Array antenna with shaped beam pattern for toll road collection system applications
First Claim
1. An array antenna for toll collection over a first rectangular zone, the antenna comprising:
- a plurality of elements; and
a feed network operatively coupled to the plurality of elements;
the elements and the feed network being configured to form a first asymmetric transmitting antenna pattern and a first asymmetric receiving antenna pattern, the first transmitting antenna pattern being asymmetric in azimuth about a direction of maximum gain and being substantially the same as the first receiving antenna pattern, and the first transmitting antenna pattern having a gain exceeding a threshold over the first rectangular zone, and a gain less than the threshold in a region outside of the first rectangular zone.
1 Assignment
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Accused Products
Abstract
A system for properly illuminating a toll collection zone without illuminating any areas outside the toll collection zone in which vehicles may be found, while minimizing lost tolls due to shadowing of shorter vehicles by taller vehicles. In one embodiment, a linear array antenna is configured to illuminate a rectangular collection zone from a point offset from the center of the roadway. The linear array antenna is configured to produce an asymmetric antenna pattern providing RF illumination over the rectangular collection zone sufficient for reliable reading of vehicle RF tags in the collection zone, and which also minimizes spillover of RF power outside the collection zone.
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Citations
20 Claims
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1. An array antenna for toll collection over a first rectangular zone, the antenna comprising:
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a plurality of elements; and a feed network operatively coupled to the plurality of elements; the elements and the feed network being configured to form a first asymmetric transmitting antenna pattern and a first asymmetric receiving antenna pattern, the first transmitting antenna pattern being asymmetric in azimuth about a direction of maximum gain and being substantially the same as the first receiving antenna pattern, and the first transmitting antenna pattern having a gain exceeding a threshold over the first rectangular zone, and a gain less than the threshold in a region outside of the first rectangular zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification