| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a high frequency variable filter for maintaining pass bandwidth almost constant when a frequency varies. Ž<P>SOLUTION: The high frequency variable filter is provided with varactors 2a to 2c whose one ends are grounded, meander line inductors 4a to 4c having a fixed value, transmission lines 5a to 5c having a fixed length, transmission lines 6a and 6b having almost the same length as the transmission lines 5a to 5c, and an input-output terminal 8. The fixed length of the transmission lines 5a to 5c is set to be almost 1/4 wavelength in the center frequency in the variable frequency range of a pass frequency. The varactors 2a to 2c, the inductors 4a to 4c, and the transmission lines 5a to 5c are connected in series to constitute a single unit of variable resonance circuit. The transmission lines 6a and 6b connect plural units of variable resonance circuits in parallel to input and output a high frequency signal from/to each variable resonance circuit from the input-output terminal 8. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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