Plot magnitude and phase plot

I have one equation in terms of 2 variable A,B, I want to plot magnitude vs phase for different value of A and B .

i don't know how to do this . i was trying but it won't work

for A = -20:1:20

for B = -20:1:20

g = (1 + B*j)/(1 + A*j)

Mag = 20*log10(abs(g))

Phase = angle(g);

plot(Mag,Phase)

hold on

end

end

then obtain value of A and B for particualr value of phase and magnitude

Answer 1

[David Hill]

[A,B]=meshgrid(-20:20);
g=(1+1i*B)./(1+1i*A);
M=20*log10(abs(g));
P=angle(g);
plot(M,P);

[RJS]

Thank you @David Hill, I want to draw this type of figure pls help and then obtain value of A and B for particualr value of phase and magnitude