Broadband double circular polarization feed source of radio heliograph

Abstract

The invention discloses a broadband double circular polarization feed source of a radio heliograph. The broadband double circular polarization feed source is applied to a low-frequency array paraboloid of a new-generation centimeter-decimeter wave radio heliograph. The heliograph is composed of 40 single reflecting surface antennas with the frequency band of 0.4GHz to 2GHz and 60 single reflecting surface antennas with the frequency band of 2Ghz to 15GHz and has the advantages of being high in space, high in frequency, high in time resolution and the like. When the frequency band is in a range of 0.4GHz to 2GHz, determination is made by physical properties of an observed object, and the heliograph needs to have a comprehensive imaging capacity in a broadband range. The feed source is an important component of an analog receiving system at the front end of the heliograph. The feed source used by a current project is novel in shape and small in size and reduces shielding of a reflecting surface in the whole broadband range so that efficiency of the antennas can be greatly improved. A standing wave of the tested feed source is smaller than 1.5, an axial ratio is smaller than 1.5dB, and a phase center is not changed along with frequency and is basically unrelated to the frequency. The broadband double circular polarization feed source of the radio heliograph is simple in structure and reliable in quality, and electric performance is good in stability.

Description

1) Technical field [0001] The invention belongs to the technical field of radio and radio astronomy, in particular to a broadband feed source installed on a reflective surface. 2) Technical background [0002] The low-frequency band of the new generation of centimeter-decimeter wave radioheliograph is composed of 40 antenna feed systems, 40 sets of analog receivers and 40 digital receivers. The feed source in the antenna feed system is an important part of the front-end receiving system of the heliograph, and it is also one of the difficulties in the design of the whole system. Determined by the physical properties of the observation target, the heliograph needs to continuously observe the sun with high time, high space, and high frequency resolution, and has comprehensive imaging capabilities in a wide frequency band. The feed pattern should meet the requirements for the irradiation of the reflector, usually taking into account the antenna gain and the side lobe level, and...

AI Technical Summary

Problems solved by technology

For the log-periodic antenna, when the operating frequency band is very wide, the problems and defects of this antenna are: the size of the antenna is very large, if it is added to the reflector, the efficiency of the antenna feed system will be reduced, and the phase center will be easily It moves with the change of frequency; due to its structural characteristics, the planar helical antenna and the conical helical antenna can only achieve single-rotation reception, and cannot receive dual circularly polarized waves at the same time, so they are not suitable for the feed source required by the heliograph

Because if the feed source of the direct dual circularly polarized output signal cannot meet the frequency range requirement of 5 octaves of the low frequency part

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