Low-reflection transmission-line filters with gaussian characteristics

A topology for modeling a transmission line filter having low reflectivity and Gaussian characteristics comprising:

• a ladder network including:
• a plurality of inductive elements aligned in series along a direction of transmission;
• and
• a plurality of shunt branches coupled to the inductive elements and aligned away from the direction of transmission, each shunt branch having a capacitive element and a resistive element coupled in series;
• wherein the topology is used to generate parameter values for the inductive, and capacitive and resistive elements for achieving specified filter characteristics.

A method of designing a transmission line filter having low reflectivity and Gaussian characteristics, the transmission line filter having a number of half cells, each half cell including an inductive element aligned along the transmission line, and a shunt branch off of the transmission line, the shunt branch having a capacitive and a resistive element in series, the method comprising:

• ascertaining values for desired filter parameters;
• deriving formulas for the values of the inductive, capacitive and resistive elements in terms of the desired filter parameters and the number of half-cells;
• selecting a number of half-cells for the filter required to achieve the desired filter parameters;
• and
• estimating lumped element values for the inductive, capacitive, and resistive elements using the selected number of half-cells.

A method of designing a transmission filter having low reflectivity and Gaussian characteristics, the transmission line filter having a number of half cells, each half cell including an inductive element aligned along the transmission line, and a shunt branch off of the transmission line, the shunt branch having a capacitive and a resistive element in series, the method comprising:

• generating a lumped element model of the transmission line filter;
• estimating lumped element values for the inductive, capacitive, and resistive elements;
• and
• approximating the lumped element values using distributed inductance, capacitance, and resistance;
• and
• implementing the distributed inductance, capacitance, and resistance using one of printed-circuit coils, transmission-line sections, and microstrip sections.