Abstract: An electronic impedance tuner comprises an adjusting circuit, N cell tuning circuits identical in structure and a switch controller. The adjusting circuit comprises a first microstrip line, a second microstrip line, a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor and a first PIN diode. Each cell tuning circuit comprises a third microstrip line, a fourth microstrip line, a fourth capacitor, a fifth capacitor, a second PIN diode and a third capacitor. The capacitance Cd of the fourth capacitor meets the condition: 4 ? ? Y s N ? ? ? ? ? f 2 ? ? ? req ? 1 - ? ? req ? 2 ? C d ? Y s ? ? ? f 1 ? ? ? req ? 1 - ? ? req ? 2 . The length d of the third microstrip line meets the condition: ? 1 / 4 ? ( N + 1 ) < d < c 4 ? ? reff ? [ ( C d · Z 0 ) 2 + ( 2 ? ? ? f Bragg ) 2 - C d · Z 0 ] .

Abstract: An electronic impedance tuner comprises an adjusting circuit, N cell tuning circuits identical in structure and a switch controller. The adjusting circuit comprises a first microstrip line, a second microstrip line, a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor and a first PIN diode. Each cell tuning circuit comprises a third microstrip line, a fourth microstrip line, a fourth capacitor, a fifth capacitor, a second PIN diode and a third capacitor. The capacitance Cd of the fourth capacitor meets the condition: 4 ? ? Y s N ? ? ? ? ? f 2 ? ? ? req ? 1 - ? ? req ? 2 ? C d ? Y s ? ? ? f 1 ? ? ? req ? 1 - ? ? req ? 2 . The length d of the third microstrip line meets the condition: ? 1 / 4 ? ( N + 1 ) < d < c 4 ? ? reff ? [ ( C d · Z 0 ) 2 + ( 2 ? ? ? f Bragg ) 2 - C d · Z 0 ] .