I.Yu. Rijov

The results of a circularly polarized L-band primary antenna design are presented. The base of this antenna is a patch-antenna fed by a microstrip branchline λ/4-coupler. For forming the required radiation pattern extra ring screen was added to the construction of the antenna. The main advantage of this antenna in comparison with the horn primary antenna is the more simple construction. The design was carried out by means of the CST Microwave Studio program. The frequency characteristics of the primary antenna were obtained for two cases: the primary antenna being worked with reflector and the primary antenna being worked in free space. For verifying the theoretical results an antenna breadboard model was fabricated and tested. The measured results in the frequency band of 40 MHz are next: VSWR is less than 1,3, the isolation is greater than 17 dB and the axial ratio is not smaller 0,8 in the direction of maximum radiation pattern. The measured characteristics have good coincidence with the theoretical characteristic.