Antenna matching circuit

Abstract

The invention provides an antenna matching circuit. The circuit comprises an adjustable matching circuit connected with an antenna, and a control unit connected with the adjustable matching circuit; the adjustable matching circuit comprises a dielectric substrate, a 50-omega microstrip connecting line, a microstrip transmission line, a microstrip open-circuit branch, an adjustable varactor diode and a capacitor bias circuit; the control unit is used for obtaining the real-time load of the antenna and adjusting the capacitance value of the adjustable varactor diode; the 50-omega microstrip connecting line is an input microstrip connecting line; the microstrip transmission line comprises a first microstrip transmission line, a second microstrip transmission line and a third microstrip transmission line; and the microstrip open-circuit branch envelops the first microstrip open-circuit branch, the second microstrip open-circuit branch and the third microstrip open-circuit branch. Accordingto the invention, when the antenna load changes, the center frequency of the matching circuit can be adjusted, the real part change of the antenna load impedance is 50 omega, the imaginary part change is 50 omega, the output port can be matched in real time, and the antenna matching circuit has the advantages of being flexible in design and easy to tune.

Description

technical field [0001] The invention belongs to the field of microwave devices in electronic technology, in particular to an adjustable antenna matching circuit that changes with load, and a method for calculating variable capacitance by using an improved particle swarm algorithm. Background technique [0002] In wireless communication systems, the input impedance of an antenna is generally considered to be a constant value. However, in practical applications, the input impedance of the antenna varies due to different factors such as frequency, input power, and changes in the external environment. The mismatch between the antenna impedance and the front and back ends of the radio can greatly reduce the power and efficiency of the wireless link. A common solution is to implant a matching network between the antenna and the transmitter / receiver. The traditional matching is to insert a fixed matching network between the signal source and the antenna, which can only match the f...

AI Technical Summary

Problems solved by technology

However, in practical applications, affected by different factors such as frequency, input power, and changes in the external environment, the input impedance of the antenna changes.

The mismatch between the antenna impedance and the front and rear ends of the radio will greatly reduce the power and efficiency of the wireless link. A common solution is to implant a matching network between the antenna and the transmitter / receiver

Traditional matching is to insert a fixed matching network between the signal source and the antenna, which can only achieve matching for fixed frequencies. Once the external environment changes the antenna impedance, the matching network will fail

Moreover, the design of the matching network generally only considers the influence of changes in network parameters on the performance of the antenna, and does not consider the influence of changes in the impedance of the antenna itself, which will reduce the performance of the antenna.

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