基於互補裂隙環形共振腔於小尺寸微帶分頻器設計

Abstract

本論文主要以互補式裂隙環型共振器為電路之基礎，提出兩種不同操作頻率的帶通濾波器縮小化的設計。此兩種帶通濾波器分別操作於2.45 GHz以及1.85 GHz。互補式裂隙環型共振器是一種後設材料，由於它有獨特的電磁特性，所以近年來有許多文獻都將此共振腔應用於天線設計以及微波電路的縮小化方面。 論文前半部利用互補式裂隙環型共振器(complementary split ring resonators, CSRRs)並且配合微帶線耦合指叉電容實現帶通濾波器所需的電路元件。接著利用開路殘段去改善此帶通濾波器在高頻通帶選擇度不好的現象，並且提出等效電路的觀點解釋此帶通濾波器每個部分對於頻率響應曲線的影響。 論文後半部利用前半部所提出的帶通濾波器設計進行小尺寸微帶分頻器設計。經由模擬與量測結果可以得知，此分頻器有良好的特性響應，如傳輸耗損為1.1 dB以及1.43dB、訊號抑制能力分別為29.6dB以及41.21 dB，且3 dB比例頻寬為12.85%以及8.91%。除此之外，此微帶分頻器僅占用面積約51 mm×29 mm大約是(0.42λ_g×0.2λ_g)。

In this thesis, we proposed miniaturization bandpass filters (BPFs) design based on complementary split ring resonators (CSRRs) with two different operating frequency. The two BPFs are operated at 2.45 GHz and 1.85 GHz, respectively. The complementary split ring resonator, which is one kind of the meta-material, since it has unique electromagnetic characteristics, therefore there are many academic literatures about CSRRs which are applied on miniaturization of antennas and microwave circuits. In the first part of this thesis, a BPF is implemented by utilizing CSRRs and microstrip line coupled interdigital-capacitors to realize necessary circuit components. The open stubs are used to improve the selectivity of the higher edge of the passband, and we proposed the equivalent circuit to explain the frequency responses which are affected by the parts of the BPF. In the last part of this thesis, we use the proposed BPF to design the compact size microstrip diplexer. By simulation and measurement results, the diplexer has good characteristic responses, such as transmission loss (1.1 dB and 1.4 dB),signal suppression (29.6 dB and 41.21 dB),and 3 dB fractional bandwidth (12.85% and 8.91%). Moreover, the diplexer occupy a small area and has the dimensions of 51 mm×29 mm about 0.42λg × 0.2λg.