Consider an input signal x_total and the complex envelope of an output signal y_total in MATLAB: 

    T = 10e-9;                            
    f_s = 1e12;                                             
    t = [0 : 1/f_s : T]';                                       
    f_c = 11.5e9;                      
                                   
    f_1 = -0.1e9;                                                            
    f_2 = 0;                                                                 
    f   = [f_1 f_2]';
    
    x_1 = 1*sin(2*pi*(f_c + f(1))*t);                                        
    x_2 = 1*sin(2*pi*(f_c + f(2))*t);                                       
    x_total = x_1 + x_2;
    
    y_envelope = A_out .* exp(1i* theta) .* exp(1i*Phi);

2 Questions:

How do I plot the spectrum of x_total? X_total = fft(x_total) yields a complex result. I want the x-axis of my spectrum to be in Hertz. 

And I want to plot the spectrum of my output signal y_total as well. From the complex envelope, can I say y_total = A_out*sin(2*pi*f_c*t + (theta+Phi))?