PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 24; Flight Crew Total 448; Flight Crew Type 239
Communication Breakdown; Situational Awareness; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Conflict NMAC; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Procedure; Aircraft; Human Factors
On date around XA:25 local time I was entering the traffic pattern at ZZZ airport. I had been making radio calls announcing my intentions to over fly the airport at 6;500 feet and enter left traffic for runway XX. After crossing the airport midfield I announced entering a left downwind pattern for runway XX descending to 6;000 feet while looking for traffic in the area. After passing the numbers I started my approach into ZZZ and about 1.25 away I announced turning left base runway XX while scanning for traffic. Then turning base; I looked for traffic and announced that I was on a 1 mile final for runway XX.    About 20 seconds after landing on runway XX I saw Aircraft Y over fly the runway that I just landed on. I cleared the runway and taxied to the ramp area to investigate what happened. During this whole time I didn't hear any announcements from any other traffic in the area. After getting to the ramp I went back through everything to investigate what happened. During which time I noticed that the aircraft wasn't showing up on my ADS-B (Foreflight) until it turned downwind after going around. During the whole time in the pattern I never saw them show up on foreflight. Then I noticed that I was transmitting on 123.7 and not the CTAF frequency 123.0.
Pilot reported transmitting on the wrong frequency contributed to a near mid air collision.