Nowadays the use of UAVs (Unmaned Aerial Vehicle) is getting widespread in different walks of life. At present, these vehicles are allowed to use the airspace with some restriction concerned height and area but regardless any mounting demands. For this reason it is rather hard to detect them by radar systems. However because of the growing number of these vehicles it has become necessary to install automatic sense and avoid systems on the board of them, in order to decrease the probablity of accidents. Currently the development of these systems are in resarch stadium. In my thesis I introduce the probable building and the method of the operation of the sense and avoid system, and I particularise the course of proceedings of the design and the implementation of a four-channel receiver amplifier block which is one part of the system creadted by myself. I also present and summerize the most important measurment results of the semester have been done on the constructed equipment. In my thesis I particulary deal with the examination of the phase difference between channels of the amplifiers, and how it changes by the temperature.