Phased array antenna element for automotive radar application
Nemati, Mohammad Hossein (2014) Phased array antenna element for automotive radar application. [Thesis]
In this thesis work, a design of reliable antenna front-end for W band automotive radar is studied and the problems and considerations associated with phased array antenna design at W-band are addressed. Proposed phased array antenna consists of on chip patch antenna which has the advantages of being integrated by the active circuitry. A sample of patch antenna and patch array are designed and fabricated to be tested for their functionality. Printing antenna on Silicon substrate is a compact and cost-effective approach. However, antenna on Silicon will have poor gain and will also suffer from surface wave (SW) excitation. The reason for this is Silicon high dielectric constant and loss. Surface wave can be easily excited on high dielectric constant substrate which results in gain drop and distortion in radiation pattern. To avoid substrate loss, available back etching in foundry process is used to remove the silicon under the radiating antenna and improve the gain. To kill the surface wave, a type of engineered material- called Electromagnetic Band-Gap (EBG)- is designed to filter the SW around the antenna's frequency of operation. To test the fabricated antenna, a measurement setup is implemented to do refection coefficient and radiation pattern measurement. Measured S parameters show that there is frequency shift in response of measured antenna with respect to the simulated one. This shift can be attributed to uncertainty about the dielectric constant of Silicon at W-band. To find the exact value of Silicon dielectric constant, a measurement setup based on free space method is devised to determine the exact value of the silicon dielectric constant at W-Band frequency range.
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