{Explain plz} Corporate feed network..

[kela3kela]

Dear members.
Two different corporate feeding networks are shown below,

Could someone plz explain to me how the impedances are being matched to main feed of 50ohm?


Figure 1

Figure 2

Awaiting replies

Regards

 

[reidintransit]

figure 1. 50 ohms in series with split to two 100 ohm lines is good match, then lambda/4 tranformer 70.7 ohm to improve match between 50 and 100 ohm in series. split from 50 to 70.7 not great match since 2 of 70.7 ohms are seen as 35.35 ohms = ran out of room or found it to be good enough. Not all existing designs are optimised for best performance. Engineering is a game of tradeoffs.

 

[kela3kela]

Thnx @redidintransit..Its clear now...What about the second fig?

 

[kela3kela]

Courtesy @tyassin For fig.2.
"Each antenna feed point must have an input impedance of 50 ohms. As shown on the drawing each line from each antenna feed point must/is 50 ohm lines. We just need to analyse half of the circuit as it is symmetrical. Lets take the top half. Here we have two 50 ohm lines coming from each antenna. These are each connected to a 70.7 ohm line, where each line is a quarter-wave transformer. This will transform each line up to a 100 ohm. Now we have two 100 ohm lines in parallel...this is then 50 ohms. Now this is connected to a 50 ohm line down to another quarter-wave transformer(70.7 ohm), again it is transformed up to 100 ohm.
Now the same thing happens to the bottom half of the circuit, so here we also end up with a 100 ohm. So we have two 100 ohms in parallel which is again 50 ohm and then a 50 ohm line out to where ever and you have a 50 ohm match.

I hope this helped. "

 

[kela3kela]

Can someone plz tell me how can I make the above corporate feed network(fig 2) in Ansoft Designer for 60 GHz frequency??

 

[Bob60]

Ansoft like another 2.5D simulation CADs (ADS, Geneeys, MWO ) will be not precise. I would recommended CST MICROWAVE STUDIO it would be match better as specially for 60GHz.

 

[reidintransit]

Correction to my previous post: Split from 50 to two 70.7 is not a bad match since quarter wave transforms to 100 ohms for each section right at the junction. This means the 50 ohm at the junction sees two 100 ohm impedances at the 70.7 ohm lines. 70.7 is used because it is the geometric mean of the two impedances being matched. Zt = sqrt(ZL*Z0).

 

[kela3kela]

@Bob60
Im trying to implement it CST MWS but Im not getting any good results...Can u help?? Inbox me if so...

@reidintranst
Thnx for correction.

 

[Bob60]

Im not getting any good results.

sounds funny... CST is advanced calculator if you get multiplying result 2x2=5 it means that something wrong with parameters solvers and so on. If seriously drop me project I `ll try to check ASAP.