Hi
How would be the inductor's property in a small signal ac equivalent circuit.Its obvious that capacitors are considered as shorted when the low frequencies are concerned.
Inductor is always inductor, whatever signal amplitude is (as well as capacitor is always capacitor). As for frequency, inductor is short at low f and open at high f, and capacitor is vice versa.
Like capacitors are taken as short in ac equivalent circuit and open in dc equivalent circuit, inductors can be taken as open in ac equivalent circuit and short in dc equivalent circuit. But it always depends on the frequency you operate in and the purpose of the inductor. For example if you insert an inductor to match a parasitic capacitnce or something you must take into acount the transfer function of the system considering the inductor and the capacitor into acount.