gacon149
07-09-2008, 23:19
Mình đang tìm hiểu về Antenna, có một số bài tập mình chưa hiểu lắm, mong các bạn chỉ giúp cho!!!!!
Sau đây là đề bài:
Q1: Design a log-periodic antenna to cover the complete VHI TV band. Use the sign factor T = 0.7 and the highest operating frequency = 3 GHz. Provide a sketch of the five element antenna with all dimension indicated (diagram, calculation and matching dimension) D1 = 10cm.
Q2: An SSB transmitter at 2.27 MHz and 200 W output is connected to an antenna (R1n = 150 Ω) via 75 ft of RG-8A/U cable. Determine:
a. The reflection of coefficient
b. The VSWR
c. The amount of power absorbed by the antenna
Note: the characteristic impedance of RG-8A/U cable is 50Ω and the velocity of wave propagation is 2.07*10^8m/s. 1ft = 0, 3048 m.
Q3: An antenna has a maximum forward gain of 20 dB at 108 MHz center frequency. It’s reverse gain is -5dB. Its beamwith is Π/4 and bandwidth extends from 50-200 MHz.
Calculate:
a. Gain at 22,5° from maximum forward gain
b. F/B ration is dB
Q4: State shortly the following terms:
a. radian pattern
b. Skipping
c. Shadow zone
d. Polazation
Sau đây là đề bài:
Q1: Design a log-periodic antenna to cover the complete VHI TV band. Use the sign factor T = 0.7 and the highest operating frequency = 3 GHz. Provide a sketch of the five element antenna with all dimension indicated (diagram, calculation and matching dimension) D1 = 10cm.
Q2: An SSB transmitter at 2.27 MHz and 200 W output is connected to an antenna (R1n = 150 Ω) via 75 ft of RG-8A/U cable. Determine:
a. The reflection of coefficient
b. The VSWR
c. The amount of power absorbed by the antenna
Note: the characteristic impedance of RG-8A/U cable is 50Ω and the velocity of wave propagation is 2.07*10^8m/s. 1ft = 0, 3048 m.
Q3: An antenna has a maximum forward gain of 20 dB at 108 MHz center frequency. It’s reverse gain is -5dB. Its beamwith is Π/4 and bandwidth extends from 50-200 MHz.
Calculate:
a. Gain at 22,5° from maximum forward gain
b. F/B ration is dB
Q4: State shortly the following terms:
a. radian pattern
b. Skipping
c. Shadow zone
d. Polazation