[Antennaware] EZNEC how to model a 4:1 balun

[David Gould]

Jay,

Thanks again for the elaboration.  I have now got the impedances from 
the SWR plot.  I was just changing the Zo from 50 to 200 and the data 
was not changing, but clicking on the plot again results in the data 
being changed to 200 ohms.

I have now got what I want so many thanks for your help.  What I am 
trying to do is a bit weird but I have my reasons!

73,

Dave  G3UEG



On 25/03/2024 20:12, Jay Terleski wrote:
> Yes, If you use the SWR plot given by EZNEC you can place your curser on
> the frequency you're interested in and it will give you the impedance
> calculated at that frequency.  The source impedance is at the source not at
> the end of the feedline so be careful.  A transmission line will act as a
> transformer unless the source is the same Zo of the transmission line or if
> you are not the 1/2 WL multiple.    I think you are overthinking your
> problem David.   But if you really wanted to get into the details you
> could create a model that had the coax cable feeding your balun included in
> the model and place your source at the radio end of your coax model.
>
>
> Jay Terleski
> Array Solutions
> 214 954 7140
>
>
>
> On Mon, Mar 25, 2024 at 1:49 PM David Gould <dave at g3ueg.co.uk> wrote:
>
>> Thanks to Jay and Joe for the Alternate Zo suggestion.  It certainly
>> gives the revised SWR curve I was expecting.
>>
>> I would also like to know the new impedance after the transformation,
>> which the SWR graph does not provide the data at the bottom is always
>> for the 50ohm plot and not the 200ohm plot.
>>
>> Is there a way to get this additional information?  If not I will
>> investigate the second of Joe's suggestions.
>>
>> 73,
>>
>> Dave G3UEG
>>
>>
>>
>> On 25/03/2024 18:23, Joe Subich, W4TV wrote:
>>>> I am mainly interested in the impedance transformation to the 50 ohm
>>>> feedline coax.
>>> Why not just use Alternate SWR Zo = 200 Ohms?  That will give you the
>>> 50 Ohm SWR after the 4:1 "balun" assuming the balun is a broadband
>>> current balun.
>>>
>>> Otherwise, you can use a second short wire, move your source to it,
>>> and place a *1:4 transformer* between that wire and the location of
>>> your original source.
>>>
>>> 73,
>>>
>>>     ... Joe, W4TV
>>>
>>> On 3/25/2024 1:36 PM, David Gould wrote:
>>>> I am using Pro/2 v 7.0.
>>>>
>>>> I have been through the EZNEC help and the test drive around the
>>>> track, but the examples are all more complex than I am looking for so
>>>> I am having trouble getting to the basics.
>>>>
>>>> I would like to model a variation of a centre fed dipole (over a wide
>>>> frequency range) that has a 4:1 balun at its feed point. Is there an
>>>> example anywhere I could use to copy from?
>>>>
>>>> Currently I am just using a straight wire with the source at 50%
>>>> along. Can I develop from this or do I have to split it into two
>>>> separate wires?
>>>>
>>>> I am mainly interested in the impedance transformation to the 50 ohm
>>>> feedline coax.
>>>>
>>>> Any help would be appreciated.
>>>>
>>>> 73,
>>>>
>>>> Dave  G3UEG
>>>>
>>>
>>>
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