# Hom Antenna on Chip Operating at 180 GHz Using the SiGe CMOS Process
## 1 Introduction  
In the 5G era, the operating frequency is in the millimeter wave band. Because waves are generally short, antennas are mainly targeted at applications such as short-distance communications, 5G communications, wireless communications [1; 2; 3] and imaging radar [2; 4; 5]. Antennas are widely used in various communication systems, closely integrating people and things throughout the world, forming an interconnected world [4; 6]. However, the structure of such a widely used antenna is not too complicated, which has led many people to invest in this research and develop various antennas [7]. Among them, antennas designed on wafers are popular because they are smaller in size, less susceptible to noise interference, and have excellent efficiency [8].  
CMOS (Complementary Metal-Oxide-Semiconductor) technology plays a key role in chip antenna applications in modern communications [1; 9] and radar systems [4; 5; 10]. One of its main advantages is its high degree of integration. The CMOS process allows the integration of multiple antenna elements and signal processing functions on a small chip. This highly integrated design not only saves space but also reduces the cost of the system [11].  
In addition, CMOS chip antennas have excellent power consumption performance and do not require additional manufacturing processes to integrate the antenna [12], making them suitable for use in portable and low-power devices. These advantages make CMOS a promising choice in wireless communications, radar, and other antenna applications [11].  
In the millimeter-Wave frequency band where atmospheric propagation and resistive losses are large [13; 14], high-gain antenna types can be used to solve this phenomenon [5; 7]. Horn antennas in wireless communication systems and radar systems [1; 4] are widely used because of their large gain [5; 13; 15] and high efficiency [16]. Horn antennas are characterized by their simple structure [13], easy control [5; 17], high efficiency, stableradiation direction [15, 18], moderate bandwidth [13, 15, 17, 18, 19], and powerful power processing capabilities [13], is widely used in the energy supply of tracking satellite, systems of phased array, devices of microwave heating, and as general standard components for calibrating and measuring high-gain antennas [17]. It is usually made up of metal and dielectric materials and performs consistently in various environments without requiring regular maintenance [5]. In general, the horn antenna is known for its wide-band performance [15, 17], excellent directivity [15], simple structure [17] and wide application fields. It is used in radar [5], communications [17, 20]. It plays an important role in many fields such as remote sensing and scientific research, providing reliable antenna solutions for many key applications.  
In this article, the SiGe CMOS process is used and the Horn antenna is designed on the wafer. Through the horn antenna and the theory of electromagnetism and electromagnetic waves, the horn antenna is designed on CMOS M4-M6. At the same time, this experiment is expected to operate this chip horn antenna in a frequency band with a central frequency close to 180 GHz. In the feed part, the GSG feed method is used. This feed method not only increases signal integrity and improves high-frequency performance, but is also more convenient in connection. The composition of this article introduces the results and conclusions of the antenna design, simulation, and measurement in order. All simulation results are generated using electromagnetic simulation software.