• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.8
• /
• pp.1622-1630
• /
• 2015

In this study, we used EBG(electromagnetic band gap) reflector to change bi-directional radiation of circular polarization into uni-directional radiation of equiangular spiral antenna. When the height of spiral arm from EBG reflector is 0.07 wavelength of the lowest operating frequency, the axial ratio of the circular polarization was deteriorated. In this paper, we analyzed the magnitude and the time phase difference of $E_{\theta},E_{\phi}$ that generates right hand circle polarization that is co-polarization at +z direction and proposed the improving condition for axial ratio at all related frequency range. As a result, we obtained that the axial ratio was below 3[dB] at range of 3 ~ 10[dB], the gain was improved about 3[dB] with comparison to bi-directional radiation at free space, and $S_{11}$ was below -10[dB] at all related frequency range.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.4
• /
• pp.485-491
• /
• 2014

An Antenna & RF system for a fly-away satcom terminal application on ka-band is presented in this paper. The Fly-away satellite terminal can be moved and operated by two person and adapt automatic satellite tracking system in order to decrease the tracking time. Additionally, for low-power consumption, compact size and light-weight, a dual reflector antenna is constructed using dual-offset gregorian antenna structure. For minimize weight, the reflector of the antenna is made of Magnesium. For low-power consumption and light-weight, the pHEMT MMIC compound devices is utilized. The Electronic Band-Gap(EBG) Low-Pass Filter(LPF) is designed for harmonic rejection. In the receiving part, Low-Noise Block converter(LNB) structure is designed for compact and lightweight. In this paper, fly-away satcom terminal with low-power consumption, compact size and light-weight is described with antenna system and RF system performances. Through the experimentation, fly-away terminal's EIRP is more than 50dBW, G/T is more than $17dB/^{\circ}K$.