A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two mo...A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.展开更多
This paper describes in detail an acoustical array structure with four elements that have cosine directivity function over a certain frequency range. The acoustical axis directions of these elements are orthogonal to ...This paper describes in detail an acoustical array structure with four elements that have cosine directivity function over a certain frequency range. The acoustical axis directions of these elements are orthogonal to each other, so their beams cover all bearing angles within 360° . By use of the amplitude bearing method, it is easy to detect the bearing of incident acoustic signal. A special sound reflection foam rubber is designed as a back baffle of the array. It has been shown, in practice, that the constant beam-width has been obtained for a multiple frequency band of the ratio of 8:1. The paper also gives a mathematical model for the array structure. The theoretical values are consistent with the measured results.展开更多
基金supported by the NSFC-Guangdong (Grant No.U1035002) and NSFC-NSAF (Grant No.10976010)National Key Project of Science and Technology of China (Grant No. 2009ZX03006-003)the Technology Key Projects of Guangdong Province of China (Grant Nos.2009A080207006 and 2009A080207002)
文摘A compact and broadband circularly polarized （CP） annular ring antenna with wide beam-width is proposed for multiple global navigation satellite systems （GNSS） in the L1 band. The annular ring is excited by two modified L-probes with quadrature phase difference. It has a 36.3% 10-dB return loss bandwidth and a 13% 3-dB axial ratio bandwidth, because of the orthogonal L-probes with 90° phase difference. The measured peak gain of the antenna is 3.9 dBic. It can detect the satellites at lower elevation as its half power beam-width （HPBW） is 113° in both the x-z and y-z planes, achieving a cross-polarization level of larger than 25 dB. Noticeably, the antenna achieves 89% size reduction compared with the conventional half wavelength patch antennas. It can be used in hand-held navigation devices of multiple GNSS such as COMPASS, Galileo, GPS and GLONASS.
文摘This paper describes in detail an acoustical array structure with four elements that have cosine directivity function over a certain frequency range. The acoustical axis directions of these elements are orthogonal to each other, so their beams cover all bearing angles within 360° . By use of the amplitude bearing method, it is easy to detect the bearing of incident acoustic signal. A special sound reflection foam rubber is designed as a back baffle of the array. It has been shown, in practice, that the constant beam-width has been obtained for a multiple frequency band of the ratio of 8:1. The paper also gives a mathematical model for the array structure. The theoretical values are consistent with the measured results.
