BROADBAND DOU BASED ON ROTHMAN'S PRINTED LENS FOR MULTIBEAM ANTENNA ARRAYS
Abstract
The most well-known beamforming device (DOU) (for linear and flat MAR) is the Rothman
lens, which is of great interest because it allows you to form a fan of MAR rays in a wide spatial
sector of angles (wide-angle scanning), has a fairly high efficiency and MAR with a lens Rothman
has a low level of side lobes. Another advantage of the MAR with a Rothman lens is the weak dependence
of the position of the rays in space on frequency, in contrast to the MAR with a Butler
matrix DOE, in which, at a high efficiency (theoretically 100%), the position of the rays depends
on the frequency. However, the previously developed analogs of the Rothman lens are large and
require additional components in the design, which affects the transmission coefficient of the lens
in the operating frequency range from 2 GHz to 20 GHz and the consistency of the device with
other components of the transceiver equipment. It follows that the study and modernization of lens
structures in relation to multibeam antenna arrays (MAR) is a topical topic for research. The purpose
of the work is to propose a method for calculating the Rotman lens, modernize the lens design,
make a lens model and conduct an experimental study of the lens in order to obtain constructive
methods for optimizing the characteristics of the Rotman lenses for use in MAP in the frequency
range from 2 GHz to 20 GHz. In the results of the article, the dimensions of the lens, the
mass of the lens, the transmission coefficient, and the simplicity of the design are estimated incomparison with the previously developed analogues. A technique for calculating the geometry of
a Rotman lens is proposed, the SWR of a printed Rotman lens is experimentally studied on a vector
network analyzer, constructive methods are obtained for optimizing the characteristics of Rotman
lenses for use in multibeam antenna arrays. A model of a broadband Rotman lens in microstrip
design with a maximum SWR of 1.3 (S21) in the operating frequency range from 2 to 20 GHz was
made, the lens size was 150x100, and the lens weight was 0.4 kg. According to these parameters,
the Rothman lens surpasses the analogues developed earlier.
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