Investigation of Virtual Array Antennas With Adaptive Element Locations and Polarization Using Parabolic Reflector Antennas

Pour, Z. Allahgholi; Shafai, L.

doi:10.1109/tap.2012.2225818

Cited by 14 publications

(13 citation statements)

References 7 publications

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“…As discussed earlier, the electronic DPCA is made possible by employing an over-moded primary feed in order to preferentially illuminate different parts of the aperture antenna to effectively shift the phase-center location away from the physical center of the aperture. The detail of the technique was published by the authors in [7] with a dual-mode feed operating at the -and -type modes. However, the cross polarization of the symmetric reflector antenna inevitably increases, due to the asymmetric nature of such a primary feed, which now contains an extra asymmetric mode, along with the symmetric dominant mode.…”

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

“…However, the cross polarization of the symmetric reflector antenna inevitably increases, due to the asymmetric nature of such a primary feed, which now contains an extra asymmetric mode, along with the symmetric dominant mode. As a representative example, the normalized secondary radiation patterns of the symmetrical-cut reflector defined in Section II and fed by (1), with , and [7], are shown in Fig. 2(a).…”

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

“…The copolar component is axial, as expected, and the cross-polar discrimination is quite poor at the planes of 0 and 45 . As shown in [7], the phase-center displacement along the negative -axis can be obtained by applying a phase shift between the modes. That is, the phase-center location will be at the point and cm, for the .…”

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

“…It should be noted that the phase-center location of an antenna is defined as the effective source of radiation. To locate this, the coordinate origin of the antenna under study is displaced to the point such that uniform phase patterns around the main beam are formed [7]. For clarity, the secondary far-field phase patterns are plotted in Fig.…”

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

“…Later, the concept was well elucidated by the authors in [7] and [8], where the polarization control of the over-moded feeds was generalized and shown that the phase center can be displaced in any plane, as desired. The antenna parameters, such as gain, sidelobe level (SLL), and phase-center locations, were also addressed by the authors in Manuscript [9] with a dual-mode dual-polarized primary feed for offset reflector antennas.…”

Section: Introductionmentioning

confidence: 99%

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Improved Cross-Polarization Performance of a Multi-Phase-Center Parabolic Reflector Antenna

Pour

Shafai

2014

Antennas Wirel. Propag. Lett.

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This letter addresses the cross-polarization properties of electronically controlled multi-phase-center parabolic reflector antennas, illuminated by over-moded primary feeds. Due to the presence of the higher-order modes in the primary feed, the secondary cross-polarization levels deteriorate in the case of symmetric reflector antennas. As for the offset reflectors, the primary multimode feed required to displace the phase-center location may produce a significant crosstalk in the orthogonal polarization. It is shown how one can improve the cross-polarization performances of aforementioned adaptive antennas, which are capable of providing axial beams while their phase-center locations are displaced. The conventional array technique with a simple signal processing is used for the symmetric case, whereas a trimode primary feed is employed for the offset case.

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Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

Section: A Symmetric Prime Focus Reflector With a Dual-mode Primary mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved Cross-Polarization Performance of a Multi-Phase-Center Parabolic Reflector Antenna

Pour

Shafai

2014

Antennas Wirel. Propag. Lett.

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Applications of trimode waveguide feeds in adaptive virtual array antennas

Pour

Shafai

2015

Radio Science

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This paper presents the formation of an adaptive virtual array antenna in a symmetric parabolic reflector antenna illuminated by trimode circular waveguide feeds with different mode alignments. The modes of interest are the TE 11 , TE 21 , and TM 01 type modes. The terms TE and TM stand for the transverse electric and transverse magnetic modes, respectively. By appropriately exciting these modes and varying the mode orientations inside the primary feed, the effective source of radiation is displaced on the reflector aperture, while the resulting secondary patterns remain axial. Different antenna parameters such as gain, cross polarization, and phase center locations are investigated. It is demonstrated that the extra third mode facilitates the formation of symmetric virtual array antennas with reasonable cross polarization discriminations at the diagonal plane.

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