Research Of Miniaturized And Wideband Shortwave Antenna

In modern wireless communication system, short-wave communication plays an extremely important role. As the port to receive and transmit radio waves, its performance is determining to the entire system. For shortwave antenna, on one hand, the antenna size in this spectrum is generally larger due to the longer wavelength (10m-100m).It is a big obstacle for the shortwave antenna’s widely development. On the other hand, modern wireless communication system also has a high requirement for the band width of shortwave antenna. Under the project "Study of miniaturized and wideband Shortwave Antenna" that Liaoning Putian Digital Company cooperated with Dalian Maritime University Antenna and Microwave Institute, bases on the lab conditions, the author does some research and finishes this paper.On the basis of summarizing the predecessors’achievements, the author deeply studies the shortwave antenna miniaturization and broadband technology, and does a large amount of simulation computation. For different antenna structures, the author puts forward different optimization methods. The main work of the paper is as follows:(1) A varying pitch two-wire NMHA (Normal-mode helical antenna) is designed based on the traditional method for the NMHA. On the basis of retaining the miniaturization characteristic, the author optimizes the structure of helical antenna to make its bandwidth wider, making its bandwidth wider. After a large number of simulation and parameter optimization for the structure, finally the antenna achieves a good matching from2MHZ to30MHZ. Compared with the existing shortwave antenna, its volume has a certain advantage.(2) In order to improve the short-wave communication blind zone flawed, the author designs a NVIS (Near Vertical Incidence Sky wave) semi-ring antenna, and puts forward a new method of MATLAB and HFSS software’s joint simulation. Using genetic algorithm to optimize the value of lumped components loading in the antenna, and by setting up the passive matching network in ADS, eventually the standing wave ratio is less than2from2MHz to30MHz, EBG structure is used as antenna’s reflector to improve its direction effectively.(3)The author designs the NIC (negative impedance converter) as the active matching network to broaden monopole’s bandwidth, selects2sc3355triode as the core device of the float negative impedance converter, and processes and tests the converter. Finally the purpose is reached by using negative capacitor to offset the large reactance of monopole.