Previous 13 weeks report

AN_PBI , refer to my blog on how to handle the weeks using date calendar. This can be a Week Calendar, Rank is important

https://community.powerbi.com/t5/Community-Blog/Week-Is-Not-So-Weak-WTD-Last-WTD-and-This-Week-vs-Last-Week/ba-p/1051123

Last 13 week Sales = CALCULATE(SUM(Sales[Net Sales]),FILTER(all('Date'),'Date'[Week Rank]>=min('Date'[Week Rank])-13 && 'Date'[Week Rank]<=max('Date'[Week Rank])))

Last 13 before 13 week Sales = CALCULATE(SUM(Sales[Net Sales]),FILTER(all('Date'),'Date'[Week Rank]>=min('Date'[Week Rank])-26 && 'Date'[Week Rank]<=max('Date'[Week Rank]) -14 ))

You need have few columns

Week Start date = 'Date'[Date]+-1*WEEKDAY('Date'[Date],2)+1
Week End date = 'Date'[Date]+ 7-1*WEEKDAY('Date'[Date],2)
Week Number = WEEKNUM([Date],2)
Week = if('Date'[Week Number]<10,'Date'[Year]*10 & 'Date'[Week Number],'Date'[Year]&'Date'[Week Number])
Week Rank = RANKX(all('Date'),'Date'[Week Start date],,ASC,Dense)

To get the best of the time intelligence function. Make sure you have a date calendar and it has been marked as the date in model view. Also, join it with the date column of your fact/s. Refer :
https://radacad.com/creating-calendar-table-in-power-bi-using-dax-functions
https://www.archerpoint.com/blog/Posts/creating-date-table-power-bi
https://www.sqlbi.com/articles/creating-a-simple-date-table-in-dax/

See if my webinar on Time Intelligence can help: https://community.powerbi.com/t5/Webinars-and-Video-Gallery/PowerBI-Time-Intelligence-Calendar-WTD-YTD-LYTD-Week-Over-Week/m-p/1051626#M184


Appreciate your Kudos.