The LTCC Integrated Airborne Radar Antenna Technology

With the rapid development of the Internet of Things, Wireless sensing technology, which is the key of Internet of Things, makes a great progress. However, a problem has troubled the researchers of wireless sensing technology for a long time. How to ensure the energy supply of wireless sensor and other wireless devices which are used in the wireless sensing technology? To solve the problem, several ways of power supply have been proposed, such as solar, mechanical vibration and thermal effect. Unfortunately, each of them gets different restrictions in the nature environment. Compared with them, getting the power from the collection of microwave power in the surrounding environment by ambient microwave harvesting has more advantages.Ambient microwave harvesting technology come from the microwave power transmission(MPT). The microwave power is harvested by rectenna, which is the receiving modules in MPT. Rectenna is widely used in many areas, but in ambient microwave harvesting it is facing two challenges. Firstly, it is too hard to get enough input microwave energy for a high efficiency in the rectifying circuit, as the ambient microwave is quiet weak. Secondly, the output voltage is too low to be useful. This paper tries to solve the two problems by designing a duel-frequency microwave rectifying circuit for low input power.The main contents of this paper are as follows:By studying the basic principle of rectifying circuit, it proposed the methods to design a rectifying circuit. At the same time, with making comparison of several different structures of rectifying circuit, it concluded the advantages and disadvantages of different rectifying circuit structures. Then the formulations of voltage and current of the rectifying diode in the rectifying circuit was inferred and the influence of the rectifying diode on the rectifying efficiency was given. Finally, it proposed the requirement of rectifying diode for low input power rectifying circuit and the formulations to calculate the input impedance of diode and the efficiency of the rectifying circuit which made the preparation for the designing of rectifying circuit for low input power.When introducing the relevant principles of impedance matching, several basic structures to match different impedances was proposed and was simulated in advance design system(ADS). The impedance of the rectifying diode at 850 MHz and 1900 MHz was matched by a dual-band matching network which contained a ∏-structure. A rectifying circuit worked at 850 MHz and 1900 MHz was designed.The new designed dual-band rectifying circuit which worked at 850 MHz and 1900 MHz, was simulated in ADS. When input power was 1mW, the rectifying circuit got output 0.66 V and 0.64 V at 850 MHz and 1900 MHz, respectively. And the rectifying efficiency was 72.6% and 68.1%. After the rectifying circuit was made in real, the measured conversion efficiencies of 47% and 81.4% were obtained at 850 MHz and 1900 MHz. And output was 0.53 V and 0.7 V while input power was also 1 mW. When receiving both frequency signals The output could reach 0.85 V.