Yagi Patch 1420MHz NEC model ?

[Alex P]

Anyone have a model of this ?

Thanks,

Alex

[fasleitung3]

As you might guess we have one of these as this photo has been taken by me :-)

Is there anything specific you would like to know about this antenna?

Cheers,

Wolfgang

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[Marcus D. Leech]

On 01/12/2023 11:19, 'fasleitung3' via Society of Amateur Radio Astronomers wrote:

As you might guess we have one of these as this photo has been taken by me :-)

Is there anything specific you would like to know about this antenna?

Cheers,

Wolfgang

It is very pretty, for sure.  It has that 1950s "Death Ray" vibe to it :)

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/197ca863b8192488be196ca6e80d374433166a7a.camel%40googlemail.com.

[b alex pettit jr]

Hello Wolfgang,

Did not know that :)

Do you have the gain/elevation(az)  radiation pattern plot ?

( and/or the NEC model file ? )

Thanks,

Alex

[tedcl...@gmail.com]

In Wolfgang's

      https://astropeiler.de/wp-content/uploads/2020/01/Hydrogen_4.pdf

I think his "Patch Yagi" antenna came from

      "1.4GHz radio astronomy disk antenna (21cm) Gain: 11.9dbi"

      on

      http://www.falk-on-tour.de/Antennen.html

[fasleitung3]

Actually the measured pattern is in:

https://astropeiler.de/wp-content/uploads/2020/01/Hydrogen_1.pdf

under 7.8.3

I don't have a NEC model for it.

Wolfgang

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[b alex pettit jr]

Thank You.

That matches nicely with a Grid/Patch model I found.

Regards,

Alex

=====================

[fasleitung3]

Just as a fun fact:

Here is an "extended" version. Designed and manufactured by Jean Marie Brieussel, F6ETU. This has 1 reflector and 26 directors. It has a FWHM of 20° and a gain of ~ 19 dBi.

I have not done a lot with it yet but it certainly shows nice hydrogen spectra....

Wolfgang

[Andrew Thornett]

How does one of these compare to a dish?

Sent from Outlook for Android

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From: 'fasleitung3' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: Friday, December 1, 2023 8:48:49 PM
To: sara...@googlegroups.com <sara...@googlegroups.com>
Subject: Re: [SARA] Yagi Patch 1420MHz NEC model ?

 

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[Marcus D. Leech]

On 01/12/2023 15:54, 'Andrew Thornett' via Society of Amateur Radio Astronomers wrote:

How does one of these compare to a dish?

There's a "crossover point" where a Yagi becomes less attractive because of length (and attendant mechanical issues)
  compared to a dish.

But even between Yagi and Dish, there are other approaches -- like a "can" feed augmented with a conical extension
  that brings the aperture out to about 25-35cm.  I actually had a 30cm extension made by my local sheet-metal
  shop for not very much $$ -- works fine, it has the advantage over a Yagi that it has lower back and sidelobes than
  a Yagi of the same notional forward gain.

To view this discussion on the web visit https://groups.google.com/d/msgid/sara-list/CWXP123MB3653E6B38D2AC60D3E5EFC5CFF81A%40CWXP123MB3653.GBRP123.PROD.OUTLOOK.COM.

[b alex pettit jr]

* That is not Trivial : Spillover of 290K surroundings adds substantially to the noise of the system.

On Friday, December 1, 2023 at 04:06:59 PM EST, Marcus D. Leech <patchv...@gmail.com> wrote:

On 01/12/2023 15:54, 'Andrew Thornett' via Society of Amateur Radio Astronomers wrote:

How does one of these compare to a dish?

There's a "crossover point" where a Yagi becomes less attractive because of length (and attendant mechanical issues)
  compared to a dish.

But even between Yagi and Dish, there are other approaches -- like a "can" feed augmented with a conical extension
  that brings the aperture out to about 25-35cm.  I actually had a 30cm extension made by my local sheet-metal

  shop for not very much $$ -- works fine, 

*  it has the advantage over a Yagi that it has lower back and sidelobes than

[Marcus D. Leech]

On 01/12/2023 16:11, 'b alex pettit jr' via Society of Amateur Radio Astronomers wrote:

* That is not Trivial : Spillover of 290K surroundings adds substantially to the noise of the system.

Agreed.

