电磁场与微波技术实验天线部分实验一和实验二Word格式.docx
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这时可以采用镜像法来分析。
天线臂与其镜像构成一对称振子,则它在上半平面辐射场与自由空间对称振子的辐射场射相同。
由于使用坡印亭矢量法积分求其辐射功率只需对球面上半部分积分,故其辐射功率为等臂长等电流分布的对称振子的一半,其辐射电阻也为对称振子的一半。
当h<
<
λ时,可认为R≈40。
由于天线到地面的单位长度电容比到对称振子另一个臂的单位长度电容大一倍,则天线的平均特征阻抗也为等臂长对称振子天线的一半,为=60[ln(2h/a)-1]。
【实验步骤】
1.设置仪表为频域模式的回损连接模式后,校正网络分析仪;
2.设置参数并加载被测天线,开始测量输入阻抗;
3.调整测试频率寻找天线的两个谐振点并记录相应阻抗数据;
4.更换不同电径(φ1,φ3,φ9)的天线,分析两个谐振点的阻抗变化情况。
【实验内容及结果截图】
1.设置参数:
BF=600,∆F=25,EF=2600,n=81;
2.短路、开路校准和三种电径天线的截图
1)将导电平面接入开路线进行校正,得到的阻抗点分布:
图1开路校正阻抗分布图
2)将导电平面接入短路线进行校正,得到的阻抗点分布:
图2短路校正阻抗分布图
3)电径为1mm的天线的阻抗点分布:
图3Φ=1mm阻抗分布图
实验数据:
F(Mhz)RL(db)SWRR(Ω)Jx(Ω)
600-0.2568.2020.55-259.
625-0.2375.1115.82-238.
650-0.4438.8324.33-210.
675-0.09183.64.844-204.
700-0.3450.5216.81-199.
725-0.3253.5613.61-183.
750-0.3943.7614.02-167.
775-0.4736.3814.09-151.
800-0.4736.7912.37-141.
825-0.5730.0812.82-129.
850-0.7323.5214.32-119.
875-0.9518.2015.39-106.
900-0.9518.2913.23-97.2
925-1.3612.7415.93-86.4
950-1.789.76317.84-77.3
975-2.158.09518.11-67.9
1000-2.706.47018.89-58.3
1025-3.904.51823.01-49.2
1050-4.593.86623.29-41.9
1075-6.212.91425.59-31.8
1100-8.602.18029.76-23.2
1125-10.01.91430.89-17.6
1150-13.11.56533.48-8.30
1175-17.51.30738.33-1.46(第一谐振点)
1200-18.91.25340.704.251
1225-16.41.35441.6411.11
1250-13.91.49846.0819.15
1275-12.51.61349.1223.91
1300-10.91.78851.2429.81
1325-9.691.97355.2736.05
1350-8.912.11659.1440.71
1375-8.112.29458.5145.44
1400-6.902.64558.3754.02
1425-6.232.90461.5560.90
1450-5.453.29063.6969.92
1475-4.693.78664.2279.89
1500-4.194.22168.7189.98
1525-3.764.68572.53100.0
1550-3.505.01781.69110.1
1575-3.275.36685.39117.9
1600-3.045.76491.98127.8
1625-2.945.947103.1135.6
1650-2.756.352104.4143.4
1675-2.487.029123.6162.9
1700-2.407.258140.3172.3
1725-2.467.093142.4169.5
1750-2.437.168165.3174.8
1775-2.467.085180.7173.6
1800-2.576.799194.8164.9
1825-2.447.164207.2173.8
1850-2.347.444225.3179.1
1875-2.516.960219.0165.2
1900-2.377.374227.9176.4
1925-2.317.535225.5181.9
1950-2.217.882241.9189.3
1975-2.207.905248.1188.6
2000-2.048.542259.4206.2
2025-1.958.902268.8215.4
2050-1.859.382289.9225.8
2075-1.769.862308.2236.7
2100-1.6510.53358.4244.0
2125-1.5611.14377.7258.7
2150-1.4911.64436.4251.1
2175-1.4911.61459.9234.5
2200-1.3912.47510.0239.6
2225-1.3313.03566.1219.2
2250-1.3412.92606.0155.1
2275-1.3013.35633.4146.7
2300-1.2513.84682.381.06
2325-1.2813.51675.5-10.4(第二谐振点)
2350-1.3113.20652.9-69.0
2375-1.3013.29639.8-126.
2400-1.4112.28577.0-145.
2425-1.3812.53562.6-189.
2450-1.4611.91535.6-178.
2475-1.4511.93486.2-230.
2500-1.4911.62478.3-221.
2525-1.5011.59443.8-244.
2550-1.4611.87421.3-268.
2575-1.4212.19416.9-282.
2600-1.3712.69403.6-303.
结果:
F(Mhz)RL(db)SWRR(Ω)Jx(Ω)
由实验数据可得其第一谐振点处频率约为(取最接近点)F1=1175MHz,RL1=-17.5dB,SWR1=1.307,R1=38.33Ω,Jx=-1.46Ω;
第二谐振点处F2=2325MHz,RL2=-1.28dB,SWR2=13.51,R2=675.5Ω,Jx=-10.4Ω。
4)电径为3mm的天线的阻抗点分布:
图4Φ=3mm阻抗分布图
600-0.3450.8412.34-169.
625-0.3352.3210.27-155.
650-0.5829.6315.09-140.
675-0.2470.545.921-135.
700-0.5630.9012.55-129.
725-0.5332.6510.52-120.
750-0.6825.4711.48-109.
775-0.7722.4210.96-98.4
800-0.9019.2811.32-91.2
825-0.9917.3910.78-82.4
850-1.3213.1212.38-74.3
875-1.6710.3913.16-65.0
900-1.909.15213.14-58.4
925-2.516.94514.48-49.2
950-3.654.82918.38-42.3
975-4.334.09119.03-35.5
1000-5.253.40820.13-28.6
1025-7.282.52224.14-20.9
1050-8.672.16626.07-15.6
1075-10.91.78729.02-7.96
1100-13.91.50033.38-1.75
1125-15.91.37936.260.650(第一谐振点)
1150-15.61.39438.168.527
1175-15.51.39844.4314.89
1200-14.41.46549.4219.09
1225-13.31.54452.8522.35
1250-11.91.68159.2427.05
1275-11.01.77463.2429.87
1300-10.71.81967.4830.67
1325-10.21.88870.9932.30
1350-9.781.95972.5334.59
1375-9.282.04474.5637.24
1400-8.792.14172.5641.21
1425-7.882.35175.2547.80
1450-6.862.66179.3757.03
1475-6.202.91682.7664.31
1500-5.503.26187.1873.83
1525-4.833.68796.2285.35
1550-4.513.934113.891.55
1575-4.404.025121.493.29
1600-4.144.269130.199.33
1625-3.904.517145.9103.8
1650-3.754.693154.9107.2
1675-3.395.177176.7117.1
1700-3.175.524210.1115.2
1725-3.315.305220.097.54
1750