return loss bridge, more about construction, how?

[jaya000]

return loss bridge

I hv seen the return loss bridge here.
https://www.webx.dk/oz2cpu/radios/swr-bridge.htm
From the schematics & construction i am not able to understand the construction of
the return loss bridge.
I want to make one like this.

 

[xxargs]

return loss bridge schematic

Is a 'standard' weathstone bridge

toroid-line is a balun to make possible measure unbalance between each 'leg' in bridge width extern unbalanced detectors/reciver/RSSI-circurit...

size, quality and frequency range on toroids in balun make limits on usable bandwith on bridge. - i think in your example PDF:s using high frequency toroids inside big outer toroids working for lower frequency to make bridge working between 1 MHz - 1 GHz range - resistive bridge itself can going from DC to very high frequency if you using floating, balanced detectors.

If you using reciver/RSSI-circurit with well balanced input (i think AD8307 or simular high dynamic logaritmic detectors) i think you can skip this toroid line.

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Pity AD8302 has not balanced input... otherwise I think possibly make some intresting return loss measure bridge with measure of phase angle over very wide frequency range from near DC to 2.7 GHz... - and big step to build own network analyze - if known return loss and phase angle (after open, short, load calibrate) - is possible to calculate type of complex loads ie. value on cap/ind and value of resistance on load.

data scheet on AD8302 show vector reflectometer on side 20, but builds on directivity coupler - but build directivity coupler from near DC to 3 GHz is not easy task and need same skillness as build coupler inside hp/agilent 8753 Network analyzer...

 

[jaya000]

reflectometer bridge ad8307

Thanks xxargs,
I hv read ur suggestions carefully.
Now i just want to know how they hv made connections after 51 ohms. from schematic & built i am not able to get the connection. They say that they hv used 4 small beads inside & big outside. But how they must hv done internal layout ?
I am also interested in making bridge from AD 8302/AD8307. But i wish to make a bridge which can measure gain & return loss at a time by using 2 detectors.
This requirement is exactly as seen in the the following link