可抑制諧波之開槽耦合開槽偶極及迴圈天線

Abstract

本論文主要是在探討開槽偶極天線與開槽迴圈天線的諧波抑制。本論文使用了一個新技術去抑制開槽偶極天線與開槽迴圈天線的諧波輻射，也就是使用了”耦合技術”在開槽偶極天線與開槽迴圈天線上。 首先，本論文介紹了四分之一波長阻抗轉換器與耦合技術。四分之一波長阻抗轉換器用來轉換終端狀態。而從耦合技術來看，一段耦合線可以被當作成一個濾波器去抑制特定的頻率。 本論文提出了使用共面波導饋入且附帶四分之一波長阻抗轉換器之開槽偶極與迴圈天線，此開槽偶極與迴圈天線的功能主要是去抑制諧波輻射。由於此開槽偶極與迴圈天線主要是根據傳統開槽偶極與迴圈天線變化而成，此附帶有四分之一波長阻抗轉換器之開槽偶極與迴圈天線相當的簡單且容易設計。此共面波導饋入之開槽偶極與迴圈天線皆擁有一對耦合線段，並且巧妙的使用了耦合技術去降低諧波輻射。四分之一波長阻抗轉換器使得耦合線段的其中之一輸入阜由短路轉換為開路，因此這個帶有一個開路與一個短路的耦合線段就像是一個帶拒型濾波器。只要設計這個帶拒型濾波器的工作頻率為二倍頻的諧波頻率，那麼此開槽偶極與迴圈天線就可以抑制二倍頻的諧波共振。 另外，本論文又提出一個使用共面波導饋入電感式耦合開槽迴圈天線，此開槽迴圈天線的功能亦是去抑制諧波輻射。因為短路在開槽天線上是一個直覺式的設計，此共面波導饋入電感式耦合開槽迴圈天線直接利用耦合線段上的短路去做設計。既然帶有一個開路與一個短路的耦合線段就像是一個帶拒型的濾波器，帶有兩個短路的耦合線段一樣也可以是一個帶拒型的濾波器。只要設計好耦合線段的長度，此耦合線段在此特定長度下可以相對應一個拒斥的頻率。只要將此特定的拒斥頻率設計在高倍頻的共振頻率上，此共面波導饋入電感式耦合開槽迴圈天線即可抑制高倍頻的諧波共振。 因為此開槽迴圈天線擁有一對耦合線段，每個耦合線段可以設計成擁有各自不同的電氣長度。各自擁有不同電氣長度的耦合線段可以抑制各自對應的特定頻率。較長電氣長度的耦合線段是用來抑制較低倍數的諧波頻率，而較短電氣長度的耦合線段是用來抑制較高倍數的諧波頻率。只要耦合線段各自對應的特定頻率是同時且各自地設計在不同倍數的諧波頻率，此共面波導饋入電感式非均衡耦合開槽迴圈天線可以同時抑制兩個高倍頻的諧波共振。

This dissertation focuses on the development of slot dipole and slot loop antennas for harmonic suppression. As a new technique to suppress the harmonic radiation from the slot dipole and slot loop antennas, the coupling slots are introduced to the slot dipole and slot loop antennas. In the beginning, the quarter-wave impedance and coupling technique are introduced. The quarter-wave impedance is used to transform terminations. From the coupling technique, a coupled line is used as a filter to suppress specific frequency. CPW-fed slot dipole and loop antennas with quarter-wave impedance transformer are developed for harmonic suppression. Basing on the conventional slot dipole and loop antennas, the proposed CPW-fed slot dipole and loop antennas with quarter-wave impedance transformer are simple and easy to design. Both of the CPW-fed slot dipole and loop antennas possess a pair of coupled line section, and utilize the coupling technique to reduce the harmonic resonance. The quarter-wave impedance transformer lets a short circuit transform to an open circuit for one port of the coupled line section, and the coupled line section with a short and an open circuit works as a bandstop filter at a specific frequency. As long as designing the specific frequency at the 2nd harmonic frequency, the 2nd harmonic resonance of the slot dipole and loop antennas can be suppressed. Next, a CPW-fed inductively coupled slot loop antenna for harmonic suppression is proposed. Because short circuit is an intuition solution for slot type antenna, the CPW-fed inductively coupled slot loop antenna utilizes the original short circuit to terminate a pair of coupled line section. Since the coupled line section with a short and an open circuits can works as a bandstop filter, it can also work as a bandstop filter with two short circuits for a specific electrical length at a specific frequency. As long as the specific frequency is designed at the higher order frequencies, that higher order harmonic resonance of the CPW-fed inductively coupled slot loop antenna can be suppressed. Since the CPW-fed inductively coupled slot loop antenna possesses a pair of coupled line section, each one of the pair of the coupled line section can possess different electrical length. Different electrical length of the pair of coupled line section can suppress different specific frequencies. The longer electrical length of the pair of coupled line section is utilized to suppress the lower harmonic frequency, and the shorter electrical length of the pair of coupled line section is utilized to suppress the higher harmonic frequency. As long as two different specific frequencies are designed at the higher order frequencies simultaneously, two higher order harmonic resonances of the CPW-fed inductively coupled unbalanced slot loop antenna can be suppressed simultaneously.