Here's a couple of "can" feeds with 25cm-diameter extensions that I had made:

https://photos.app.goo.gl/jTTy8CS2oRZdHyfKA

On Friday, December 1, 2023 at 04:06:59 PM EST, Marcus D. Leech <patchv...@gmail.com> wrote:

On 01/12/2023 15:54, 'Andrew Thornett' via Society of Amateur Radio Astronomers wrote:

How does one of these compare to a dish?

There's a "crossover point" where a Yagi becomes less attractive because of length (and attendant mechanical issues)
  compared to a dish.

But even between Yagi and Dish, there are other approaches -- like a "can" feed augmented with a conical extension
  that brings the aperture out to about 25-35cm.  I actually had a 30cm extension made by my local sheet-metal

  shop for not very much $$ -- works fine, 

*  it has the advantage over a Yagi that it has lower back and sidelobes than

            a Yagi of the same notional forward gain.

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[bsn...@gmail.com]

Thanks to the "falk-on-tour"  link even though I don't read German.

Interesting that the shape of the director elements doesn't seem to effect the gain. Not surprisingly, the number of the elements does.

Were it possible to properly (mathematically) reduce the size of disk directors, one could have a Log Periodic Disc antenna.

I have some some small experience with log periodic antennas at HF frequencies. 

They have large gain in a very narrow beam.

Would such an antenna be of value to the amateur RA?

Anyway, interesting disucussion......thanks....bill....

[b alex pettit jr]

It all depends on the target .. 

For a distributed source as Hydrogen Line RF,  an antenna with high gain and small area is not optimal.

( Somewhat like trying to optically view a dim nebula with a small diameter high f/ number telescope )

On Friday, December 1, 2023 at 05:32:52 PM EST, bsn...@gmail.com <bsn...@gmail.com> wrote:

Thanks to the "falk-on-tour"  link even though I don't read German.

Interesting that the shape of the director elements doesn't seem to effect the gain. Not surprisingly, the number of the elements does.

Were it possible to properly (mathematically) reduce the size of disk directors, one could have a Log Periodic Disc antenna.

I have some some small experience with log periodic antennas at HF frequencies.

They have large gain in a very narrow beam.

Would such an antenna be of value to the amateur RA?

Anyway, interesting discussion......thanks....bill....

[Marko Cebokli]

Can you share that model (or a link to it)?

2023-12-01 21:39, je 'b alex pettit jr' via Society of Amateur Radio Astronomers napisal

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[b alex pettit jr]

Hello Marko,

That is included in the Example Models  of   4nec2

File Attached

( it is tuned to146MHz, but the radiation  pattern is valid  )

Regards,

Alex

=======================================================

On Saturday, December 2, 2023 at 12:21:03 AM EST, Marko Cebokli <s57...@hamradio.si> wrote:

Can you share that model (or a link to it)?

================================================================

2023-12-01 21:39, je 'b alex pettit jr' via Society of Amateur Radio Astronomers

 

Thank You.

 

That matches nicely with a Grid/Patch model I found.

 

Regards,

Alex

 

=====================

 

 

[Marko Cebokli]

Thanks!  Will look into 4nec2.

2023-12-02 09:03, je 'b alex pettit jr' via Society of Amateur Radio Astronomers napisal

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[jjm_...@wanadoo.fr]

Hi Wolfgang, all

 

Yes this antenna works well for RA on 21cm. Thank you for this comment.

It is designed for low sidelobes and low temperature.

Here find 2 links as example of a small 21cm RT.

Observation of a meridian transits of our Galaxy and sun,  photo  (at home)

https://groups.io/g/radioastronomie-amateur/message/2108

 

 

with a small example of 1 image  (sorry, it it’s a French list ). Composite image with the Galaxy plan and sun transits On 24h.

https://groups.io/g/radioastronomie-amateur/message/2122

 

The transit was approximately at the +54° declination  (small circle UTC color coded )

 

o I am working to improve  the processing to catch better images and presentation of the data versus time (mor integration time at 4min works also well).

 

73 and regards, JJ F1EHN.

 

 

 

 

 

De : 'fasleitung3' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Envoyé : vendredi 1 décembre 2023 21:49
À : sara...@googlegroups.com
Objet : Re: [SARA] Yagi Patch 1420MHz NEC model ?

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[b alex pettit jr]

Hello Jim,

Very Nice !!

  " It is designed for low sidelobes and low temperature. "  Excellent !

>>>  Can you please provide Dimensions for building this ..

The feed appears to be weather protected ? 

Do  you happen to have an NEC Model of this ??

