def METHOD_NAME(self):
    """
    Precompute the polar Fourier grid.
    """
    omega0 = 2 * np.pi / (2 * self.nrad - 1)
    dtheta = 2 * np.pi / self.ntheta
    # only need half size of ntheta
    freqs = np.zeros((2, self.ntheta // 2, self.nrad), dtype=self.dtype)
    for i in range(self.ntheta // 2):
        freqs[0, i] = np.cos(i * dtheta)
        freqs[1, i] = np.sin(i * dtheta)
    freqs *= omega0 * np.arange(self.nrad)
    return freqs.reshape(2, -1)