| 摘要 |
PROBLEM TO BE SOLVED: To change the attenuation of a high frequency signal without changing its characteristic impedance by providing a variable resistor between ground and a high potential terminal of a connection part between two hybrid transformers connected in cascade and varying the resistance. SOLUTION: A high frequency signal is divided into two by a hybrid transformer 11 and synthesized by a hybrid transformer 12. When the resistance of a variable resistor 13 is infinite, the attenuation of the variable resistor 13 is the same as the loss of the hybrid transformers 11, 12. When the value of the variable resistor 13 is AΩ, mismatching is caused by the resistance AΩ, a mismatching loss is produced and the attenuation loss is consumed in a resistor of an isolation port built in the hybrid transformers 11, 12. Thus, the lossαis added to the loss of the hybrid transformers 11, 12. Although mis-matching loss is produced by varying the variable resistor 13, the input/output impedance of the hybrid transformers 11, 12 is compensated and the characteristic is made constant regardless of a change in the attenuation.
|
