Abstract
In this paper, we propose a polarization-selective electromagnetic (EM) transparent mesh-type E-shaped antenna unit-cell in a shared aperture. The proposed antenna unit-cell, which can be expanded to a larger array in a modular way, has one S-band antenna on the upper layer and nine X-band antennas on the lower layers. The simple E-shaped structure, which has a low profile with a good bandwidth, is used for the antenna elements. However, due to the limited aperture size of the stacked configuration, the lower-layer elements can be physically blocked by the upper-layer element. To reduce this blockage effect, the S-band element is rotated 90 degrees with respect to X-band elements so that the polarizations between the S- and X-band elements are perpendicular to each other. Moreover, to minimize performance degradation due to the blockage effect, a mesh structure is applied for S-band elements for EM transparent characteristics, thereby improving EM transparency from −30 dB to −1.5 dB. The extended via cavity wall is also employed outside the nine X-band elements to minimize the mutual coupling and to reduce antenna size. To confirm the effectiveness of the proposed design, the proposed antenna unit-cell is fabricated, and the radiation characteristics are measured, in a full anechoic chamber. The average bore-sight gains in the S- and X-band are 5 dBi and 4.5 dBi, respectively. The results confirm that the proposed design is suitable for shared-aperture radar applications.
Highlights
Dramatic advances in the latest active electronically scanned array (AESA) technologies have resulted in the development of high-performance multi-function radars (MFRs) for military ship radar systems [1,2,3,4,5]
Various frequency bands are applicable to military ship radar systems, the S-band and X-band are important and are widely adopted [10]
The S-band radar is often employed for the surveillance of targets, whereas the X-band radar is used for the accurate tracking of targets [11,12]
Summary
Dramatic advances in the latest active electronically scanned array (AESA) technologies have resulted in the development of high-performance multi-function radars (MFRs) for military ship radar systems [1,2,3,4,5]. As the space efficiency increases, the elements on the lower layer are inevitably blocked by the elements on the upper layer due to the decreased distance between elements This physical blockage leads to a deterioration of the electromagnetic radiation characteristics of the antenna [21]. It is difficult to apply this solution for space-efficient shared-aperture arrays, since there are many restrictions on the antenna shape and configuration of the upper and lower layers, which lead to the degradation of the array characteristics. We propose the electromagnetic (EM) transparent E-shaped antenna, which consists of one S-band element stacked on top of 3 × 3 X-band elements in a shared aperture These ten antenna elements form a basic unit-cell, which can be expanded to a larger array in a modular way. The results demonstrate that the proposed mesh structure of the E-shape antenna can minimize the blockage effect of the upper layer and the extended via cavity wall can improve the mutual coupling effect with a simple via hole manufacturing process
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