Broad band diplexer using suspended strip-line capacitor technology

摘要

A broad band diplexer employing suspended strip-line capacitors is disclosed. The diplexer has a low pass filter circuit and a high band pass filter circuit. The high band pass filter circuit has a first set of conductive pathways formed on the first surface of a suspended dielectric substrate, a second conductive pathway formed on the second surface of the substrate such that first and second conductive pathways are capacitively coupled, and plural resonators. The high pass filter circuit provides plural transmission poles within the band of operation exceeding the number of resonators.

主权项

1. A diplexer, comprising:
a top ground plate and a bottom ground plate spaced apart to form one or more cavities; at least one dielectric substrate suspended between the top and bottom ground plates; a common port coupled to the at least one substrate; a low frequency port coupled to the at least one substrate; a high frequency port coupled to the at least one substrate; a low pass filter section comprising a first transmission line structure, formed on the substrate and electrically connecting the low frequency port and the common port, and one or more low frequency resonator structures, each of the one or more low frequency resonator structures comprising a strip-line formed on a first surface of the substrate and coupled to the first transmission line structure; and a high pass filter section comprising a second transmission line structure formed on the first surface of the at least one substrate, and a third transmission line structure formed on a second surface of the substrate and having at least one portion overlapping and immediately opposite a corresponding portion of the second transmission line structure and capacitively coupled thereto, a fourth transmission line structure formed on the first surface and having at least one portion overlapping and immediately opposite a corresponding portion of the third transmission line structure and capacitively coupled thereto, the second, third, and fourth transmission line structures together electrically connecting the high frequency port and the common port, the high pass filter section further comprising one or more high frequency resonator structures formed on the substrate and coupled to at least one of the second and third transmission line structures; wherein the one or more high frequency resonator structures comprise plural strip-line resonators alternating on the first and second sides of the at least one substrate; and wherein the plural resonators comprise:
a first resonator comprising a first open ended strip-line formed on the second surface of the substrate, the first resonator electrically shunted to the third transmission line structure,a second resonator comprising a second open ended strip-line formed on the first surface of the substrate, the second resonator electrically shunted to the second transmission line structure; and,a third resonator comprising a third open ended strip-line formed on the surface, the third resonator electrically shunted to the fourth transmission line structure.