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Dynamic Pre-Matching Function
(MT993 Series Feature)

The Maury Windows® 98/2000/XP PC based application software (MT993 Series) includes a dynamic pre-matching function for Maury's standard automated tuners. With this function, one tuner transforms the lowest impedance to a higher value, and the second tuner brings it to 50 ohms. The combination of the two tuners will generate a reflection factor of almost unity at the reference plane of the tuner connector (provided that there is very small loss between the connector and the first probe of the tuner). Obtaining the near unity reflection factor allows accurate measurement of devices with less than 0.5 ohms impedance. This technique also permits tuning to any phase. The absence of phase tuning capability is the main limitation of standard 1/4-wave transformers or pre-matched probes.

A secondary benefit of this technique is that the two tuners can be operated at increasinly lower VSWR as their combined reflection factor approaches near unity. This allows higher power measurements to be made from the same setup.

Block Diagram Interface (Figure 3-1)

Complete system configuration (including test equipment, equipment drivers, measurement parameters, and test conditions) can be performed from this GRAPHICAL INTERFACE display. It is an interactive display, from which users can configure, save, recall, and control various test setups for different applications. The block diagram shown in Figure 3-1 is a typical setup for dynamic pre-matching. Each icon in the block diagram represents actual instruments in the test setup, and each is configurable to match the characteristics of those instruments. Each instrument represented in the block diagram can be independently turned on or off as desired, to simulate various operating conditions.

Interactive Measurement Mode (Figure 3-2)

Figure 3-2 shows before and after views of the pre-matching function in a power measurement mode display.