The MLM-3 was designed for automatic measurement of field distribution. The solution enables to observe and understand various field effects occurring along microstrip lines. It is ideal for educational purposes while presenting measuring techniques of standing wave ratio (SWR), reflection coefficients, line input impedances as well as impedance matching.
The device consists of a measuring area and a user-friendly control panel. The measuring area includes a carriage equipped with a near field probe, SMA connector block, measuring table and the PCB clamp.
The controller includes a stepper motor, a control system and an RF detector. The stepper motor drives the carriage with the anti-backlash lead screw positioned along the transmission line with the preset step. The internal or external frequency generator is used for the excitation of a microstrip line. The RF signal detector measures an electric or magnetic field along the line. The location of the probe and the measured value are shown on a display.
Examples of laboratory exercises
1) SWR and the reflection coefficient measurement
An exercise focuses on the study of loaded microstrip lines and reflections. The objective of the exercise is to measure the field distribution, SWR and the reflection coefficient of the microstrip lines with different loads.
2) Input impedances measurement
The aim of this exercise is to measure the input impedances of chosen lines at a fixed cross section. During the exercise students familiarize themselves with a Smith chart. The measured impedance is determined both graphically with the use of Smith chart and by calculation.
3) Half-wave and quarter-wave line properties
The experiment focuses on the properties of a half-wave and a quarter-wave line. For a given frequency students design and make a model of a half-wave line and the quarter-wave transformer with the use of adhesive copper tape and scissors. The design is verified by measurement of SWR at several frequency points.
4) Single-stub tuner matching system
The aim of the exercise is to design a matching system composed of a single-stub tuner with the use of Smith chart. The system is then mapped with the use of an adhesive copper tape and scissors. The design is verified through SWR measurement at several frequency points.
- Compact, robust and user-friendly design
- Very rigid carriage lead – no axial backlash
- High quality parts
- Stable near field probe and PCB mounting
- Various PCB shapes at disposal
- High reproducibility and measurement quality
- User-friendly controller interface
- Internal generator
- Teaching Kit – instructions, lab forms, PCB with loaded microstrip lines, adhesive copper strips