Advanced waveguide antennas for automotive radar

The demand for safety in automobiles in recent years has increased in a significant way. One of the most important safety features is that of radar systems, which detect obstacles and other vehicles in proximity. Radar antennas can be classified into two main categories: printed radar antennas and 3D waveguide antennas. Both these types of antennas have their own unique characteristics and are used in different applications. Printed antennas, also known as planar antennas, are typically flat and have a simple, two-dimensional structure. They are often used in radar systems because they are relatively inexpensive and easy to manufacture. 3D antennas, on the other hand, have a more complex, three-dimensional structure and can have a variety of shapes. They are often used in advanced radar systems because they can provide higher efficiency than printed antennas. In recent years, there have been new regulations in the automotive industry for the use of 77GHz radar systems, as opposed to the previously commonly used 24GHz systems. This shift is driven by several factors, including the reduced dimensions and the increased resolution of 77GHz systems, as well as the ability to detect small and fast-moving objects. However, this shift to 77GHz radar systems comes also with challenges. One of the main challenges is the increased complexity of the antenna systems, which can make them more difficult to manufacture and more expensive to produce. The objective of this thesis work is to look into the design and development a 3D slotted waveguide antenna for automotive radar application working at around 77-81 GHz. The antenna is based on the WR10 of reduced height rectangular waveguide with longitudinal slots cut on top of it, which provide the apertures through which the EM energy can be radiated. Different types of feedings for the antenna are presented, including a microstrip and a waveguide feeding, in which an L-transition between a WR12 and WR10 with reduced height is also designed. Ultimately, an array of antennas is designed taking in consideration the L-transition, the dimensions of the single antennas and the characteristics of arrays for radar application. The proposed designs are done using CST Microwave Studio simulation tool, which is a reliable and widely used EM design software. The results yielded from the software, among other parameters, include the s-parameters, radiation efficiencies, and the radiation pattern. An optimization process followed the designs, which involved an extensive adjustment of various dimensions and structures of the antenna, together with continuous simulations of these adjustments. Based on the simulation results, the design is tweaked to fit automotive radar requirements and usage.