Abstract: A realization method of a multiple passband filter that equalizes a group delay without using an external equalizer is disclosed. The realization method includes the steps of: a) calculating a transfer function based on poles and zeros; b) extracting an input/output coupling coefficient and a coupling matrix from the calculated transfer function as a network parameter; and c) physically designing and realizing elements of the filter to have the extracted network parameter.

Abstract: The present invention relates to a microwave variable attenuator variably attenuating while maintaining a matching state. The microwave variable attenuator includes: an input terminal for inputting a microwave signal; an output terminal for outputting a microwave signal; a control voltage supplying unit for supplying a control voltage; an input terminal matching unit for matching an impedance of the input terminal in response to the control voltage; an output terminal matching unit for matching an impedance of the output terminal in response to the control voltage; and an attenuating unit for attenuating the microwave signal inputted to the input terminal based on an attenuation controlled according to the control voltage and outputting the attenuated microwave signal, wherein the attenuating unit includes a pin diode and a resonant inductor connected each others in parallel for resonating an effect of a parallel capacitance.

Abstract: A waveguide diplexer having an electric plane T-junction structure with a resonant iris is disclosed. The waveguide includes: a waveguide having a predetermined shaped cross section; a transmitting filter for preventing to generate a harmonic band and a higher mode in a receiving band by changing impedance to have a low pass characteristic inside the waveguide; a receiving filter for minimizing an insertion loss by changing impedance to have a bandpass characteristic inside the waveguide; an electric plane T-junction for isolating/combining a transmitting signal and a receiving signal without electric interference by connecting the transmitting filter and the receiving filter, and minimizing interference of a frequency transmitted/received through the transmitting filter and the receiving filter; and an impedance converter for differentiating a transmitting port and a receiving port with minimum electric interference to the transmitting filter and the receiving filter by changing the impedance.

Abstract: The present invention relates to a lowpass filter for effectively suppress a spurious in stop-band. The lowpass filter includes an input port microstrip element; an output port microstrip element; a first open-ended microstrip element; a second open-ended microstrip element; a first connector microstrip element; and, a second connector microstrip element. The each open-ended microstrips of the present invention is composed of distributed elements and distributed resistances connected each others in series and operated as a capacity, has a large impedance of the microstrip by low influence of a resistance in case of a low frequency, and has a small impedance of the microstrip by high influence of a resistance value in case of a high frequency. The present invention can effectively suppress the spurious characteristic, which is a disadvantage of the conventional lowpass filter composed of transmission lines at the RF band or the microwave band, by inserting resistance elements in open-ended microstrips.

Abstract: The present invention relates to a lowpass filter for effectively suppress a spurious in stop-band. The lowpass filter includes an input port microstrip element; an output port microstrip element; a first open-ended microstrip element; a second open-ended microstrip element; a first connector microstrip element; and, a second connector microstrip element. The each open-ended microstrips of the present invention is composed of distributed elements and distributed resistances connected each others in series and operated as a capacity, has a large impedance of the microstrip by low influence of a resistance in case of a low frequency, and has a small impedance of the microstrip by high influence of a resistance value in case of a high frequency. The present invention can effectively suppress the spurious characteristic, which is a disadvantage of the conventional lowpass filter composed of transmission lines at the RF band or the microwave band, by inserting resistance elements in open-ended microstrips.