High power combiners at microwave frequencies

I am looking to design high power combiners at 10 -12GHz.
I need a combiner,which can handle 20 watts at above frequencies.
My question is,
1.whether a microstrip based design can handle this? What kind of substrate should be used,so that it can be used for aerospace application.
2.Whether SIW based design is suitable for this purpose.?Which substrate?
3.or only conventional bulky wave guide combiner is the only solution?
As you can judge,the question is very specific,a high power combiner for aerospace application,need to be lighter and reliable.

Bulky waveguide combiners can offer lower loss but they are not your only option; you can use microstrip-based combiners which can handle this power. I do remember that there was a very light MS-DOS software from Rogers which could give you an idea about power handling capabilities of microstrip circuits.
Regarding SIW-based combiners; of course they are superior to their microstrip counterparts in terms of power handling and also they can give you lower loss but designing them could be difficult.

Thanks Hamid
I request members to provide some reference for designing microstrip and SIW based high power combiners at mw frequencies.