Patent ID: 6590538
Filing Date: 2003-07-08
Classification: H01Q,H03H,H04B

Abstract:
An antenna apparatus in a portable radio apparatus comprising:an antenna element mounted which receives electrical power from a radio circuit in the portable radio apparatus and matching in a predetermined frequency band; and a matching circuit which matches impedance of the antenna element and internal impedance of the radio circuit, wherein the matching circuit has a match characteristic to conjugately match the internal impedance of the radio circuit and input impedance from the radio circuit, to satisfy the following equations: Zin=(Â¼)Â·(ZaZc/(Za+Zc)); Pin=(Â½)Â·Re[Zinâ€²I1I1*]; I1=Vg/(Zg+Zin); Pin=(Â½)Â·(|Vg|2Â·Re(Zin)/|Zg+Zin|2)=PavÂ·S; Pav=|Vg|2/8Re(Zg); and S=(4Re(Zg)Â·Re(Zin))/|Zg+Zin|2&lE;1, where, Zin represents input impedance from the radio circuit;Za represents impedance of the antenna element; Zc represents impedance of the matching circuit provided in parallel with the impedance of the antenna element Za; Zg represents internal impedance of the radio circuit; Vg represents power supply; Pin represents input power; and * represents complex conjugate.