Pin diode attenuators

Claim 2

A microwave variable attenuator including an input and an output terminal, said input and output terminals being connected to external circuits presenting a first characteristic impedance, said microwave variable attenuator comprising: a plurality of line sections, coupled between said input and output terminals, each presenting a second characteristic impedance different from said first characteristic impedance; and variable attenuation means connected to said line sections.

Claim 3

A variable attenuator according to claim 1, wherein: line said variable attenuation means are connected between said sections and a radio-frequency ground; and said second characteristic impedance is greater than said first characteristic impedance.

Claim 4

A variable attenuator according to claim 1, wherein: said variable attenuation means are serially connected with said line sections; and said second characteristic impedance is smaller than said first characteristic impedance.

Claim 5

A variable attenuator according to claim 1, wherein said line sections have a length of substantially 1/4 of the wavelength of the signal attenuated by the variable attenuator.

Claim 6

A variable attenuator according to claim 1, further comprising a DC separator means.

Claim 7

A variable attenuator according to claim 1, further comprising: a separator having a first terminal coupled to said input terminal, a second terminal coupled to said line sections by means of a transmission line having said first characteristic impedance, and a third terminal coupled to a matched load, for dissipating power reflected from said variable attenuator.

Claim 8

A variable attenuator according to claim 6, wherein said separator is implemented by a circulator.

Claim 9

A variable attenuator according to claim 1, further comprising a power divider having a first terminal coupled to said input terminal, a second and a third terminal coupled to said line sections by means of transmission lines having said first characteristic impedance, and a fourth terminal coupled to a matched load, for dissipating power reflected from said variable attenuator.

Claim 10

A variable attenuator according to claim 8, wherein said power divider is a 90° and a 3 DB divider.

Claim 11

A variable attenuator according to claim 5, wherein: said DC separator means is a capacitor.

Claim 12

A variable attenuator according to claim 5, wherein said DC separator means is a faced line section.

Claim 13

A variable attenuator according to claim 9, wherein said 90° and 3 DB power divider is implemented by a line section coupled at radio frequency and decoupled at direct current.

Claim 14

A variable attenuator according to claim 6 or 8, wherein said matched load is concentrated resistor.

Claim 15

A variable attenuator according to claim 6 or 8, wherein said matched load is distributed resistor.

Claim 16

A variable attenuator according to claim 2, wherein: said variable attenuation is a pin diode; and said radio-frequency ground is obtained by means of a first quarter-wavelength transmission line presenting a third characteristic impedance smaller than said first characteristic impedance.

Claim 17

A variable attenuator according to claim 3 further comprising: a first open transmission line, coupled to said line sections, including a first quarter-wavelength component section, presenting a fourth characteristic impedance smaller than said first characteristic impedance, and a second quarter-wavelength component section presenting a fifth characteristic impedance greater than said first characteristic impedance; and a second quarter-wavelength transmission line, coupled between said line sections and ground, presenting said fifth characteristic impedance; wherein: said variable attenuation means is a pin diode.