Cylindrical Conformal Microstrip Yagi Array with Endfire Radiation and Vertical Polarization

Authors: Yulong Xia, Liangmengcheng Zhu, Qi Zhu

Source: FERMAT, Volume 18, Communication 11, Nov-Dec, 2016

Abstract: Yagi-Uda antenna has been a classic travelling wave antenna since it was proposed by Yagi and Uda in 1928 [1]. Because of their wide bandwidth, high directivity and easy fabrication, Yagi-Uda antennas have been widely used into many fields, such as wireless communication and space information transmission. While, in many applications, Yagi antennas are need to have low profile to meet the requirement of being conformal to the conductive surfaces. Besides, Yagi antennas in these applications are usually required to generate vertical polarized radiation to achieve low attenuation loss [2].

Although various kinds of Yagi antennas have been proposed, it’s still difficult to achieve both vertical polarization and exactly endfire radiation on a conductive surface under the condition of low profile. Classic Yagi antenna, which uses electric dipoles as the elements, has a height of λ/2. The Yagi antenna based on the monopole antennas [3] can provide a vertical polarized radiation, but it still has a high profile of λ/4. Yagi antenna based on the microstrip antennas (MSAs) [4] has low profile and vertical polarized radiation, but it hard to realize exactly endfire radiation. Yagi antenna with the printed dipoles as it elements [5] has low profile and exactly endfire radiation, but it just generated a horizontal polarized radiation. Yagi antenna based on microstrip magnetic dipoles was proposed in [6], the low profile antenna can provide good endfire radiation with vertical polarization, however, the antenna has a large width, especially high SLL when the length of the antenna increased.

A cylindrical conformal microstrip Yagi antenna working around 10 GHz with endfire radiation and vertical polarization is proposed. The presented Yagi antenna has advantages of low profile, small size and high endfire gain. Each element of the Yagi antenna is a MSA with one edge shorted, which can be regarded as a half MSA (HMSA). Furthermore, a cylindrical conformal Yagi array consisted of 24 above Yagi antennas is presented to improve the endfire radiation performance. Simulated results show that an exactly endfire radiation with 21 dB gain can be provided. Besides, beaming scanning in the endfire direction with side lobe level (SLL) lower than -20 dB can also be realized by adjusting the amplitudes and phases of the antennas in the array.

Index Terms: Cylindrical conformal, Yagi antenna array, endfire radiation, vertical polarization

View PDF

Cylindrical Conformal Microstrip Yagi Array with Endfire Radiation and Vertical Polarization