V.A. Balagurovsky - Employee, PJSC «NPO Almaz» (Moscow) V.N. Mosalov - Employee, PJSC «NPO Almaz» (Moscow) A.O. Manichev - Ph. D. (Eng.), PJSC «NPO Almaz» (Moscow). E-mail: alex_manichev@inbox.ru A.N. Tyuvaev - Employee, PJSC «NPO Almaz» (Moscow). E-mail: Okean87@mail.ru B.V. Levkin - Employee, PJSC «NPO Almaz» (Moscow) N.S. Kosenkov - Employee, PJSC «NPO Almaz» (Moscow). E-mail: n.kosenkov1@gmail.com

Development of an efficient beam-forming network (BFN) supporting all the necessary operating modes and radiation patterns of a high-gain active phased antenna array (APAA) with due account taken of the architecture and the dimensions of it is an important practical task. The principal technical solutions used in design of the BFN for such an APAA are discussed in this paper. This network should meet the following requirements. In the first place, uniform amplitude distribution must be realized at the outputs of the BFN in order to provide high gain. Secondly, it is often necessary to create sum and difference patterns simultaneously and provide high stability of the transmission coefficients from the input of the network to its outputs. Also, it is desirable to provide the ability of further modification of the BFN for transformation of the APAA to a digital antenna array. In order to realize a uniform amplitude distribution at the inputs of all APAA radiators a combined parallel-and-serial feed design was adopted. The parallel feed consists of the main transmission line in the form of a rectangular waveguide and simple coupling elements in the form of the inner conductors of coaxial transmission lines introduced into the main line. This construction provides a necessary amplitude adjustment range and good match at the input of the parallel feed network providing that the distances between the coupling elements are optimized. The monopulse mode is implemented through the use of four magic tees arranged in the classic scheme proposed by R. Page. The three outputs of the BFN provide traditional sum and two difference channels, and the fourth output can be used for APAA diagnostics purposes. The ability of transformation of the APAA to a digital array was realized with the help of additional hybrids switching the outputs of APAA modules to the analog-to-digital converters inputs by changing phase distribution in the modules. Thus, the developed geometry of the coupling element and the optimization of the serial feed network significantly improved the per-formance of the BFN. That was confirmed by simulation and experimental results.

 

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