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# MW Power divider (WPD, GPD), Bandwidth extension techniques

2 months 6 days ago #860 by kakh6739
kakh6739 created the topic: MW Power divider (WPD, GPD), Bandwidth extension techniques
Hello, I am comparing the performance of different power dividers for LTCC substrate at Ka band. For that I am trying different existing BW extension techniques. In the bottom of the page of wilkinson power divider in this website one simple technique for extending bandwidth is shown. One one quarter wave transformer is used on the input port. Can anyone tell me the underlying theory and relevant source of this information? I am also interested in the bandwidth extension techniques for gysel power divider. Thanks in advance. :)

1 month 3 weeks ago #864
Microwaves101 replied the topic: MW Power divider (WPD, GPD), Bandwidth extension techniques
Hello

The bandwidth extension of a WPD is related to impedance transformers.. in a fifty ohm system you are transforming 50 ohms to 25 ohms (two 50 ohm terminations in parallel). For a simple WPD, the arms are 70.7 ohms and act as the entire transformer. Adding a second section either to the input, the outputs or internally means the transformation has additional elements. More elements means more BW. The individual transformers are quarter-wave at center frequency, but if you have two of them you will see that the length becomes quarterwave at F0/2, so you get more bandwidth below the band.

Transformer theory was well known before Wilkinson came along. You can go down a lot of different paths, like equal-ripple, max-flat, etc. There is no singular correct way to do this.

Sorry this is not a great explanation, maybe someone else can expand on this...

Steve

1 month 2 weeks ago #866 by mattskee
mattskee replied the topic: MW Power divider (WPD, GPD), Bandwidth extension techniques
The best reference I personally have for the principles of multi-section or tapered line transformers is Pozar "Microwave Engineering", in the chapter on matching networks. Or there are probably some things online, maybe on this site: look up things like the Cheybshev transformer or Klopfenstein taper.

1 month 1 week ago #869
Microwaves101 replied the topic: MW Power divider (WPD, GPD), Bandwidth extension techniques
For a broadband Gysel, Ali Darwish published a paper that shows 100% bandwidth. The design uses coupled lines. Here is the reference, contact me if you need a copy...

ieeexplore.ieee.org/document/7540294/

I plan to post a page on that combiner in the coming months.

Steve