RF Engineering

 Figure 1 shows a typical RF radio transmission station and Figure 2 shows a typical RF Radio Receiver Device. While Figure 3 shows the amount of additional loss to be considered in the path loss calculation due to the moving vehicle and building blockage at different location within the broadcast range. In Figure 3, a positive number refers to a power gain, while a negative number refers to a power loss. The transmission station, as shown in Figure 1, up-convert audio frequency into a much higher frequency for long distance broadcast of up to 120km. It has one-stage up-converter mixer with a local oscillator, two bandpass filter, two RF matching network and one matching transformer terminated with the RF transmission antenna. The receiver device, as shown in Figure 2, down-convert RF frequency to audio frequency. It has a low-noise-amplifier (LNA), one bandpass filter(BPF), one lowpass filter(LPF), one down-converter mixer with local oscillator, a pre-amplifier and an audio amplifier. The transmit antenna has a gain, Gt, of +1.2dBi and the receive antenna has a gain, Gr, of -0.7dBi.  Coventry University Version 3.2 Faculty of Engineering and Computing 4 Consideration for building, movable vehicle blocking or cause the attenuation/loss to be increased as per Figure 3 to be taken into account for the FSPL calculation. Student is to determine whether the received signal strength is sufficient and if it is not sufficient what should be done. The receiver sensitivity of the receive section to ensure the circuit to function well requires a minimum of -55dBm while the transmitter have a maximum transmit power of +30dBm. Each student is assigned to use different FM radio frequency channels from 88MHz to 108MHz and a different distance between the transmitter and receiver. The design, analysis, explanation and calculation to include the following: a. Overall transmitter system explanation b. Bandpass filter (BPF) design c. Input matching network (IMN) design using smith chart d. RF power amplifier design e. Output matching network (OMN) design using smith chart f. Antenna - matching quarter wavelength transformer g. Power calculation from output of mixer to transmit antenna chain h. FSPL to the receiver input calculation i. Consideration for parasitic/stray capacitance/inductance, PCB board layout considerations, practical component values selection j. Final complete circuit design with components values specified from output of the up-converter mixer to the transmit antenna. Suggest a practical approach of the implementation. Consideration of using real world practical components for implementation is needed. RF amplifier chosen need to have the S-parameter given in the datasheet. Also take into considerations the stray capacitance and stray inductance present in physical layout of the PCB traces and component placement. Students could also discuss about the various signal fading experienced by FM radio broadcast including passing object such as car, building blockage, etc. State any assumption used clearly and explain why such assumption is used