Study On Metric Wave Broad-band Plasma Antenna Theory And Its Key Device

Metric wave, corresponding to the VHF(Very High Frequency) is an important operating band of radio station, television station broadcast, aviation and maritime. With the rapid development of communication technology, the frequency hopping range of modern military tactical radio communications is getting wider, and in civilian the channel capacity continued to expand, the communication equipment trend to be broadband. These new trends make increasingly strong demand for broadband Meter wave antenna as an important device in wireless communication system.Since the plasma antenna has advantages that traditional metal antennas do not have, such as light weight, stealth, and reconstruction, it can improve the performance of the radar stealth of military equipment in the military, and it can better control the antenna radiation characteristics on the civilian, which means a broad application prospects.This paper focuses on a study of VHF broadband plasma antenna. In the theory of VHF broadband plasma antenn, this paper do research for VHF plasma excitation device, VHF plasma frequency control method, a wide load plasma harmonic filtering method, and UHF signal extraction methods, and gives related design mechanism and methods. Depend on these, I design dual-band VHF plasma antennas on 65 ~ 78,108 ~ 121 MHz, and do physical processing tests for them. The results show that the measured values, simulation values, and theoretical design values are consistent, which prove the correctness of the proposed design theory and methods.Based on the former work, we proposed two possible methods in order to further optimize the antenna’ working band. Through simulation we found that the antenna’ working band can be expand to 65~100MHz(1.53 octaves) by the two methods. One is through increasing the input RF power plasma frequency antenna to improve the frequency of antenna to spread spectrum. We found that the demand for RF power is 65 k W through theoretical analysis and calculation, in which the energy consumption is too large and works hard to achieve; the other is to adjust the antenna structure size, trimming the plasma center oscillator and increase metal sleeve 24 cm, which is proved by simulation. The antenna of new size is being processed.Currently, in terms of electromagnetic compatibility, research of plasma antennas at home and abroad are mostly focusing on narrow band antennas. Whereas in this paper, it involves the research and development of broadband plasma antenna, in which case the plasma antenna electromagnetic compatibility is very important. In this paper, the EMI and electromagnetic compatibility problems such as the instrument overload, harmonic distortion in measurement equipment, harmonic noise in the communication band which generated by RF excitation source of broadband VHF antenna plasma has been analyzed. These problems are not valued in narrowband plasma antenna research work.On this basis, for special applications of wide range variable load in plasma antenna, wide load plasma harmonic filtering methods has been studied. Appling the design of the filter according to the law to the actual antenna system, the instruments overload and harmonic distortion in measurement equipment has been solved. Interference harmonic amplitude in the communication band is inhibited effectively. For typically six harmonics(81.36MHz), the degree of inhibition is 23.4dB.In addition, the experiment has proved that the coupling path of electromagnetic interference signal will amplify the harmonic interference, and this problem is difficult to solve by frequency shared filtering. So it is necessary to optimize the conventional RF excited plasma antenna system.In terms of the optimization of plasma antenna system, all-optical plasma antenna system is introduced. The system operates under the all-optical mode, ensuring electromagnetic compatibility for plasma antenna system fundamentally. A study to its key equipment-continuously high repetition rate pulse high voltage source is launched. I have completed the transition from experimental system to equipment prototype of the pulse source by industrial design, functional design, cooling system transformation, internal cable design, etc. During this work, a control software system of the pulse source is developed independent.