| 摘要 |
PURPOSE:To enable a band-pass filter to operate adequately when it is used by being coupled with an amplifier or oscillator by allowing a fundamental wave fo pass through with no attenuation and by absorbing and attenuating a double wave inside without causing its reflection. CONSTITUTION:To constitue this BPF, the transmission line with impedance ZO is cut into transmission lines 11 and 12, where another transmission line of lambdag/2 in length (g is the wavelength of a fundamental wave) with impedance Z'O (Q'O>ZO) is inserted in series, and stubs 16 and 17 of lambdag/8 in lenght are provided at points lambdag/8 away from the center point of the inserted transmission line; and then, resistances 20 and 21 with the same value as ZO are connected to connection points C and D respectively, and to their other-side terminals, parallel element 18 and 19 made of a transmission line of lambdag/4 in length wigh any impedance value are connected respectively (the other terminal of each one is grounded). On the characteristic curve of the BPF, an attenuation pole appears at the double frequency of fundamental wave (fO), i.e. approximate 11GHz and since the VSER is small over the entire area, the refelction of a signal is small not only in the pass band but also the stopping band. |
