Mechanical stress induces a scalable circularly polarized LEO satellite antenna with Quadrifilar spiral

Abstract

<abstract> <p>This paper investigates a left-hand circularly polarized (LHCP) antenna and a right-hand circularly polarized (RHCP) antenna on LEO Satellite, which is based on the phase-tuning metasurface. We overcome its inherent limitations in size, weight and power, and designed a high-gain, ultra-lightweight, scalable antenna for small satellite communications. The antenna can generate continuous and large tunability of subwavelength, with low-Q resonators. The simulated and experimental results verify that different capacitance and inductance modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The maximum gain of the normal position within the angle of the uplink and downlink is 4~9 dBi higher than that of the ordinary polarized antenna. In addition, the design method proposed to this article is superior to the reference system in terms of impedance bandwidth, axial ratio bandwidth, and operation frequency. The performance achievements of this paper are implemented within the bandwidth of 3 MHz of uplink and downlink, such as impedance bandwidth is 3 MHz with impedance of 50, axial ratio bandwidth is 2.5 MHz, operation frequency of uplink is 240–243 MHz, downlink is 320 MHz and 401 MHz, and the voltage standing wave ratio (VSWR) is less than 2 dB which is so called S parameter, the above parameters can meet the performance index design requirements.</p> </abstract>

Micro-Motion Parameter Extraction of Multi-Scattering-Point Target Based on Vortex Electromagnetic Wave Radar

“…Then, the unit vector in the LOS direction is n LOS = n x , n y , n z T = (sin θ r cos ϕ r , sin θ r sin ϕ r , cos ϕ r ) T , the velocity vector of the scattering point P along the LOS is v = v x , v y , v z T = v • n LOS , the arbitrary angular velocity is ω = ω x , ω y , ω z T = ω • n LOS , and its polar coordinate in the target coordinate system is r p , θ 0 , ϕ 0 T . There are many ways to generate VEMW at present, such as nested double-arm helical antennas [21], helical phase plates [22], metasurfaces [23,24], etc. In this paper, the singletransmit multiple-receive method is used to generate VEMW carrying the mode of l through the Uniform Circular Arrays (UCA).…”