雙極化對數週期天線與超寬頻平衡器在印刷電路板上之整合設計

Abstract

對數週期偶極天線具有線性極化與平穩的增益場型之寬頻特性，適合應用在EMI或天線的量測上。傳統的對數週期偶極天線通常是由金屬圓柱所組成，其天線的體積和重量較大，且製作上誤差難控制。在本論文中，吾人利用印刷電路板技術，設計出平面式雙極化對數週期天線,並整合超寬頻平衡器（Balun）饋入。本論文前半部成功運用雙層印刷電路板設計出單極化平衡器與對數週期天線，操作頻寬為1.0GHz~6.0GHz。論文後半部，成功設計出操作頻帶為1.0GHz 6.0GHz之雙極化平衡器，並將之整合至雙極化對數週期天線，整合後之雙極化天線在全頻段之正向增益表現非常平穩，介於0dBi至6dBi之間，交叉極化隔離度則約為15dB。

The log-periodic dipole antenna (LPDA) has broadband properties in the antenna impedance, radiation patterns, and the linear polarization very suitable for the source antenna in the EMI/Antenna measurement. Traditional LPDA is made of metal cylinders fed by coaxial cables making the antenna heavy and difficult to fabricate. In this thesis, we proposed a dual-polarized log periodic antenna(LPA) integrated with a embedded ultra wideband (UWB) balun. In the first half of the thesis, we designed a single-polarized Marchand balun integrated with LPA in multi-layered PCB, achieving a wide bandwidth covering 1.0GHz~6.0GHz. In the second half of this thesis, we proposed a dual-polarized LPA with UWB balun. Stable gain patterns were achieved with antenna gain range from 0dB to 6dB with polarization isolation better than 15 dB.