Earticle

In this paper, a size-reduced Wilkinson balun with wide harmonic-suppressed band is presented. An accurate analysis of the parallel coupled line with an open stub (PCL-OS) is carried out. The PCL-OS structure shows excellent low pass filter and harmonic-suppression characteristics, which is useful for designing a low pass filter unit cell (LUC) with a reduced size. The designed Wilkinson balun at a 2.45 GHz center frequency not only shows an excellent harmonic suppression including the 5th harmonics up to 14 GHz over 15 dB, but it also has an area reduced to 48% of the conventional one.

This paper presents a novel simple filter design method based on a parallel short-ended coupled-line structure with capacitive loading for size reduction and ultra-broad rejection of spurious passbands. In addition, the introduction of a cross-coupling capacitor into the miniaturized coupled-line can create a transmission zero at the second harmonic frequency for better frequency selectivity and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. The influence of using the connecting transmission line to cascade two identical one-stage filters is studied for the first time. Specifically, such a two-stage bandpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with low-temperature co-fired ceramic technology for application in base stations that need high power handling capability. It achieved attenuation in excess of -40 dB up to $4f_0$ and low insertion loss of -1.2 dB with the size of 10 mm ${\times}$ 7 mm ${\times}$ 2.2 mm. The measured and simulated results showed good agreement.

본 논문에서는 5.8Ghz ISM대역 평행 결합선로 대역통과 여파기를 설계 제작하였다. 긴본적인 설계는 저역통과 여파기에서 대역통과 여파기로 변환한 후, 직 병렬 공진기를 이용한 설계와 J-인버터를 이용해 평행 결합선로 대역통과 여파기를 구현하였다. 2개의 공진 주파수를 실제로 구현하기 어렵기 때문에 하나의 공진기만을 사용하기 위해 인버터를 사용하였다. 또한 실제적인 마이크로스트립 라인의 layout크기를 결정하기 위해 우수 기수 모드 임피던스를 해석하고 근사식을 통해 스트립라인의 치수를 결정하였다. 이런 과정을 토대로 5.8GHz ISM밴드용 평행 결합선로 대역통과 여파기를 설계, 제작하였다.

New measurement method of coupled transmission line characteristics is described. This method presents precision calculated values of even- and odd-mode impedances and effective dielectric constants of mictostrip parallel coupled lines from the scalar quantities obtained by transmission coefficients at two different resonance frequencies. Measured impedances and effective dielctric constants are good agreement with predicted values.

In this paper, a lumped equivalent circuit for a conventional parallel directional coupler is proposed. The equivalent circuit and design formula for the presented lumped element coupler is derived based on the even- and odd-mode properties of a parallel-coupled line. By using the derived design formula, we have designed the 3dB and 4.7dB lumped element directional couplers at the center frequency of 3.4GHz and 5.6GHz. A chip type directional coupler has been designed to fabricate with MMIC(Monolitic Microwave integrated circuit) process. Excellent agreements between simulations and measurements on the designed directional couplers show the validity of this paper.

In this paper, we have designed a small size lumped/distributed hybrid element directional coupler using parallel coupled-line theory. a hybrid lumped equivalent circuit for a conventional parallel directional coupler is proposed. The equivalent circuit and design formula for the presented lumped element coupler are derived based on the even- and odd-mode properties of a parallel-coupled line. By using the derived design formula, we have extracted design parameters and designed the 3㏈ and 10㏈ small size lumped element directional couplers at the center frequency of 2Ghz. Excellent agreements between design theory and simulation on the designed directional couplers show the validity of this paper.

In this paper, a novel lumped equivalent circuit for a conventional parallel directional coupler is proposed. The equivalent circuit and design formula for the presented lumped element coupler is derived based on the even-and odd-mode properties of a parallel-coupled line. By using the derived design formula, we have designed the 3㏈ and 10㏈ lumped element directional couplers at the center frequency of 100Mhz. Furthermore, a chip type directional coupler has been designed to fabricate with multilayer configurations by employing the Low Temperature CofiredCeramic (LTCC) process. Designed chip-type directional coupler has a 10㏈-coupling value at the center frequency of 2㎓. Excellent agreements between simulations and measurements on the designed directional couplers show the validity of this paper