[Antennaware] Antennaware Digest, Vol 131, Issue 1
F. Grant Saviers
grants2 at pacbell.net
Mon Mar 25 18:28:42 EDT 2024
AutoEZ by AC6LA ($ very reasonable) is a great add on to EZNEC. There is a feature called "triple", it generates three plots which show the Z parameters, swr and gain over a range of frequencies and step size and feedline Z you choose. There is a lot more in AutoEZ re optimizing antennas, but that doesn't need to be learned to get "triple" plots.
Grant KZ1W
On Monday, March 25, 2024 at 03:12:30 PM PDT, antennaware-request at contesting.com <antennaware-request at contesting.com> wrote:
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Today's Topics:
1. EZNEC how to model a 4:1 balun (David Gould)
2. Re: EZNEC how to model a 4:1 balun (Joe Subich, W4TV)
3. Re: EZNEC how to model a 4:1 balun (David Gould)
4. Re: EZNEC how to model a 4:1 balun (Jay Terleski)
5. Re: EZNEC how to model a 4:1 balun (David Gould)
----------------------------------------------------------------------
Message: 1
Date: Mon, 25 Mar 2024 17:36:49 +0000
From: David Gould <dave at g3ueg.co.uk>
To: antennaware at contesting.com
Subject: [Antennaware] EZNEC how to model a 4:1 balun
Message-ID: <87913b2a-a758-478a-b768-a00c19aa8fbf at g3ueg.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
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
------------------------------
Message: 2
Date: Mon, 25 Mar 2024 14:23:42 -0400
From: "Joe Subich, W4TV" <lists at subich.com>
To: antennaware at contesting.com
Subject: Re: [Antennaware] EZNEC how to model a 4:1 balun
Message-ID: <e4dcdba1-53ea-4246-9219-d11aa8e43681 at subich.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
> 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
>
------------------------------
Message: 3
Date: Mon, 25 Mar 2024 18:49:38 +0000
From: David Gould <dave at g3ueg.co.uk>
To: antennaware at contesting.com
Subject: Re: [Antennaware] EZNEC how to model a 4:1 balun
Message-ID: <9684ef12-816c-4e6a-aac5-0cc861959459 at g3ueg.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
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
>>
>
>
>
> _______________________________________________
> Antennaware mailing list
> Antennaware at contesting.com
> http://lists.contesting.com/mailman/listinfo/antennaware
------------------------------
Message: 4
Date: Mon, 25 Mar 2024 15:12:02 -0500
From: Jay Terleski <jayt at arraysolutions.com>
To: David Gould <dave at g3ueg.co.uk>
Cc: antennaware at contesting.com
Subject: Re: [Antennaware] EZNEC how to model a 4:1 balun
Message-ID:
<CABzJGbqbqnbL-9fpX_9TqrUDrgqiznHnsO_wEhNeF3P3pxFSCg at mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
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
> >>
> >
> >
> >
> > _______________________________________________
> > Antennaware mailing list
> > Antennaware at contesting.com
> > http://lists.contesting.com/mailman/listinfo/antennaware
>
> _______________________________________________
> Antennaware mailing list
> Antennaware at contesting.com
> http://lists.contesting.com/mailman/listinfo/antennaware
>
------------------------------
Message: 5
Date: Mon, 25 Mar 2024 22:12:01 +0000
From: David Gould <dave at g3ueg.co.uk>
To: antennaware at contesting.com
Subject: Re: [Antennaware] EZNEC how to model a 4:1 balun
Message-ID: <d04bff89-de29-4964-ab1e-27e6ce4bdc2a at g3ueg.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed
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
>>>>
>>>
>>>
>>> _______________________________________________
>>> Antennaware mailing list
>>> Antennaware at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/antennaware
>> _______________________________________________
>> Antennaware mailing list
>> Antennaware at contesting.com
>> http://lists.contesting.com/mailman/listinfo/antennaware
>>
> _______________________________________________
> Antennaware mailing list
> Antennaware at contesting.com
> http://lists.contesting.com/mailman/listinfo/antennaware
------------------------------
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------------------------------
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