7 , wherein the calculating further comprises calculating the estimated angle of arrival using ridge regression based on a reference response of the array antenna for a plurality of angles of arrival.