import numpy as np
import matplotlib.pyplot as plt
theta = np.linspace(0, 2*np.pi, 1000) # 极角范围
frequency = 5.8e9 # ETC频率(5.8GHz)
wavelength = 3e8 / frequency # 波长
def radiation_pattern(theta):
main_lobe = np.cos(theta) ** 20 # 主瓣形状
side_lobe = 0.1 * np.sin(2*theta) # 旁瓣扰动
return np.abs(main_lobe + side_lobe)
r = radiation_pattern(theta) # 辐射强度
fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot(111, polar=True)
ax.plot(theta, r, color='red', linewidth=2)
ax.set_title("ETC RF信号辐射方向图(示例,5.8GHz)", pad=20)
ax.grid(True)
ax.set_theta_zero_location('N') # 主瓣指向正上方(类似真实ETC天线布局)
plt.show()