With the developments in science and technology, the number of car ownerships is rapidly increasing. As a result of vehicular mobility, efficiency is worsening. In addition, due to the severe traffic environment, traffic safety is being threatened. The ITS (intelligent transportation system) and ACC...
With the developments in science and technology, the number of car ownerships is rapidly increasing. As a result of vehicular mobility, efficiency is worsening. In addition, due to the severe traffic environment, traffic safety is being threatened. The ITS (intelligent transportation system) and ACC (adaptive cruise control) system are being considered in order to overcome this traffic safety threat due to the testing traffic environment. Car radar technology has been used as the core technology of these systems. Millimeter-wave radar is being intensively studied in car radar systems because the millimeter-wave has low loss in all weather conditions and is easy to use. ITU-R M1452-2 provides a recommendation for millimeter-wave automotive radar operating in the 76~77 GHz range, which can be used in an ACC system and collision avoidance system. For several decades, microstrip patch antenna has been widely studied in antenna RF systems with microwaves or millimeter-waves because of its small size, low weight and ease of fabrication. However, at the millimeter-wave frequency, conductor loss of microstrip patch antennas becomes severe and the radiation efficiency of the antenna is reduced significantly. In order to overcome this problem at millimeter-wave frequencies, DRA (dielectric resonator antenna) is considered as an alternate. DRA has advantages at millimeter-wave frequencies because the only loss of DRA is the loss due to imperfect dielectric material, which can be minimized in practice. In addition to its zero conductor loss, DRA also has the advantages of a wider impedance bandwidth, higher radiation efficiency, no distortion from surface waves, simple configuration, and various radiation patterns along the feeding modes. Therefore, DRA is suitable because the microstrip antenna radiates only through two narrow radiation slots, whereas the DRA radiates through the whole surface except for the grounded part. In this paper, in order to get high-gain performance for a 76~77-GHz anti-collision car radar system, 16x16 millimeter-wave DRA arrays are designed and their performance is evaluated. The dielectric manufactured by the LTCC (Low Temperature Co-fired Ceramic) process is used for the DRA element because of LTCC's characteristics of low loss and high temperature stability. Antenna feeding is designed using a microstrip transmission line, which is lighter weight, has a small volume and is easy to manufacture. First, a single DRA element is designed to provide the desired frequency band, gain, and radiation pattern. Single DRAs are designed with aperture-coupled feeding, microstrip feeding and probe feeding. Based on the single DRA element, a 2x2 array is designed and optimized. 2x2 arrays are designed with microstrip feeding and probe feeding because for single antenna cases, the gain of a microstrip feeding DRA and probe feeding DRA are even higher than that of an aperture-coupled feeding DRA. A 16x16 array is designed using the 2x2 array as an element radiator. 8x8 arrays of the 2x2 DRA array make 16x16 DRA arrays. The feed lines of the 8x8 arrays are designed for different current distribution schemes - uniform current distribution, triangular current distribution, and Dolph-Chebyshev current distribution. The feed line design uses a quarter-wavelength transformer. The radiation pattern and gain is calculated using the principle of multiplication. The antenna performances of all designed antennas are calculated and compared with each other. The maximum gain of the designed antenna is 31.1 dBi. The designed 16x16 array can be used in an anti-collision car radar system.
With the developments in science and technology, the number of car ownerships is rapidly increasing. As a result of vehicular mobility, efficiency is worsening. In addition, due to the severe traffic environment, traffic safety is being threatened. The ITS (intelligent transportation system) and ACC (adaptive cruise control) system are being considered in order to overcome this traffic safety threat due to the testing traffic environment. Car radar technology has been used as the core technology of these systems. Millimeter-wave radar is being intensively studied in car radar systems because the millimeter-wave has low loss in all weather conditions and is easy to use. ITU-R M1452-2 provides a recommendation for millimeter-wave automotive radar operating in the 76~77 GHz range, which can be used in an ACC system and collision avoidance system. For several decades, microstrip patch antenna has been widely studied in antenna RF systems with microwaves or millimeter-waves because of its small size, low weight and ease of fabrication. However, at the millimeter-wave frequency, conductor loss of microstrip patch antennas becomes severe and the radiation efficiency of the antenna is reduced significantly. In order to overcome this problem at millimeter-wave frequencies, DRA (dielectric resonator antenna) is considered as an alternate. DRA has advantages at millimeter-wave frequencies because the only loss of DRA is the loss due to imperfect dielectric material, which can be minimized in practice. In addition to its zero conductor loss, DRA also has the advantages of a wider impedance bandwidth, higher radiation efficiency, no distortion from surface waves, simple configuration, and various radiation patterns along the feeding modes. Therefore, DRA is suitable because the microstrip antenna radiates only through two narrow radiation slots, whereas the DRA radiates through the whole surface except for the grounded part. In this paper, in order to get high-gain performance for a 76~77-GHz anti-collision car radar system, 16x16 millimeter-wave DRA arrays are designed and their performance is evaluated. The dielectric manufactured by the LTCC (Low Temperature Co-fired Ceramic) process is used for the DRA element because of LTCC's characteristics of low loss and high temperature stability. Antenna feeding is designed using a microstrip transmission line, which is lighter weight, has a small volume and is easy to manufacture. First, a single DRA element is designed to provide the desired frequency band, gain, and radiation pattern. Single DRAs are designed with aperture-coupled feeding, microstrip feeding and probe feeding. Based on the single DRA element, a 2x2 array is designed and optimized. 2x2 arrays are designed with microstrip feeding and probe feeding because for single antenna cases, the gain of a microstrip feeding DRA and probe feeding DRA are even higher than that of an aperture-coupled feeding DRA. A 16x16 array is designed using the 2x2 array as an element radiator. 8x8 arrays of the 2x2 DRA array make 16x16 DRA arrays. The feed lines of the 8x8 arrays are designed for different current distribution schemes - uniform current distribution, triangular current distribution, and Dolph-Chebyshev current distribution. The feed line design uses a quarter-wavelength transformer. The radiation pattern and gain is calculated using the principle of multiplication. The antenna performances of all designed antennas are calculated and compared with each other. The maximum gain of the designed antenna is 31.1 dBi. The designed 16x16 array can be used in an anti-collision car radar system.
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#유전체 공진기 안테나 LTCC 차량용 레이더 밀리미터파
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