Shortwave Conformal Antenna Research

The traditional short wave antennas are generally too large and their structures are fixed and unalterable. These kinds of antennas are designed for especial uses without all-purpose characteristic while the condition is shifted, as a result that the antennas are costly to fabricate. Two antennas of short wave, conformal communication line, working at 108 MHZ to 177MHZ and 166 MHZ to 400MHZ, respectively, are presented in this paper. Software CST Micro Wave Studio is employed for simulations of the antenna models. Since a series of lumped elements are used, the bandwidths of the antennas are enhanced and the return losses are reduced. Good input impedance, SWR, radiation patterns of the antennas are also presented. Finally, matched circuits for the antennas are designed. These antennas, with the characteristic of miniature, wide bandwidth, conformal, can be used to vehicle-mounted, sailer-mounted and flight-mounted carriers etc. A method for applications of self-structure antenna (SSA), which has a simple structure, is presented in the paper too. In order to make the SSA to work on different frequency, 19 switches are used in the SSA. We can control the alteration of the structure of the SSA with the 19 switches. We simulate this antenna using CST in a lot of states of the switches, and get the important characteristic of the SSA, such as S11, input impedance, radiation patterns etc. During the simulations, the values of the characteristic are added to a database file including plenty of parameters of the SSA under almost all kind of states of the switches. When the database is built, we can make use of the data to control the switches to work. When a frequency is given, all bands that are fit to the frequency can be distilled from the database by the use of two steps method. The antenna can work in the bands of 500MHZ to 800MHz, with the return loss less than –12dB. This theoretic, nevertheless, offer us a new method to use this kind of antennas.