Radio antenna matching circuit
AssigneeSmarteq Wireless AB
InventorZsolt Barna
Life of this patent
Estimating the term…
Abstract
Matching circuit for radio antenna that functions on a two-frequency band which are spaced approximately at a distance of one octave, wherein the upper band is broad. For instance, the first frequency band may be 890-940 MHz and the other band 1710-2200 MHz. The radiator may be a dipole or a monopole over the earth plane, whose bandwidth is sufficient for the first band. The larger bandwidth for the second band is obtained with a transmission circuit that moves and forms the frequency curve stepwise in the Smith chart. When necessary, the matching circuit includes a broadband Balun transformer in addition to said matching circuit.
Claims9
A transmission circuit, comprising a first port (A—A) and a second port (F—F) for use with a radiator for radio waves within a first frequency band where a radiation resistance of the radiator is low, and a second frequency band where a radiation resistance of the radiator is high, said first port (A—A) of the transmission circuit for matching to an impedance of the radiator, said second port (F—F) for matching to an impedance of a feeder line, wherein the second frequency band lies approximately one octave higher than the first frequency band, wherein a real part of the impedance at the second port (F—F) is greater than a real part of the impedance at the first port (A—A) within the first frequency band, and wherein a real part of the impedance at the second port (F—F) is smaller than a real part of the impedance at the first port (A—A) within the second frequency band, said transmission circuit having components including, when viewed from said first port (A—A) to said second port (F—F), at least one parallel capacitor, at least one series inductance, at least one series capacitor, at least one phase shift line and at least one parallel capacitor, in that order, said components transforming the impedance in the first and second frequency bands at the first port (A—A) to the second port (F—F) so that the impedance at the second port (F—F) has approximately the same value within both frequency bands.
A transmission circuit, comprising:
- a first port (A—A) and a second port (F—F) for use with a radiator for radio waves within a first frequency band where a radiation resistance of the radiator is low, and a second frequency band where a radiation resistance of the radiator is high, said first port (A—A) of the transmission circuit for matching to an impedance of the radiator, the second port (F—F) for matching to an impedance of a radio apparatus, wherein the second frequency band lies approximately one octave higher than the first frequency band, wherein a real part of the impedance at the second port (F—F) is greater than a real part of the impedance at the first port (A—A) within the first frequency band, and wherein a real part of the impedance at the second port (F—F) is smaller than a real part of the impedance at the first port (A—A) within the second frequency band, said transmission circuit having components including, when viewed from the first port (A—A) to the second port (F—F), at least one parallel capacitor, at least one series inductance, at least one series capacitor, at least one phase shift line and at least one parallel capacitor, in that order, said components transforming the impedance in the first and second frequency bands at the first port (A—A) to the second port (F—F) so that the impedance at the second port (F—F) has approximately the same value within both frequency bands.
Dependencies are inferred from the claim text.