Helical antenna with small reflector
A helical antenna and reflective surface technology, applied in the field of transmitters, can solve the problems of unsuitable transmitting antennas, no gain, and low radiation efficiency of small loop antennas, so as to meet the requirements of long-distance communication, increase the gain, and increase the transmission coverage. Effect
Inactive Publication Date: 2016-08-17
BAOLONG HUF SHANGHAI ELECTRONICS CO LTD
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Problems solved by technology
The structure of this antenna is simple, and its disadvantage is that the radiation resistance of the small loop antenna whose circumference is much smaller than the wavelength is smaller than its loss resistance, resulting in low radiation efficiency of the small loop antenna and low gain of the small loop antenna , not suitable for transmitting antennas for long-distance communication transmitters
[0006] (4) Chip antenna: This antenna uses sheet metal as the antenna radiator, which is an electrically small antenna. Its small structure just meets the requirements of the small structure of the TPMS system transmitter. However, it has no good gain like the above-mentioned antenna. , it is possible to apply to passenger cars, but it cannot meet the requirements for trucks or large-volume vehicles
[0007] Given that current antenna solutions do not meet the requirements for a transmitter antenna for a truck or bulky vehicle TPMS system, an improved antenna is expected to meet this requirement
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[0019] In the embodiment of the present invention, in order to improve the antenna gain and meet the long-distance communication requirements of the TPMS system for trucks or large-volume vehicles, on the basis of the existing helical antenna technology, the small reflector technology is applied to the transmitting antenna scheme of the TPMS system transmitter.
[0020] It is well known that large reflectors (effective diameter approximately equal to one wavelength) can change the input impedance, antenna pattern, and increase antenna gain. However, in the tire pressure monitoring system (TPMS) system, this large reflective surface technology is difficult to be applied. The main reason is that the frequency currently used by the TPMS system is 434MHz or 315MHz, and their wavelengths are λ(434MHz)=691mm and λ(315MHz)=952.4mm respectively. The TPMS system requires the transmitter to be small in size and light in weight, and there is no large space to realize it.
[0021] The ge...
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The invention discloses a helical antenna with a small reflection surface, which is used to increase the gain of the helical antenna, increase the transmission coverage of a transmitter, and meet the long-distance communication requirements of a TPMS system. For this purpose, the helical antenna includes a body and a reflective surface. The main body is a helical structure made of metal wire or metal tube, and the main body is a helical antenna in a normal mode. The reflection surface is set under the body and is connected to the negative electrode or the ground wire of the body feed point. The reflective surface satisfies: A-x≤(D0-D) / 2≤A, where D is the spiral diameter of the body, D0 is the diameter of the reflective surface, A and x are a constant, and 0<x<A≤ 0.01λ, λ is the wavelength of the transmitter's emission signal in free space.
Description
technical field [0001] The present invention relates to transmitters suitable for use in tire pressure monitoring systems (TPMS systems) for trucks or mass vehicles, and more particularly to helical antennas with small reflective surfaces for such transmitters. Background technique [0002] The tire pressure monitoring system (TPMS) is mainly used to detect the pressure and temperature of automobile tires, to give early warning of possible dangers caused by tire pressure and temperature, to ensure driving safety, and to reduce the accelerated tire wear and increased energy consumption caused by insufficient air pressure. system. The TPMS system communicates wirelessly through RF. Due to the strict limitation of the electromagnetic environment on the field strength, the theoretical transmission power value in the transmission module is continuously reduced. And with the increase of the volume of the vehicle, the requirements of the system for RF communication are getting hi...
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IPC IPC(8): H01Q11/08H01Q15/14
Inventor 徐长武李威韩文斌
Owner BAOLONG HUF SHANGHAI ELECTRONICS CO LTD