Dipole antennas and baluns

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Conrad Cardano

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Nov 15, 2025, 8:42:46 AM (3 days ago) Nov 15
to Society of Amateur Radio Astronomers
Hi

I see with a half wave dipole, they use a 1:1 balun.

If I made a fullwave dipole, what balun should I use?

I am interested in 55.3 MHz for meteor detection.

Thank you for helping.

Alex P

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Nov 15, 2025, 9:09:35 AM (3 days ago) Nov 15
to Society of Amateur Radio Astronomers
A "Full Wavelength Dipole" = two half wavelength segments means you will be feeding at the max Z point ~ 2500 ohms.

SO, a 49:1 Z ratio = 7:1 Turns ratio on the matching transformer ( 'balun' )

Alex

Conrad Cardano

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Nov 15, 2025, 9:48:57 AM (3 days ago) Nov 15
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Thank you, Alex.

That’s helpful.

Conrad
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Mike Otte

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Nov 15, 2025, 10:26:11 AM (3 days ago) Nov 15
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Conrad,
Don't go there!
Make a halfwave dipole.   Don't use a  unun ,  extra stuff You don't need.
Impedance will be about 70 ohms which will match  TV coax .  RG-6  or RG-59

Formula is  for lengthen feet   =  468/ freq  in Mhz    so 468/ 55.3 =  8.46 ft  over all length when assembled, so make them longer to start

You are not transmitting so most any piece of plastic with holes in will hold together the junction of the coax and the wires.  The ends can be held with just strings.
Solder junctions would be nice junctions but i have done a lot with wire nuts.

1-2 meters off of the ground.
a  9.73 ft reflector wire  laying on the ground  beneath the dipole will increase your gain.

73
Mike w9ys



On Sat, Nov 15, 2025 at 8:48 AM Conrad Cardano <cardan...@gmail.com> wrote:
Thank you, Alex.

That’s helpful.

Conrad

On Saturday, November 15, 2025, 'Alex P' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:
A "Full Wavelength Dipole" = two half wavelength segments means you will be feeding at the max Z point ~ 2500 ohms.

SO, a 49:1 Z ratio = 7:1 Turns ratio on the matching transformer ( 'balun' )

Alex

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Mike Otte W9YS

Conrad Cardano

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Nov 15, 2025, 11:12:05 AM (3 days ago) Nov 15
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Thank you, Mike

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Lester Veenstra

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Nov 16, 2025, 7:49:55 AM (2 days ago) Nov 16
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Was not following the thread enough to catch the frequency, but a half wave dipole, or odd multiples, will gatch to 50 ohms at particular heights (details available) or more commonly when at the appropriate angle rather than a straight (180 deg)

Still is a bit” height above ground” dependent but in general a more reliable 50 ohms,

In HF up to 6m.  At VHF the Discone antenna is a variation on the angular dipole theme

 

 

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)

les...@veenstras.com

 

452 Stable Ln

Keyser WV 26726 USA

 

GPS: 39.336826 N  78.982287 W (Google)

GPS: 39.33682 N  78.9823741 W (GPSDO)

 

 

Telephones:

Home:            +1-304-289-6057

US cell          +1-304-790-9192

Jamaica cell:    +1-876-456-8898

image001.png
image002.png

Dave Typinski

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7:48 AM (7 hours ago) 7:48 AM
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Hi Lester,

What's the function of the stub at right angles to the plane of the dipole elements?  Is that connected to the signal path anywhere?  And what's inside the gray box?
--
Dave

Lester Veenstra

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10:47 AM (4 hours ago) 10:47 AM
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1:1 balun in box

With the whips supplied thiw will form a dipole with a minimum frequency of 14 MHz  to 54 MHz and beyond.

If this is needed at 40m they supply two loading coils and a matching stub across the feed point (red Banana plugs)

 

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)

 

To get past GMAIL SPAM FILTER reconstruct a return address from

lester  "aptsign"  veenstras  "dot"  com

 

452 Stable Ln

Keyser WV 26726 USA

 

GPS: 39.336826 N  78.982287 W (Google)

GPS: 39.33682 N  78.9823741 W (GPSDO)

 

 

Telephones:

Home:            +1-304-289-6057

US cell          +1-304-790-9192

Jamaica cell:    +1-876-456-8898

image001.png
image002.png

Dave Typinski

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2:13 PM (1 hour ago) 2:13 PM
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Got it, thanks Lester!
--
Dave


