The study to find the best shape possible for the quenching function of a super-regenerative receiver

Abstract

This project is concerned with the study to find the best shape possible for the quenching function of a super-regenerative receiver. The most important aspects of the project include; the task involving the design and construction of a tuned oscillator with a feedback loop transmitting a carrier signal, an LC tuned circuit which picks up the carrier signal being transmitted, and the construction of a super-regenerative receiver. The frequency of operation (carrier signal) used in this project is 192kHz. Loop antennas of similar dimensions are used for both the tuned oscillator and the LC tuned circuit in the transmitter and receiver side respectively. For the super-regenerative receiver, another loop antenna was built having a smaller size when compared to the previous two loop antennas mentioned. This is because if it was the same size of the other antennas, it will radiate and will be picked up by the first loop in the amplifier, with the result that it will oscillate. Although this loop antenna has a smaller coil, it was of utmost importance that it will be of the same resonant circuit as the other loops. This loop was positioned to be at right angle to the loop antenna of the common emitter amplifier so that they will not couple energy from one to the other. The aim of the project is mainly to design and create a working plan, study different forms of quenching and measure the target parameters so as to produce a good receiving system, having the maximum possible range limited only by sensitivity of the circuit. Testing is carried out along the period of constructing and implementation of the various important aspects of the project, as well as after the functionality of the whole project. The results obtained through this project were a wide range between the transmitter and receiver of over 2m, with the latter having a quality receiving system consisting of good sensitivity and selectivity. Previously, during the course of Electrical and Electronic Engineering, some experience was gained since as a group we worked and implemented a very simple transmitter and receiver. A transmitter with a carrier signal of 1MHz was used. This was transmitted through a wire of a length of around 30cm at the output of a Hartley oscillator so that the signal could be captured using another antenna (another piece of wire of the same length as that of the transmitter). From this thesis, I experienced the complexity required in antenna design to transmit at a decent distance with low noise for a carrier signal of a frequency mentioned above.