V.V. Kakshin - Engineer, JSC «Corporation «Vega» (Moscow). E-mail: mail@vega.su K.V. Kozlov - Head of Laboratory, JSC «Corporation «Vega» (Moscow). E-mail: mail@vega.su I.Yu. Ryzhov - Research Scientist, JSC «Corporation «Vega» (Moscow). E-mail: mail@vega.su I.I. Ivenkov - Head of Laboratory, JSC «Corporation «Vega» (Moscow). E-mail: mail@vega.su A.B. Vetrov - Engineer, JSC «Corporation «Vega» (Moscow). E-mail: mail@vega.su

This article shows how the thermal expansion affects properties of slot antennas designed for navigational Doppler radar. This Doppler radar was designed for the spacecraft, which should be landed on the Moon. This leads slot antennas to be used in outer space and affected by its thermal conditions (−200°C - 200°C). Thermal changes of such a big range can change the size of slot antennas, which can affect antennas - properties. The simulation of size changes was made upon slot antenna. The results of simulation are given in this article. Research shows that thermal changes affect main lobe direction, side lobe level, main lobe width and voltage standing wave ratio. Voltage standing wave ration variations are rather small and should not be considered as a source of negative effects for navigational Doppler radar. Also, side lobe level variations are rather small. As far as its value is more than required, there is a necessity of simulation of thermal effects on slot antennas. Main lobe direction variations, caused by outer space thermal conditions, can cause systematic navigational mistakes, but simulation of thermal effects on slot antennas can provide navigational radar with correction factor in order to get rid of the systematic navigational mistakes caused by main lobe direction variations. Main lobe width variations are small. Navigational mistakes, caused by main lobe width variations, are similar to mistakes, caused by moon relief. And moon relief fluctuations are much greater than main lobe variations.

 

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