The Research Of Performance Of Plasma Whip Antenna And Closely Spaced Yagi Antenna For Meter Waves

In this thesis, the reconfigurability and stealth performance of plasma whip antenna are studied, as well as closely spaced Yagi antennas for meter waves. Based on these research, the two-folded plasma Yagi antenna for meter waves is presented for the first time, and this provides theoretical and technological support for the wide-band dual-frequency, dual-polarization, cross-polarization receiving, meter wave plasma Yagi antenna systems, and also provides an effective tool for detection of the hard-to-detect targets and especially for protection against the heavy EM attack in VHF range.According to the result of this thesis, when incident EM wave frequencyωbelow plasma frequencyωp, plasma presents'metal-like'characteristic and can form plasma antenna which is replacement of metal antenna, however, it is against stealth. By changing plasma density to makeωp belowω, stealth performance and self-protection against high EM interference are realized. If well designed, two-folded Yagi antenna, used in the range of 100MHz and 300MHz, can achieve excellent impedance matching to the 50Ωtransmission line, with directivity higher than 5.4dBd, while the space between elements is only 0.02λ, thus greatly satisfying the needs of trends nowadays which require antennas to be much smaller.