directional bridge

Agilent sells 300 kHz to 3GHz (75 ohm, typ 86207A) and 300 kHz to 6 GHz (50 ohm, typ. 86205A) directional bridges (from data sheet its characteristics like directional couplers).
Their data sheet is at http://cp.literature.agilent.com/lit...5091-3117E.pdf

Do someone know how they reach this performance ?
Or do someone help with some article or information how can be this performance reched ?

Thanks
g579

It's easy to understand how important companies (Agilent, Anritsu, Rohde&Schwarz etc.) acheived so high performaces. Just open a directional bridge and look inside!
But it isn't easy to replicate!
Broad frequency range and high directivity are strongly related to the quality of the mechanical manufact. As the mechanical assembly is close to a perfect coaxial structure, as the product BW*Directivity will rise.

In this case, my opinion is that there is much to learn looking inside a bridge rather than read an article.

i read the datasheet y posted,the direcitivity is so good,but if i open it to look through,i fear dammage it

Hi sergio mariotti,

1. Unfortunately I have no access to such wideband directional bridges/couplers. I'd be grateful, if you can post or PM a sketch, a photo, or some draft drawing of such units.
2. The mentioned HP/Agilent models not just the upward extensions of the usual directional bridges (I have seen several up to 1 GHz), where the through loss is about 7 dB, BUT its through loss is about ONLY 2 dB which is substantially different from the usual bridge, and rather seems to be a directional coupler.
If you can please post some raw schematic, how it can be reached.
Thanks
g579

Has anybody some real information ?
g579