Research On Miniaturization Of The Quadrifilar Helical Antenna

With the rapid development and widely use of global satellite navigation system,the demand for miniaturized antennas is becoming increasingly urgent for a variety of portable and bayonet devices.Microstrip antenna and quadrifilar helix antenna are the most common antenna types in the field of satellite navigation.Compared with the microstrip antenna,quadrifilar helix antenna has its advantages of wide beam,heart-shaped pattern and good front-back ratio.But the size is too large to develop in low frequency band.In order to meet the needs of miniaturization,researching on the miniaturization of the antenna has important significance.The main works of this paper are as follows:1.The miniaturization methods of antenna were especially studied,the initial size of antenna is calculated by the calculation formula of antenna structure.The ceramic medium is added to the antenna model and the spiral arm is folded.The traditional method of folding arm is improved by simulation.After the improvement,the original radial arm folded rotate a certain angle,extended the part of the folding arm to the bottom of the antenna,and connected the next coaxial feed external conductor to complete the miniaturization design.The final size is 8.6mm×19.8mm,the volume is reduced significantly compared with traditional air-loaded quadrifilar helix antenna.2.To improve the structure of the Wilkinson power splitter,the feeding network is printed on double substrate with the bottom 180 degree power divided and the upper 90 degree power divided.Ultimately,the four-way signal with equal amplitude and 90 degrees phase difference were achieved by connecting the up and down layers together by the probe.The feeding network’s area is reduced by half,with diameter of 45mm.3.Radius of error is determined by the analysis of simulation results and the error of models.The results indicate that the parameters of the antenna can achieve excellent performance,including good radiation characteristics,compact structure,small size and the needs of miniaturized receiving equipment.The problem of poor performance of small-scale radiation is solved and the application requirements of some small-sized transceiver equipment is satisfied by the research of miniaturized quadrifilar helix antenna,which can provide theoretical basis for the development of miniaturized antenna in the future.