I originally based the dimensions and layout on the files in the "Sponsor_Templates" zip file (1303 x 326) but converted it to fit on a 1024 x 1024 canvas.
Fabric_Logo_Submission: 1303 x 326
Fabric_Logo_Submission2: 1024 x 1024
Fabric_Logo_Submission: 1303 x 326
Fabric_Logo_Submission2: 1024 x 1024