I. INTRODUCTION

II. LINEARLY POLARIZED BEAM SCANNING ANTENNA

III. CIRCULARLY POLARIZED BEAM SCANNING ANTENNA

IV. CONCLUSION

REFERENCES

In this paper, novel compact high gain broadband leaky-wave antenna (LWA) using TE220 high-order mode is proposed. The high-order mode antenna not only possesses more compact structure with higher gain, but also simplifies the feeding network of the antenna array and relaxes processing tolerance. The radiation element consists of an SIW cavity etched with 2 × ۲ slot array on the top surface, which is excited by a microstrip-slot coupling structure. Microstrip spoof surface plasmon polariton (SPP) is worked as a slow-wave transmission line (TL) to increase the beam scanning range of a four elements periodic array antenna. The antenna was simulated, optimized and fabricated, which verified theoretical analysis. Experimental results show that the linearly polarized (LP) beam scanning antenna has a bandwidth of 53.5% (from 12.6 GHz to 21.8 GHz) with beam scanning range from −۲۴◦ to +32◦ and gain in the range of 10.2 dBi to 12.4 dBi. Then a linear-to-circular polarization converter is loaded to implement a circular polarization (CP) beam scanning antenna. The proposed antenna has the features of compact size, low profile, high gain, large beam scanning range and flexible polarization conversion.

INTRODUCTION

With the rapid development of satellite communication and wireless communication, beam scanning antenna with compact size, low profile, high gain and wide scanning range has been widely used [1]. As a basic type of beam steering antenna, leaky-wave antenna (LWA) has attracted more attention because of its low profile, compact size, low cost and easy integration with planar circuits [2]–[۶]. However, the LWA has an inherent disadvantage that radiation efficiency is not high, resulting in low gain. Traditional methods of increasing gain include increasing element number or loading lenses. However, it results in the increase of antenna size and profile thickness, which is not desirable [1], [7]. Wide scanning range is required for beam scanning antennas. For traditional right-handed (RH) LWAs, they only have an ability of forward scanning with limited scanning range. Then composite right/left-handed (CRLH) transmission line (TL) was investigated to realize beam steering from backward directions to forward directions [8]–[۱۰].Furthermore, a bending structure can also be used to enhance the phase shift and increase the beam scanning range by increasing the length of TLs between adjacent radiating elements [7], [11]. In addition, another way to increase the beam scanning range is to use slow-wave TLs feeding structure [12]–[۱۵]. The TL structure with slow-wave dispersion characteristics can produce larger phase difference between adjacent radiation elements within the same frequency band, thus enlarging the beam scanning range.