Acoustic Wave and Electromechanical Resonators Concept to Key Applications - Essay Example

Micro Wave Lab Assignment of Affiliation] Table of Contents List of Figures 2 Acknowledgments 3 Parts of the project 4 Power Supply of the Gunn Oscillator 4 Gunn Oscillator 4 Wave-Guide Support 5 Directional Coupler 6 Start Experiment 7 Summary 9 Reference 11 List of Figures Figure 1: Gunn Oscillator symbol 4 Figure 2: Variable Attenuator 5 Figure 3: Directional coupler cross guide 6 Acknowledgments It is useful to acknowledge a variety of individuals who assisted the other or me in one way in order to complete this task. I am heartily thankful to my supervisor who guided me throughout the period and gave guidance on what need to be done for the success of the project. I also take this chance to give much thanks to all the university tutors who inspired me in one way or another to ensure the exercise becomes successful. Finally, many thanks goes to my family as a whole for their valuable time that they offered to me during the entire project period and throughout my study abroad. Parts of the project Power Supply of the Gunn Oscillator GOPS is a component that is designed for the GO. The component helps to power the gun oscillator. The GPOS is used to regulate the amount of power that is required by the Gunn oscillator. Gunn Oscillator Figure 1: Gunn Oscillator symbol The source of the signal that the system uses is termed as the Gunn Oscillator, which is at a signal of 10.5 GHz. the maximum output power that is recommended for the frequency ranges between 20 Mw to 10 Mw, and the recommended range may vary from time to time in different Gunn Oscillators. The output power may as well be varied by varying the voltage supplied that is received by the Gunn Oscillator via the unit cable attached to it (Campanella 2010). Example of the Variable Attenuator Figure 2: Variable Attenuator The devise consists of an adjuster, which helps to regulate the level of the power at the microwave point of input and in making of the measurements of the attenuator. This assignment makes use of the side-vane attenuator that uses the fiberglasses that are plastic in nature having resistive coatings in order to achieve the required attenuation. The fiberglasses are erected vertically with respect to the wave-guide and to the short walls in a parallel manner. The position of the blades on the wave-guide dictates the resulting attenuation of the whole system. Each attenuator is calibrated separately due to differences in the attenuation characteristics. Wave-Guide Support Wave-guide support is a system component that acts as a stand and helps in the system stability. The system supports are in parts, one of the supports is the system base while the other is the plastic piece that is attached to the rod end. Wave-guides can be connected to the support by placing it gently onto the plastic piece of the system located on the rod top. The height of the system support is adjustable with the help of setscrews located on the base of the system. Directional Coupler Figure 3: Directional coupler cross guide For the sake of this assignment, cross-guide couplers were used which consist of two- waveguides that are joined to one another at an angle of 90 degrees. Signals of the microwave that propagates from waveguide couples with microwave signals and finally dictates the coupled signal propagation. Two openings are recommended on the walls. These openings should be cruciform and not circular. The discontinuity that is caused by the cruciform openings is minor as compared to the one caused by the circular openings when both are considered on the same coupling degree. This makes it possible to calculate various parameters for the purpose of measurements. It is worth noting that it is not practical to achieve ideal isolation that exists between the ports two and three and between ports, one and four and some couplings may take place in the process. Using this we can extract a calculable portion of through guide power for measurement purposes. Cross coupler is applicable in measuring of the signal parameters. For example, the transmitter power and signals that are reflected without causing any disturbance to the transmission (Campanella 2010). Start Experiment Before the experiment was started, all the power switches were switched off. The set up was then assembled following the instructions. First, the Gun Oscillator was connected to the GOPS output. Variable attenuator was then connected to the Gunn Oscillator and the crystal detector was finally connected to the SWR meter. Whenever any two components of the system were connected, both the two sides were shut using lock devices. This was to help eradicate the faulty connections of the system. Quick locks are connected by having the holes aligned to one another and inserting the metal pins onto the holes in all the corners. Finally, the plastic flanges are pushed against the pieces and placing the wave-guide connection supports to the Gunn Oscillators (Campanella 2010). When the set up had been assembled, the blade variable attenuators are adjusted to 4.50 mm followed by adjustment of the Gunn Oscillator of the power supply to the minimum value of 1 kHz and a meter range of 10 V. -30 dB range was then finally selected on SWR meter adjusting the SWR gain control knob to the recommended maximum value. 