A low-profile wideband antenna array with wide-scan ability

Date

2023-4-03

Author

Bakan, Tutku

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

269
views

543
downloads

Cite This

An innovative planar wideband array of antennas with wide scan capability and microstrip patches as elements is presented in this thesis. A cavity is positioned on the ground plane to attain wideband operation without increasing the antenna profile. The array is linearly polarized antenna array. It has a very low profile and it is capable of scanning up to 45° at principal planes. The array’s active VSWR (Voltage Standing Wave Ratio) is under 2, and its bandwidth is 21.5%. The connectors and substrate used for the antenna have been selected for ease of measurement and fabrication of the printed circuit board. Specifically, 50 Ω SMP (Sub-Miniature Push-on) connectors are used and the substrate has a relative permittivity of 3 at 10 GHz. At the highest frequency of operation (11.1 GHz), the dimensions of the unit cell are 0.5λ0 x 0.5λ0 x 0.13λ0. The 16x16 element array antenna is fabricated and connectorized. The S-parameters are measured using a Vector Network Analyzer. Close results with the unit cell simulation results are obtained. The antenna operates in 8.92-11.1 GHz band with VSWR below 2 and has a scan capability of ±45° at E-, H- and D-planes. As expected, as the number of elements in the measured array increases, the results become more similar to the unit cell simulation results. The element radiation patterns and the directivity are measured in near-field systems by employing both planar and spherical measurements. In addition to the main focus of the thesis, a novel dual-polarized, low-profile, hybridfed antenna element is also presented for planar phased arrays. Hybrid feed consists of an aperture coupled feed for one polarization and a probe feed for the other polarization. The bandwidth of aperture coupled feed is extended by splitting the feed line into two lines and the bandwidth of the probe feed is increased by utilizing a matching network. This element has a low active VSWR, below 2.5:1, for each polarization port and allows for a wide operation band of 8.8-11.1 GHz with scanning capabilities of 50°, 50° and 75° in its E-, H- and D-planes for both ports. The design of this element is simple and efficient, composed of a set of vias that reduce highorder mode propagation and four Astra MT77 layers. The hybrid feeding approach improves the isolation between the ports, better than 10 dB when the array scans to 0°. The low-profile design of this element makes it suitable for conformal phased array applications.

Subject Keywords

wideband, wide-scan, low-profile, dual-polarized

URI

https://hdl.handle.net/11511/102789

Collections

Graduate School of Natural and Applied Sciences, Thesis