3.a A transmitter is located at elevation and horizontal angles (AoA) of 20 o and 25 o respectively. Determine phase difference b/w antenna 1 & 2 and antennas 1 & 4? [6 marks] 3.b The distance from...

3.a A transmitter is located at elevation and horizontal angles


(AoA) of 20 o


and 25 o


respectively. Determine phase


difference b/w antenna 1 & 2 and antennas 1 & 4?


[6 marks]


3.b The distance from transmitter to inferometer is 1km. Determine


the transmitter output power in dbm if the power received by

inferometer
is -80 dBm. Assume isotropic antennas for both


transmitter and receiver?


[12 marks]


3.c The beamwidth of
antenna
for the
inferometer
DF system is


approx. 60 degrees for both elevation and horizontal planes. Draw


a diagram showing in configuration where 360 o


coverage in


the horizontal plane can be achieve

EEET2271 Radar Systems 1 Semester 2, 2014 Page 3 CONTINUED Q2. A superheterodyne receiver is shown in Figure 2. RFin RF Amp RF filter Mixer Lc=8 dB Fm=6 dB IF filter IF Amp IFout f= 12 GHz Gra=10dB Fra=2 dB Lrf=2 dB Br=200 MHz Lif=0.5 dB Bi=45 MHz Gia=20.5 dB Fia=4 dB Local Oscillator f= 11.86 GHz Figure 2 2.a If RFin is -50 dBm and IFout is -10 dBm, determine the signal level and frequency IFout [5 marks] 2.b Calculate the compressive dynamic range (CDR) when the input 1dB compression point, Pin1dB, is -20 dBm. [15 marks] 2.c What are the consequences of reducing the bandwidth of the IF filter, Bi , in terms of system performance? Suggest how to improve the sensitivity of system? [5 marks] Total Marks for Question 2 = 25 marks EEET2271 Radar Systems 1 Semester 2, 2014 Page 4 CONTINUED Q3. Figure 3 shows an interferometer direction finding system with a 9 element planar antenna. The operating frequency is 10 GHz and the antenna elements are separated by /2. All the antenna elements are connected to a phase detector by different lengths of cable (just three cables are shown here). Phase detector ant1 ant2 ant3 ant4 ant5 ant 6 Figure 3 3.a A transmitter is located at elevation and horizontal angles (AoA) of 20 o and 25 o respectively. Determine phase difference b/w antenna 1 & 2 and antennas 1 & 4? [6 marks] 3.b The distance from transmitter to inferometer is 1km. Determine the transmitter output power in dbm if the power received by inferometer is -80 dBm. Assume isotropic antennas for both transmitter and receiver? [12 marks] 3.c The beamwidth of antenna for the inferometer DF system is approx. 60 degrees for both elevation and horizontal planes. Draw a diagram showing in configuration where 360 o coverage in the horizontal plane can be achieved? [7 marks] Total Marks for Question 3 = 25 marks EEET2271 Radar Systems 1 Semester 2, 2014 Page 5 END OF PAPER 400 Q4. An IR system, which is utilized to detect different targets, is shown in Figure 3. Jammer =0.9 T=800 oC A=10,000 cm2 Target Is = 4 m Ao o () = 0.4 () =0.55 NEP=-50 dBm ro = 3 cm Figure 3 4.a Calculate the radiation intensity of the target if the Is = 2.5  [5 marks] 4.b Determine the S/N of system? [6 marks] 4.c Calculate the J/S? [9 marks] 4.d Would this IR receiver be able to detect target, Explain reason? [5 marks] Total Marks for Question 4 = 25 marks End of Questions Figure 2 Total Marks for Question 2 = 25 marks Figure 3 [6 marks] [12 marks] [7 marks] Jammer Figure 3 Total Marks for Question 4 = 25 marks