Design Of Electrically-Small Antenna In Wireless Sensor Package

In recent years, with the concept of "Internet+" proposed, wearable device, the micro sensor, intelligent hardware become the new trend. Thus, antennas in small wireless sensor module encapsulation become the urgent demand of the industry.According to one micro wireless sensor, under the condition of physical size 1/50～1/100, a loop antenna working at 434 MHz is designed and encapsulated.In this thesis, firstly, some theoretical foundation knowledge of antenna is introduced. The characteristics of small electric dipole and magnetic loop antenna are investigated after that. Then current antenna miniaturization technology such as, structural optimization, load technology, the use of artificial materials and ceramic substrate are summarized and compared. On this basis and combining the characteristics of loop antenna, the design and performance of an electrically small loop antenna standing on compact ground in wireless sensor package is presented. The loop antenna works at 434MHz ISM band with the size 18mm×l8mm×12mm. Performance is simulated in CST complied with measurement. Over 5MHz of-lOdB impedance bandwidth and more than 22% measured efficiency in the frequency are achieved.In the end, as the measured radiation pattern is not according with the expected, applying the ferrite cores for radiation patterns test is proposed and the basic theory of ferrite cores is also introduced, which shows that the core is indispensable in the measurement of electrically small loop antenna.