Hebrew Translation for "The Faithful God" - האל הנאמן

I am looking for the standalone translation of "The Faithful God" or "God is Faithful". Specifically, from Duet. 7:9 the original text for "the faithful God" is האל הנאמן but the root words are אל and ָאַמן. What I don't understand is the addition of the the ה character to אל (’ēl). I just want ot get it right- so what is the best way to say that "The Faithful God" or thereabouts as a standalone couple of words? Can it be done with האל הנאמן? Let me know and thank you for your help.