| Transmission line monitoring system is an important guarantee for the safe and reliable operation of modern complex power network.Modern transmission line monitoring systems will install detection devices on fixed poles and towers or sections,as well as UAV monitoring devices.These devices mainly rely on wireless networks(WIFI,WIMAX)to achieve interconnection.Therefore,high quality antenna sensor can reduce the error of receiving and receiving signals between devices and improve the reliability of monitoring system.In order to adapt to the characteristics of miniaturization and multi-band of modern equipment,the technological advantages of LTCC are conducive to the development of antennas to meet these characteristics.LTCC(Low Temperature Co-fired Ceramics)technology can encapsulate a variety of passive devices in multi-layer ceramic substrates by using advanced technology,which can realize antenna receiving and receiving multiple bands of electromagnetic waves.The characteristics of high frequency and high Q of ceramic materials are effective ways to reduce antenna volume.Firstly,based on LTCC technology,a double-band zigzag antenna with size of 6.9 X 12.7×1.11 mm3 is designed.The resonant frequencies of the antenna are 4.60 GHz and 5.80 GHz respectively.The simulation results of HFSS show that the frequency bandwidth of the antenna is 330 MHz and 350 MHz respectively when the VSWR is 2.5(the return loss is-7.5 dB).Although the radiation direction of the antenna is still omnidirectional,the antenna has poor directional characteristics due to cross-polarization.In order to meet the practical application requirements,a double-layer zigzag antenna with the overall size of 7.8×13.5×1.2 mm3 is designed in this thesis.The antenna can transmit and receive signals of two bands simultaneously by means of electromagnetic coupling effect.The antenna avoids cross polarization and has better directional characteristics.The central frequencies of the top and bottom microstrip lines of the antenna are 5.18 GHz and 5.58 GHz,respectively.The gain of the antenna is 0.47 dBi and 0.84 dBi,and the bandwidth of the antenna is 520 MHz and 230 MHz under-7.5 dB echo loss.Through the simulation and analysis of HFSS software,it is found that the antenna has good impedance and directional characteristics.Finally,Li2Mg2(WO4)3 material is used as the matrix(εr=7.72,tan δ=0.000203)and a miniaturized LTCC antenna with the size of 7.8×13.5×1.2mm3 is fabricated by LTCC technology.Through some structural adjustments,the antenna has a wider frequency band,compromising the relationship between antenna size and other performances.The influence of sintering temperature on antenna performance during antenna fabrication is also studied.Compared with the simulation data,the antenna basically meets the design requirements. |
