• Journal of Broadcast Engineering
• /
• v.3 no.1
• /
• pp.93-99
• /
• 1998

본 논문에서는 Ka-밴드 위성통신 송신주파수대역(30.085∼30.885 GHz)의 대역통과 필터를 유도성 fin-line 구조를 이용하여 분석, 설계 및 제작하였다. 도파관내의 공진기들이 전계면에 수직한 금속 fin으로 구성된 구조를 해석하는데 가장 적합한 모드정합법을 사용하여 설계하였다. 제작된 필터는 마이크로파대역 뿐만 아니라 밀리미터파대역의 주파수에서도 우수한 필터특성을 갖는다는 특징을 가지고 있으며, 상업용 도파관을 사용하는 대신에 가격이 저렴하고 가공이 용이한 알루미늄을 사용함으로써 대량생산이 가능하다. 또한 도파관내 금속삽입형태에 의한 대역 통과 필터의 구현이 아닌 유한한 두께를 갖는 포토-에칭된 유전체 기판을 삽입함으로써 제작성의 어려움을 해결하였다. 설계, 제작된 필터의 측정결과 통과대역내에서 1.6dBal만의 삽입손실과 18dB이상의 반사손실을 갖는 응답특성을 얻었으며 이론에 의한 계산치와 측정치와의 비교를 통해 본 논문에서 제안된 설계방법의 타당성을 입증하였다.

• Electrical & Electronic Materials
• /
• v.7 no.5
• /
• pp.403-408
• /
• 1994

Dielectric and structural properties of $Ba_{1-x}$(Z $n_{1}$3/T $a_{2}$3/) $O_{3}$+1 mol% Mn $O_{2}$ (x=0, 0.01, 0.02, 0.03, 0.04) ceramics was investigated at microwave frequencies. With $Ba_{+2}$ shortage, the sinterability and the unloaded Q( $Q_{u}$) were much improved, and the ordering in B site and the lattice distortion was greatly enhanced and the structure approached the completely ordered structure. $Q_{u}$ was strongly correlated with these factors such as ordering ratio, lattice distortion and sinterability, and had the maximum value of 7500 at x=0.01. The dielectric constant was near 30 and the temperature coefficient of the resonant frequency was 2 ppm/.deg. C at x=0.01.1.1.1.

• Progress in Superconductivity
• /
• v.4 no.2
• /
• pp.137-143
• /
• 2003

In measuring the microwave surface resistance of high-Tc superconductor (HTS) films using the dielectric-loaded cavity resonator method, one of the most important factors that limit the measurement sensitivity is the measurement error in the loss tangent ($tan\delta$) of the dielectric rod placed inside the cavity. We have measured the effective surface resistance ( $R_{S}$ $^{eff}$) of$ YBa_2$$_Cu3$$_{7-{\delta}}$ (YBCO) films and the $tan\delta$ of rutile ($TiO_2$) using the 'two-tone'method suggested by Kobayashi et at. [IEEE, MTT-S Digest, 495, (2001)], which enables simultaneous measurements of both the $R_{S}$ $^{eff}$ fof HTS films and the $tan\delta$ of the rutile with high sensitivity. A rutile-loaded cavity resonator with the $TE_{012}$ and $TE_{021}$ resonant frequencies at 13.67 - 14.01 GHz is used for this purpose. At temperatures where the two modes do not couple with other modes, the $R_{S}$ $^{eff}$ of YBCO films and $tan\delta$ of rutile measured by the two-tone method appear to match well with the corresponding values measured using the reported $tan\delta$ values of sapphire within 10 %. Usefulness of the 'two-tone' method for microwave characterization of HTS films and dielectrics is discussed.d.ielectrics is discussed.ussed.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.4
• /
• pp.756-760
• /
• 2007

The $(1-x)Mg_4Ta_2O_9-xwt%TiO_2\;(x=5\sim20)$ microwave dielectric ceramics were prepared by solid-state reaction method and sintered at $1450^{\circ}C$. According to the X-ray diffraction data, the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics had main phase of $Mg_4Ta_2O_9$ and $MgTi_2O_5$ peaks were added by increasing of $TiO_2$ addition. Microwave dielectric properties of the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics were influenced by $MgTi_2O_5$ phase and properties of $TiO_2$. There was a little decrement of the quality factor from 116,800GHz of pure $Mg_4Ta_2O_9$ to 100,100GHz of 15wt% $TiO_2$ added one. But there was excellent improvement in temperature coefficient of the resonant frequency (TCRF) by addition of 15wt% $TiO_2$. The dielectric constant quality factor and TCRF of the $Mg_4Ta_2O_9-xwt%TiO_2$ ceramics sintered at $1450^{\circ}C$ were $13.08\sim16.41,\;45,000\sim165,410GHz,\;-24.82\sim+3.88ppm/^{\circ}C$, respectively, depending on the value of x. Simulated dielectric resonator (DR) with $Mg_4Ta_2O_9-15wt%TiO_2$ ceramics had the operating frequency of 11.97GHz and $S_{2,1}$ of -35.034dB.