Patent Application
20120068909
The invention relates to an antenna configured to improve radiation efficiency.
Current radar systems operating at the microwave range include an antenna. The antenna includes an array of resonating elements mounted onto a substrate. The antenna array includes a plurality of resonating lines. Each resonating line includes a plurality of axially aligned resonators. Power is supplied to each resonating line through a feed line.
In certain embodiments, the feed line is proximately coupled to each of the resonating lines. The feed lines are mounted on the substrate and are generally disposed beneath the resonating lines. Electricity is supplied along the feed lines, actuating the resonators so as to receive echoes from a transmitting antenna. However, a concentration of electrical field forms along the mid portion of the antenna array, as shown in
Accordingly, it remains desirable to have an antenna having an array proximately coupled to the feed line which reduces the concentration of electrical field along the mid portion of the antenna array.
According to one aspect of the invention, an antenna for use in an automobile is provided. The antenna includes an array proximately coupled to a feed line. The antenna array includes a plurality of resonating lines. Each resonating line includes a plurality of axially aligned resonators. Power is supplied to each resonating ling through the feed line. The resonators have a resonating surface. The resonating surfaces of the resonators at the ends of the resonating lines are larger than resonating surfaces of the resonators in the middle of the resonating lines.
Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
With reference first to
The antenna 10 includes a substrate 12 formed of a dielectric material. The substrate 12 includes a first surface 14 opposite a second surface 16. The substrate 12 may be formed of multiple layers 18, 20 of dielectric material. The substrate 12 has a predetermined thickness configured to optimize the radiation efficiency of the antenna 10.
An antenna array 22 is disposed on the first surface 14 of the substrate 12. The antenna array 22 has a plurality of resonating lines 24, and each resonating line 24 has a plurality of resonators 26 axially aligned to each other. Each of the plurality of resonators 26 has a resonating surface 28. The resonating surfaces 28 of the resonators 26 at the ends of the resonating line 24 are larger than the resonating surfaces 28 of the resonators 26 in the middle of the resonating line 24. Thus the resonators 26 are tapered from the ends of the resonating line 24 to the middle of the resonating line 24.
A plurality of feed lines 30 provides power to the antenna 10. More specifically, each feed line 30 is proximately coupled to a resonating line 24 in the antenna array 22. The feed line 30 is formed of an electrical conductive material such as copper, gold or the like. The feed line 30 has a predetermined width that is configured to generate a desired impedance at each of the resonators 26. The feed lines 30 are spaced apart the resonating lines 24. Each feed line 30 is axially aligned with and generally directly below a corresponding resonating line 24.
With reference again to
The feed line 30 is proximately coupled to each of the resonating lines 24. As shown in
Electricity is supplied to each feed line 30, actuating the individual resonators 26. The electricity creates a magnetic inductance which excites the resonators 26. As each resonator 26 is excited, an electrical field is generated. The strength of the electrical field is dependent upon the amount of electricity supplied along the feed line 30 and the size of the resonating surfaces 28 of the resonators 26.
The electrical field accumulates along the middle of the antenna array 22 due to the excitement of adjacent resonators 26. Since there is a large concentration of resonators 26 in the middle of the antenna array 22, a larger concentration of electrical field is found in the middle of the antenna array 22. As known in proximately coupled arrays 22 of the prior art, the concentration of electrical field reduces the radiation efficiency of the resonators 26.
The present invention overcomes this problem by reducing the magnitude of the electrical field generated by each of the resonators 26 in the middle of the antenna array 22. This is done by having the resonating surface 28 of the resonators 26 in the middle of the antenna array 22 smaller than the resonating surface 28 of the resonators 26 at the ends of the resonating lines 24.
The electrical field in the middle of the antenna array 22 is still accumulated. However, since the electrical field generated by the resonators 26 in the middle of the array 24 is smaller, the concentration of the electrical field in the middle may be configured to be the same as the electrical field generated at the ends of the resonating lines 24. Thus, the electrical field is generally uniform along each of the resonating lines 24. The uniform electrical field along the antenna array 22 improves the radiation efficiency of the antenna 10 relative to prior art antennas.
With reference now to
The invention has been described in an illustrative manner. It is therefore to be understood that the terminology used is intended to be in the nature of the words of description rather than limitation. Many modifications and variations of the invention are possible in light of the above teachings. For example, the antenna 10 may include thirty-two resonating lines 24, each having thirty-two resonators 26. Thus within the scope of the appended claims the invention may be practiced other than as specifically described.
