The Design Of RF Part Of The Virtual Scalar Network Analyzer

With the large of application of computer, virtual device technique is developed very much, virtual multimeter appeared, virtual scope appeared, and even virtual laboratory appeared. These devices has their common trait that is low cost, convenient operation, and getting data precisely, deal with data quickly with using computer. Moreover, with communication technique is developing at very fast speed, RF technique is more important, so more RF instrument is needed. Think of that the absolute value of S parametric is enough in most condition, thus, we designed virtual scalar network analyzer, moreover, analyzing and making RF model block is main work in my paper.The character of virtual scalar network analyzer is that the cost of developing and maintenance is low, could be reconfigured, could be used conveniently, etc. the design method is that, it was analyzed firstly in the theory, then simulated for verification, fabricated at last. We used Simulink and GUI of MATLAB to simulate the whole system, after simulation, the feasibility is approved. We used ADS 2003A to simulate RF module, in the fabrication of RF module, it make the circuit design be more simple, and be more precise. Meantime, reference to the thinking of the error calibration in network analyzer, we designed the error calibration in this system. We could achieve it using computer easily, and it could not only improve the measure precise, but also saved the cost.In this paper, besides of the design and simulation of the scalar network analyzer system, the part of RF module is our another important work, it includes: first, we analyzed the resistance power divider and Wilkinson power divider in theory, and made a Wilkinson power divider which has 900MHz center frequency. Moreover, based on this one, we used PBG structure to broad the power divider's band wide. Second, we discussed the branch-line directional coupler, parallel line directional coupler, and Lange directional coupler in several. And we fabricate branch-line directional coupler in micro strip structure. Third, we analyzed the design method of low noise amplifier, and then made a LNA, and its noise figure is less than 1.6. Fourth, we discussed the method of making VCO, and design a VCO whose frequency is from 850MHz to 950MHz.