Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy
Chin. J. Mech. Eng.
Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy
Shuxin ZHANG 0 1
Jingli DU 0 1
Wei WANG 0 1
Yali ZONG 0 1
Xinghua ZHANG 0 1
0 Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology , Beijing 100094 , China
1 Key Laboratory of Electronic Equipment Structure Design of Ministry of Education, Xidian University , Xi'an 710071 , China
A well-designed reflector surface with high beam pointing accuracy in electromagnetic performance is of practical significance to the space application of cable mesh reflector antennas. As for space requirements, circular polarizations are widely used in spaceborne antennas, which usually lead to a beam shift for offset reflectors and influence the beam pointing accuracy. A two-step structural design procedure is proposed to overcome the beam squint phenomenon for high beam pointing accuracy design of circularly polarized offset cable mesh reflectors. A simple structural optimal design and an integrated structural electromagnetic optimization are combined to alleviate the beam squint effect of circular polarizations. It is implemented by cable pretension design and adjustment to shape the offset cable mesh surface. Besides, in order to increase the efficiency of integrated optimization, an update Broyden-Fletcher-Goldfarb-Shanno (BFGS) Hessian matrix is employed in the optimization iteration with sequential quadratic programming. A circularly polarized offset cable mesh reflector is utilized to show the feasibility and effectiveness of the proposed procedure. A high beam pointing accuracy in order of 0.0001º of electromagnetic performance is achieved.
Cable mesh reflector antennas; Structural design; Beam squint; Beam pointing accuracy
-
In recent years, the stringent requirements on large space
reflectors become demanding for high electromagnetic
performance [
1
]. As for space applications, circular
polarizations are usually used in spaceborne antennas. With
circularly polarized feeds, there exists a beam squint
phenomenon in offset reflector antennas [
2
]. The squint angle,
which is manifested by a small beam shift of the radiation
pattern in the plane perpendicular to the principal offset
plane, can significantly affect the beam pointing accuracy.
As one of the most widely used space antennas, cable mesh
reflector antenna has attracted much attention due to its
advantages of large diameter, light weight, and reasonable
cost [
3
]. Similarly with the smooth solid reflectors, the
beam squint phenomenon can also be observed in offset
cable mesh reflector antennas with reflecting mesh leakage
[
4, 5
]. The beam squint angle should be taken into account
for space applications such as satellite communications,
deep-space telemetry, and radio astronomy [2], which
concentrate more on beam pointing accuracy. With the
stringent requirements on space reflector antennas, the
compensation technology to overcome the antenna pattern
degradation including beam squint to achieve high pointing
accuracy becomes more demanding [
6
].
Since the simple formula which accurately predicts the
squint angle in circularly polarized offset reflectors was
proposed by ADATIA and RUDGE [
7
], the beam squint
phenomenon and its compensation method have attracted
many authors’ interests. A squint compensation method by
properly tilting the feed to make the interpreted angle
between the incident beam and the radiated beam zero is a
natural choice for symmetrical reflectors with off-focus
feeds [
8
]. A squint free approach for symmetrical dual
reflector antennas is also proposed by properly choosing
be achieved in the antenna structural design. This
technology not only can compensate the beam squint angle of
circular polarizations, but also can produce a well-designed
cable mesh reflector with on-focus feeds. Comparing with
the compensation methods proposed by electromagnetism
designers, the limited weakness of aforementioned
methods can be overcame.
This paper is organized as follows. Section 2 of this
study outlines the procedure of the two-step structural
design technology. In this technology, an update
BroydenFletcher-Goldfarb-Shanno (BFGS) Hessian matrix is
employed to increase the efficiency of optimization
iteration. In section 3, a circularly polarized offset cable
mesh reflector is utilized to show the feasibility and
effectiveness of this procedure with an on-focus feed to
achieve high beam pointing accuracy in electromagnetic
performance. The major achievements are summarized in
section 4.
geometrical parameters [
9
]. Furthermore, XU and
RAHMAT-SAMII [
2
] summarized the beam squint
compensation methods, and proposed a compensation
technology by optimally displacing circularly polarized
feeds in the perpendicular plane to obtain high beam
pointing accuracy. However, these methods in Refs.
[
2, 7–9
] are presented from the simple electromagnetic
disciplinary, and they are just practical for undistorted
r (...truncated)