[Amps] high power dual directional coupler

[Geert PA3CSG]

Hello!

I am looking for a design of a directional coupler for HF, 1.8 to 30 MHz 
or if possible 50 MHz.
Sofar I tried the original Bruene, that was not referenced to ground, 
and a tandem coupler were I "smoked" the toroid after a while.
I tried to work one out in LT spice but I don't trust my spice skills ....

Demands:

Frequency range 1.8 - 30 MHz
Several Kw
Coupling in the range of 30dB or more
High directivity
Dual coupling to do Pwr / SWR measurements.

A "how to design" or a complete design would be nice.

Thank you!

73 Geert PA3CSG