Beam squint in circularly polarised offset-reflector antennas

Adatia, N.; Rudge, A. W.

doi:10.1049/el:19750396

Cited by 34 publications

(17 citation statements)

References 1 publication

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“…8 shows radiation pattern with a pin height of 0 mm (i.e., without pin). In this case a beam squint of 0.1 • (from bore sight) was observed, which approximately matches with the theoretical value of 0.11 • as derived by Rudge's formula [4]. For the same offset reflector antenna, when the pin height of the matched feed was adjusted to 6mm, a squint-free radiation pattern was resulted as shown in Fig.…”

Section: Resultssupporting

confidence: 86%

“…The beam squinting occurs when two mutually orthogonal linear cross polar components add to a co-polar circular component [2]. The magnitude of the beam squinting can be estimated by a mathematical formula as derived by Rudge and Adatia [4]. Beam squinting displaces the main beam, reduces the gain [3], limits the accuracy in case of radio astronomical observations [5], and degrades the performance of the overall system.…”

Section: Introductionmentioning

confidence: 99%

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Removal of Beam Squinting Effects in a Circularly Polarized Offset Parabolic Reflector Antenna Using a Matched Feed

Sharma¹,

Pujara²,

Chakrabarty³

et al. 2009

PIER Letters

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Abstract-This paper presents the design of a tri-mode matched feed horn to remove the beam squinting effects in a circularly polarized offset parabolic reflector antenna. In a conical horn, three modes i.e., TE 11 , TM 11 and TE 21 are combined in proper amplitude and phase proportion to obtain a tri-mode matched feed configuration. The proposed tri-mode horn is then used as a primary feed device to illuminate the circularly polarized offset parabolic reflector antenna. The simulated data on radiation characteristics of the offset reflector are used to estimate the magnitude of beam squinting and the results are compared with that of a conventional potter horn fed offset reflector. The experimental results on secondary radiation pattern are also incorporated in the paper.

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Section: Resultssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Removal of Beam Squinting Effects in a Circularly Polarized Offset Parabolic Reflector Antenna Using a Matched Feed

Sharma¹,

Pujara²,

Chakrabarty³

et al. 2009

PIER Letters

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“…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].…”

Section: Introductionmentioning

confidence: 99%

“…However, these methods in Refs. [2,[7][8][9] are presented from the simple electromagnetic disciplinary, and they are just practical for undistorted reflectors in the nominal state for preliminary design. In actual engineering, space reflectors including cable mesh antennas are easily susceptible to surface distortion under thermal load and other impacts, which enlarge the beam squint angle and seriously affect the beam pointing accuracy.…”

Section: Introductionmentioning

confidence: 99%

Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy

Zhang

et al. 2017

Chin. J. Mech. Eng.

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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.

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“…1). Adatia and Rudge [3] derived a simple formula that accurately predicts the squint angle for a single offset parabolic reflector with an on-focus circularly polarized feed (1) where is the tilt angle of the feed, is the focal length of the paraboloid (Fig. 1), and is the wavenumber in free space.…”

Section: Introductionmentioning

confidence: 99%

A Novel Beam Squint Compensation Technique for Circularly Polarized Conic-Section Reflector Antennas

Rahmat‐Samii

2010

IEEE Trans. Antennas Propagat.

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Beam squint generally exists in offset reflector antennas with circularly polarized feeds. It is manifested by a small beam shift of the radiation pattern in the plane perpendicular to the principal offset plane, which can significantly affect the beam pointing accuracy. In this paper a practical and widely applicable compensation technique for the beam squint is proposed. Simulation results show that a small lateral feed displacement in the perpendicular plane can effectively minimize or eliminate the linear phase shift caused by the depolarization effect, thus compensating for the beam squint effect. This is in practice very useful for offset reflector antennas where the previously suggested method based on feed tilting may not be proper. A simple formula is derived to quickly estimate the optimal feed displacement for both right-and left-hand circularly polarized feeds. Three representative examples: a single offset parabolic reflector, a suboptimal offset Cassegrain reflector, and an axially symmetric Cassegrain reflector with an off-focus feed, are presented to validate the proposed method. Satisfactory results are achieved for all three examples.

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Beam squint in circularly polarised offset-reflector antennas

Cited by 34 publications

References 1 publication

Removal of Beam Squinting Effects in a Circularly Polarized Offset Parabolic Reflector Antenna Using a Matched Feed

Removal of Beam Squinting Effects in a Circularly Polarized Offset Parabolic Reflector Antenna Using a Matched Feed

Two-step Structural Design of Mesh Antennas for High Beam Pointing Accuracy

A Novel Beam Squint Compensation Technique for Circularly Polarized Conic-Section Reflector Antennas

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