| 摘要 |
An impedance matching network for connecting an electrically small antenna 1 to an RF source or load 2 comprises a negative impedance converter (NIC) 3, a pre-matching network 4 coupling the NIC to the antenna, and a post-matching network 9 coupling the NIC converter to the RF source or load. The post-matching network comprises parallel passive branches 5,6 with adjustable inductors 10 or capacitors 11, each branch operating in a different frequency band. The branches may be tuned by the use of variable or switchable capacitors or inductors. The adjustable capacitators may be varactors or MEMS capacitors. The use of a single NIC in conjunction with muliple passive branches reduces the component count, noise figure, and instability. The arrangement of figure 9 is usefull when the frequency separation is small and independent control is required. In an alternative arrangement, a passive matching branch(6, figure10) for a second frequency band may be placed in parallel with a matching branch comprising an NIC. |
