Design Of Adaptive Impedance Matching Module And Frequency Adjustable Voltage-controlled Micro Strip Antenna

Ba_xSr_1-xTiO₃（BST）variable capacitors as adjustable devices were used in thepreparation of Adaptive Impedance Matching Module（AIMM）,AIMM combined withRF microwave technology, automatic control technology, the software programmingtechnology, etc. Completed the hardware circuit design of Adjustable output voltageunit, which belongs to Frequency Adjustable Voltage-controlled Micro strip Antenna（FAVMA）. The major conclusions are as follow:1, AIMM: The AIMM module is mainly composed of four modular circuits:Respectively is tunable matching network; Controllable DC/DC regulated power supply;MCU/signal processor and signal power detector. AIMM also contains the directionalcoupler, attenuator, A/D, D/A signal conversion and other aspects. The design of fourmainly circuits are as follows:（1）Ba_xSr_1-xTiO₃（BST）variable capacitors as adjustabledevice were used in the preparation of L tunable matching network;（2） We choseLM2596switch voltage regulator chip as controllable DC/DC regulated power supply;（3）STC89C52signal processor is used for the preparation of MCU chip;（4）Signaldetector is realized power detection method, we chose LTC5505power detector torealize power detector circuit design. Upon completion of the hardware circuit designand debugging. Aglient E5071C vector network analyzer was used to characterize theperformance of the AIMM. Results show that the S11parameter of AIMM changes from-2dB to-9dB around. The ratio of power which absorbed by the antenna with the powerprovided by source increased from40%⁵0%to90%around.2, FAVMA: FAVMA is composed of two parts, respectively is adjustable outputvoltage unit; Micro-strip antenna based on BST variable capacitor. Adjustable outputvoltage unit is the mainly contribution of this article. Adjustable output voltage unitconsist of two parts. They are single-chip microcomputer and adjustable power supply,STC89C52signal processor is used for the preparation of MCU chip. We choseLM2596switch mode regulated power chip to realize adjustable power supply.Adjustable output voltage unit can export bias voltage from0V to60V to controlworking frequency point of electric adjustable micro strip. Upon completion of the hardware circuit design and debugging, Aglient E5071C vector network analyzer wasused to characterize the S11of the module. The test results of voltage-controlledmicro-strip antennas show that when bias voltage is adjusted from0V to52V, itsworking frequency moves from1.47GHz to1.61GHz, return loss below-15dB.