Situational Awareness; Communication Breakdown
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem
Human Factors; Aircraft
Without selection RTU changed off original frequency on base into ATL.  We noticed voice change and selected last remembered frequency.  Turned onto final [and] asked for correct frequency.  Returned to Approach.  If continued we would have caused a conflict with 27L approach.  Last specified instruction was to expect to follow B757 with one more turn so we felt that was the best way to avoid the other aircraft on final.
While receiving vectors from ATL Approach on a heading of 360 to intercept Runway 28 final approach course; frequency dropped out on its own.  The crew attempted to re establish comm but frequency had been lost. Contacted prior frequency and turned to intercept but overshot final to the north.  We re established on a heading of 230 to intercept final for Runway 28.Overshot final on runway 28 because of loss of frequency and consequent lack of final vector to join final app course.  Put same frequency on radio 1 as well as on radio 2 in case last frequency on radio 1 goes out.
CRJ200 Flight crew reports an inadvertent frequency change during approach causing an localizer overshoot before communication can be reestablished. See ACN 1105158.