Best Regards,

Alex KK4VB

======================================================================================

On Monday, December 4, 2023 at 04:53:45 AM EST, jjm_...@wanadoo.fr <jjm_...@wanadoo.fr> wrote:

Hi Wolfgang, all

 

Yes this antenna works well for RA on 21cm. Thank you for this comment.

It is designed for low sidelobes and low temperature.

Here find 2 links as example of a small 21cm RT.

Observation of a meridian transits of our Galaxy and sun,  photo  (at home)

https://groups.io/g/radioastronomie-amateur/message/2108

 

with a small example of 1 image  (sorry, it it’s a French list ). Composite image with the Galaxy plan and sun transits On 24h.

https://groups.io/g/radioastronomie-amateur/message/2122

 

The transit was approximately at the +54° declination  (small circle UTC color coded )

o I am working to improve  the processing to catch better images and presentation of the data versus time (more integration time at 4min works also well).

[b alex pettit jr]

radioastron...@groups.io | Réalisation antenne 21 cm

radioastron...@groups.io | Réalisation antenne 21 cm

==============================================================================

Bonjour à tous,

Voici les résultats des tests de la disk Yagi 21 cm V6. La fabrication n'a pas posé de problème particulier, juste quelques variations de côtes par rapport à la version précédente, en pièce jointe vous avez les dimensions simulé par Michel. Les mesure du diagramme de rayonnement sont réalisé sur le stade de foot de Houeillès, mauvaise surprise, une cage de but est au milieu du terrain ce qui m'a obligé à modifier mon protocole de mesure, au lieu de me mettre dans l'axe du terrain j'ai positionné les antennes en diagonale sur la moitié du terrain. Les résultats de mesure sont dans le fichier joint. Les mesures sont conforme à la simulation sauf pour le rapport AV/AR. Il est fort possible que le mauvais résultat sur le rapport AV/AR soit lié à la configuration de la mesure, un pylône d'éclairage massif et métallique ce trouve dans la direction -188° il est donc fort possible qu'une partie du signal relevé dans cette direction soit un signal réfléchis par ce pylône. Pour lever le doute nous avons décider de réaliser des mesures complémentaires. Le détail de ces mesures analysé par Jean Jacques est dans le fichier joint.

Je tiens à remercier Michel et Jean Jacques pour leur contribution fondamentale à l'étude et la validation de cette antenne dédiée à la Radioastronomie. A vous maintenant de dire quelle suite donner à ce projet.

Bonne lecture,

Jean Marie F6ETU

=======================================================================================

  Translation   ( hopefully )

Hi all Here are the test results of the Yagi 21 cm V6 disk.

 The manufacturing did not pose any particular problem, just some variations of dimensions compared to the previous version, attached you have the dimensions simulated by Michel.

 The measurements of the radiation pattern are made on the football stadium of Houeillès, bad surprise, a goal cage is in the middle of the field which forced me to modify my measurement protocol, instead of putting myself in the axis of the field I positioned the antennas diagonally on half of the field. The measurement results are in the attached file.

 The measurements are as simulated except for the front/rear ratio. It is quite possible that the poor result on the front to rear ratio is related to the configuration of the measurement, a massive metal lighting pylon is located in the -188° direction, so it is quite possible that part of the signal recorded in this direction is a signal reflected by this tower.

 To remove any doubt, we have decided to carry out additional measures. 

The details of these measures analysed by Jean Jacques are in the attached file.

 I would like to thank Michel and Jean Jacques for their fundamental contribution to the study and validation of this antenna dedicated to Radio Astronomy. Now it's up to you to decide what to do next.

 Happy reading, Jean Marie F6ETU

Réalisation antenne 21 cm

Réalisation antenne 21 cm

Data Plotted

JJ F1EHN

================================================================

Alex

[b alex pettit jr]

JJ,

Has anyone tried adding the Yagi disks to a Patch Feed with Choke Ring to reduce Spillover ?

 1420MHz, LP

Alex

====================================================

[bsn...@gmail.com]

Thanks Alex and Jean Marie and all his associates.

A "disc log-periodic" Wonderful!

[b alex pettit jr]

Update :  an NEC Model

The Original Antenna is 2m long using 26 Directors

=======================================================

This version will be  1m long with 13 Directors

This model has 3500 segments and takes several hours to create a solution .. 

Next step will be to refine the reflector & patch,  and reduce the segmentation density on the director elements.

( Fn is quite close for a first attempt  )

Alex