On 11/18/25 10:47, 'Lester Veenstra' via Society of Amateur Radio Astronomers wrote:
> 1:1 balun in box
>
> With the whips supplied thiw will form a dipole with a minimum frequency of 14
> MHz to 54 MHz and beyond.
>
> If this is needed at 40m they supply two loading coils and a matching stub
> across the feed point (red Banana plugs)
>
> Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)
>
> To get past GMAIL SPAM FILTER reconstruct a return address from
>
> lester "aptsign" veenstras "dot" com
>
> 452 Stable Ln
>
> Keyser WV 26726 USA
>
> GPS: 39.336826 N 78.982287 W (Google)
>
> GPS: 39.33682 N 78.9823741 W (GPSDO)
>
> Telephones:
>
> Home: +1-304-289-6057
>
> US cell +1-304-790-9192
>
> Jamaica cell: +1-876-456-8898
>
> *From:*sara...@googlegroups.com [mailto:sara...@googlegroups.com] *On Behalf
> Of *Dave Typinski
> *Sent:* Sunday, November 16, 2025 10:28 AM
> *To:* sara...@googlegroups.com
> *Subject:* Re: [SARA] Dipole antennas and baluns
>
> Hi Lester,
>
> What's the function of the stub at right angles to the plane of the dipole
> elements? Is that connected to the signal path anywhere? And what's inside the
> gray box?
> --
> Dave
>
>
> On 11/15/25 11:08, 'Lester Veenstra' via Society of Amateur Radio Astronomers wrote:
>
> Was not following the thread enough to catch the frequency, but a half wave
> dipole, or odd multiples, will gatch to 50 ohms at particular heights
> (details available) or more commonly when at the appropriate angle rather
> than a straight (180 deg)
>
> Still is a bit” height above ground” dependent but in general a more
> reliable 50 ohms,
>
> In HF up to 6m. At VHF the Discone antenna is a variation on the angular
> dipole theme
>
> Lester B Veenstra K1YCM MØYCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG
> CTM1)
>
> les...@veenstras.com <mailto:les...@veenstras.com>
>
> 452 Stable Ln
>
> Keyser WV 26726 USA
>
> GPS: 39.336826 N 78.982287 W (Google)
>
> GPS: 39.33682 N 78.9823741 W (GPSDO)
>
> Telephones:
>
> Home: +1-304-289-6057
>
> US cell +1-304-790-9192
>
> Jamaica cell: +1-876-456-8898
>
> *From:*sara...@googlegroups.com <mailto:sara...@googlegroups.com>
> [mailto:sara...@googlegroups.com] *On Behalf Of *Mike Otte
> *Sent:* Saturday, November 15, 2025 10:26 AM
> *To:* sara...@googlegroups.com <mailto:sara...@googlegroups.com>
> *Subject:* Re: [SARA] Dipole antennas and baluns
>
> Conrad,
>
> Don't go there!
>
> Make a halfwave dipole. Don't use a unun , extra stuff You don't need.
>
> Impedance will be about 70 ohms which will match TV coax . RG-6 or RG-59
>
> Formula is for lengthen feet = 468/ freq in Mhz so 468/ 55.3 = 8.46
> ft over all length when assembled, so make them longer to start
>
> You are not transmitting so most any piece of plastic with holes in will
> hold together the junction of the coax and the wires. The ends can be held
> with just strings.
>
> Solder junctions would be nice junctions but i have done a lot with wire nuts.
>
> 1-2 meters off of the ground.
>
> a 9.73 ft reflector wire laying on the ground beneath the dipole will
> increase your gain.
>
> 73
>
> Mike w9ys
>
> On Sat, Nov 15, 2025 at 8:48 AM Conrad Cardano <cardan...@gmail.com
> <mailto:cardan...@gmail.com>> wrote:
>
> Thank you, Alex.
>
> That’s helpful.
>
> Conrad
>
> On Saturday, November 15, 2025, 'Alex P' via Society of Amateur Radio
> Astronomers <sara...@googlegroups.com
> <mailto:sara...@googlegroups.com>> wrote:
>
> A "Full Wavelength Dipole" = two half wavelength segments means you will
> be feeding at the max Z point ~ 2500 ohms.
>
> SO, a 49:1 Z ratio = 7:1 Turns ratio on the matching transformer ( 'balun' )
>
> Alex
>
> --
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> --
>
> Mike Otte W9YS
>
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