Calculate the generic characteristics of a 2 way Wilkinson with stepped line transformers. The results can be transformed to microstrip later.
If you are looking for your ideal Band 11 combiner for those 1.5Kw pallets, well there isn't one.
However you could start with a design 43 Ohm in to 50 Ohm out, n = 1 for in, n = 2 for out, binomial profile and 80 or 40 Ohm sum point. Either a standard 100 or 75 Ohm 1Kw balance resistor is sufficient for those possible fault conditions. Mount on a 12mm, 2oz Polyflon Norclad substrate and you are away.