20-hertz bandwidth was then selected followed by powering up of the Gunn Oscillator of the power supply. The set up was waited for 1 minute to warm up then adjustments made to a voltage of 8.5 V. adjustment of the variable attenuator then followed until a reading of -35 dB was attained on the SWR and the distance through which the knob moved was recorded. Since -30 dB ranges was selected, it was easier to obtain -5 dB locating it from the SWR meter. When SWR knob had been adjusted, the signal was maximized and the maximum possible value recorded. A reading of -30 dB was found on the SWR and readings taken. In addition, this acted as the reference point that the experiment was aimed at obtaining. Finally, the GOPC was disconnected from the GOPS. When all these had been done, the new set up was made in order to obtain the coupling factor. Some of the precautions were taken during the experiment to ensure that there is no change in the variable attenuator. Gunn Oscillator was first connected with the output of the GOPS. The variable attenuator was then connected to the Gun Oscillator and finally to directional coupler port 1, crystal detector to the directional coupler port three. Two matched loads were then finally connected to the directional coupler port 2 and directional coupler port 4. Finally, readjustments were made to the SWR Meter Gain control knob and appropriate recommended ranges selected to enhance the reading level of the coupled signals and recordings made. Coupling factor was then calculated and -30 dB ranges on the SWR meter and variable attenuator was adjusted in order to obtain a reading of -30 dB on the SWR meter. Appropriate ranges were selected to help read the relative level of coupled signal and the levels recorded. Finally, disconnecting the power supply of the Gun Oscillator from the power supply cable. Assembling of the final set up followed, in order to find the directional coupler directivity. As was carried out in the initial procedures, gun oscillator was connected to the GOPS and connecting it with the variable attenuator. Next exercise that followed was to connect the variable attenuator with the directional coupler port 1 and port four with the crystal detector. Matched loads were then connected to ports 3 and port 2. Finally, the SWR was connected to the crystal detector and when the assembly had been set, GOPSC and GOPS were reconnected, and measurements recorded. The ranges that allow for the relative levels of the directional coupler ports to be measured were selected. The directional coupler directivity was calculated. When both the coupler factor and the directivity had been obtained, then the GOPS control knob was switched to its minimum and all the power switched turned off and the set up disassembled completely. Summary For the purposes of obtaining the reference readings of the experiment, given set ups were assembled. After assembling the setups, various adjustments were made based on the Variable Attenuator’s blade to a distance of 4.50 mm. Then adjustments of the GOPS followed to minimum voltage and 1 kHz with meter range of 10 V. when all these had been fulfilled, we selected the -30 dB range based on the SWR meter while adjusting the gain control knob that is located in the SWR meter to a value of recommended minimum. Selection of 20-hertz bandwidth then followed. After achieving all the required parameters, powering of the GOPS followed and the SWR meter. For the system to warm up it was left for 1 minute and the GOPS voltage adjusted to a voltage of 8.5. Adjustment of the Variable Attenuator followed to 7.15 mm in order to get a required reading of -35 dB on the systems SWR Meter. Since -30 dB ranges was selected in order to obtain the -35 dB, it is therefore, sufficient to find -5 dB on the systems SWR meter. When the systems center frequency knob is adjusted, the signal is maximized and the maximum values written down as 34.5 dB. A reading of -30 dB on the SWR meter is therefore found by adjusting the VA to 6.10 mm. this acts as the reference point for the set up. This is the reference level we intended to find out from this setup. Finally, the SWR was connected to the crystal detector and when the assembly had been set, GOPSC and GOPS were reconnected, and measurements recorded. When GCK of the systems SWR Meter is not adjusted, appropriate ranges are selected for the coupled signal relative levels of -50 dB. Finally, the coupling factor was calculated and found to be 20 dB. -30 dB ranges was selected on the systems SWR meter further adjustments made with respect to the VA in order to find a reading of -30 dB. Finally, the SWR was connected to the crystal detector and when the assembly had been set, GOPSC and GOPS were reconnected, and measurements recorded. Assembling of the final set up followed, in order to find the directional coupler directivity. Range selection took place in order to measure the signal relative levels of -63 dB and directional coupler directivity calculated and found to be 33 dB. Finally, when both the findings on coupling factor and directivity had been found, the voltage control knob was turned onto the GOPS to the minimum value and all the power switches turned off and the set up disassembled. In as much as the coupling factor seemed correct, the directivity was found to be more than the stated range in a direction of the coupler. I therefore, recommend that this assignment be tried again using different sets of equipment and to ascertain if the same results will be obtained or if the results will be different. Reference Campanella, H. 2010. Acoustic wave and electromechanical resonators concept to key applications. Norwood, MA., Artech House.  Read More