No abstract

In this study, a new spiral dual-band antenna integrated with an optical system for a small CubeSat spacecraft was proposed. It is challenging to design an antenna with a limited space on a CubeSat platform. To improve the space utilization, an antenna was designed based on the concept of not occupying the sides of the CubeSat. A feature of the proposed antenna system is its compactness, dual-band operation in the L-and S-bands, and possibility of integration with spacecraft cameras. As a result of the study, reflection coefficients of -18 dB and -23 dB and gain of 6.8 dBi and 7.4 dBi, respectively, were achieved at resonant frequencies of 1.7 GHz and 2.45 GHz. The conical shape of the spiral antenna allows the optical system to increase the coverage area, and a simple deployment system with feedback ensures the mission safety. These properties make the proposed antenna suitable for CubeSat systems.INDEX TERMS CubeSat antenna, dual-band antenna, Earth observation, helix antenna

No abstract

The CubeSat concept has become very popular with both university groups and researchers, space agencies, governments and companies. CubeSat offers a fast and affordable way for a wide range of stakeholders to be active in space. Due to the high degree of modularity and widespread use of off­the­shelf commercial subsystems, CubeSat projects can be prepared for flight much faster than using traditional satellite schedules usually within one to two years. In this paper, we have considered a model of an S and X band patch antenna for CubeSat nanosatellites in the field of Earth remote sensing (ERS). The antenna dimensions were determined and designed according to the dimensions of the small spacecraft. The shape of the emitting part was formed using a geometric fractal with an anisotropic structure. Using the CST Microwave Studio software package, the electro­dynamic, frequency characteristics and directional properties of the antenna were determined. The results of computer simulations demonstrate that the developed antenna concept has a multi­band property and meets all the parameters that are necessary for receiving and transmitting data in the S and X bands. It was also found that the anisotropic fractal structure allows the antenna to have several operating frequencies.

The inequality of the universal gas constant of the difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume is proved. The falsifications of using the heat capacity of a gas at constant pressure, false enthalpy, Poisson adiabat, Laplace sound speed, Hugoniot adiabat, based on the use of the false equality of the universal gas constant difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume, have been established. The dependence of pressure on temperature in an adiabatic gas with heat capacity at constant volume has been established. On the basis of the heat capacity of a gas at a constant volume, new formulas are derived: the adiabats of an ideal gas, the speed of sound, and the adiabats on a shock wave. The variability of pressure in the field of gravity is proved and it is indicated that the use of the specific coefficient of ideal gas at constant pressure in gas-dynamic formulas is pointless. It is shown that the false “basic formula of thermodynamics” implies the falseness of the equation with the specific heat capacity at constant pressure. New formulas are given for the adiabat of an ideal gas, adiabat on a shock wave, and the speed of sound, which, in principle, do not contain the coefficient of the specific heat capacity of a gas at constant pressure. It is shown that the well-known equation of heat conductivity with the gas heat capacity coefficient at constant pressure contradicts the basic energy balance equation with the gas heat capacity coefficient at constant volume.