whoever has experience on design microstrip 90-degree hybrid(not use lange coupler) for bandwidth of 4:1 or larger,I just want to know how to realize it?thx.
Yeah odyseus
but with a branch line or a rat race you can achieve a 20% BW. The solution could be find in some articles with that structures modified. But this adds some difficulties in design. I think it is not a simple task.
Mazz
I agree with Mazz's viewpoint.There has some article about how to make a 3-dB microstrip(not stripline) hybrid using modified ratrace
structure with one octove bandwidth but to realize it will have some difficulity.
You can use a double branch line hybrid, there are quite good books on the subject,
the bandwidth of the doubble branch line is greater than the 90 deg branch line hybrid so it should fit your needs, if you can not find litterature mail me and i will find it in a few days.