[kellogs]

The network is supposed to actually be ultra wide band

Besides, I was able to get a more decent S11 by halving the dipole: #8928

Thank you!

[kellogs]

Err, resonance ? No sir!

The two 47.9 nH were there to “resonate” the small antenna: 3.9 – j183.6 Ω  @315 MHz

The network is supposed to actually be ultra wide band

Besides, I was able to get a more decent S11 by halving the dipole: #8928

Thank you!

[kellogs]

We are talking about the setup in #8943, yes ?

I don’t get it, S11 looks terrible… I guess I should then disconnect GND between P2 and P3 and call it good 180 degrees difference ? If not, the phase diff also looks terrible to me.

[kellogs]

And doing the full dipole via 1:1 transformer, catastrophe…

 

I am convinced that the matching network impedances were calculated correctly (verified the method against values in the paper), and halving the dipole looks fine as per previous post…

 

[kellogs]

Simulation with lattice network for my halved dipole:

Looks good to me. So halving the dipole as I have done is OK then ?

[kellogs]

Oh, is that so ?… With the GND between P2 and P3 I have noticed that the phase differential goes towards 180 as each of the Z goes towards 0.

The half-dipole .s1p’s that are being used are just the initial .s1p file (real antenna measurement, full dipole) where the impedances have been halved.

Definitely going to use an ideal 1:1 transformer with the initial s1p file.

Thank you for the replies, much appreciated!

[kellogs]

So what I did was to rotate P2 180 degrees and take out the GND between P2 and P3. Don’t really know if it is legit but this way I am getting expected values for both reflection coef and phase difference at dipole arms.

[kellogs]

https://www.fars.k6ya.org/docs/Stearns_K6OIK-Antenna-Impedance-Models.pdf

Page 48, yes ?

This is a bit over my head… so in your schematic, the right side is a narrow band (?) 315 MHz dipole equivalent circuit and that low S11 implies good 180 deg phase diff for the discrete components balun. Right?

[kellogs]

I might want outputs of equal amplitude and 180 degrees out of phase. it does not seem to happen though.

 

I am not so sure that I want to see 180 deg difference in a transient simulation though; the cut=off frequencies are like:

LPF branch of the balun: f_0 + delta_f

HPF branch of the balun: f_0 – delta_f

[kellogs]

Hurrah!

Have I chosen P2 & P3 Z well ? i have made it much larger than the Z range from X1 & X2

Thanks

[kellogs]

Ok, so no way to use the touchstone .s1p files I guess.

[kellogs]

Like this?

phase(S[2,1])-phase(S[3,1])

But how do I convey the port numbering to Qucs ?

[kellogs]

Phase difference between [X1 port 1] and [X2 port 1]

Source port: P1

Thanks

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