Based on the information in the question, which is nearly nothing, let's assume the ground stations and satellites are all using circular dish antennas. Then we can use physics to approximate the radiation patterns with an Airy function.
$$I(\theta) = \left(\frac{2J_1(x)}{x} \right)^2 $$
$$x = ka\sin(\theta) $$
where the wavenumber is given by $k = 2\pi/\lambda = 2 \pi f / c $ ($\lambda$ is of course the wavelength, c the speed of light and f is the frequency) and $a$ is the radius of the aperture or in this case the dish.
So say for example at $f =$ 10 GHz and $a =$ 1.5 meters (3 meter diameter) you can plot a simple radiation pattern for a circular aperture or dish. Of course in reality its more complex and ugly, but then you'd have to use a measured radiation pattern.
I'm pretty sure you can do the trigonometry based on the distances to the satellites based on your previous questions.
I have heard numbers like 10 dB for the threshold of interference using satellite TV receivers. I have no idea how close that is, so perhaps 20 dB would be better. These days the signals are digital and there is so much error correction, it's likely to be somewhere in that range.
def I_airy(ka, theta):
x = ka * np.sin(theta)
I = (2.*spj1(x)/x)**2
return I
import numpy as np
import matplotlib.pyplot as plt
from scipy.special import j1 as spj1
halfpi, pi, twopi = [f*np.pi for f in 0.5, 1, 2]
degs, rads = 180/pi, pi/180
f = 10E+09 # Hz
c = 3E+08 # m/s
D = 3.0 # meters
a = 0.5*D
ka = twopi * f * a / c
thetadegs = np.linspace(-2, 2, 600) # Skip Zero!
theta = rads*thetadegs
I = I_airy(ka, theta)
I_db = 10 * np.log10(I)
plt.figure()
plt.subplot(2, 1, 1)
plt.plot(thetadegs, I)
plt.title('linear')
plt.subplot(2, 1, 2)
plt.plot(thetadegs, I_db)
plt.ylim(-30, None)
plt.title('dB')
plt.show()
