Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_92 ( frequency_mhz VARCHAR, erp_w VARCHAR, call_sign VARCHAR )

### Question ###
Which Frequency MHz has an ERP W larger than 4, and a Call sign of w218ap?

### Accurate SQL ###

SELECT frequency_mhz FROM table_name_92 WHERE erp_w > 4 AND call_sign = "w218ap"