Topics

3cm and 6cm dualband feed.


Chris G0WUS
 

Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal and linear polarization required.

Thanks in advance

73 Chris G0WUS


KENT BRITAIN
 

The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything.  Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







Chris G0WUS
 

Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?


On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything.  Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







KENT BRITAIN
 

The Vivaldi has a bit more gain and would work a bit better with that 
'flat' dish.   The LP would hold up better if you are mounting it out in the weather. 

While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon). 
The 2-11 of course gives you 13 cm.   And while no one has tested one to 
destruction, the Vivaldi will handle power better.   The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm.  The active area gets smaller and the heat is more concentrated 
as you go up in frequency. 

Hope I didn't muddy the water.   Kent

On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:


Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?


On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything.  Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







Chris G0WUS
 

Has anyone tried mounting the 2-11 LP in bit of pvc pipe to help keep the wx off?? Dish goes up for use and at most day or two before use and usually back down again after so would not be staying outside long term but bound to experience 4 seasons in one day.

Chris

On 06/10/2020 15:55, KENT BRITAIN wrote:
The Vivaldi has a bit more gain and would work a bit better with that 
'flat' dish.   The LP would hold up better if you are mounting it out in the weather. 

While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon). 
The 2-11 of course gives you 13 cm.   And while no one has tested one to 
destruction, the Vivaldi will handle power better.   The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm.  The active area gets smaller and the heat is more concentrated 
as you go up in frequency. 

Hope I didn't muddy the water.   Kent

On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:


Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?


On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything.  Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







Neil Smith G4DBN
 

If you use dielectric spike lensed horns, you can mount them one above the other and just nod the dish about 1.6 of degrees to flip bands. Even using a VE4MA on 6cm and a Pickett-Potter on 3cm, with a 1m dish, the required nod is only 4 degrees, and I couldn't see any different in sun noise between the 6cm at the correct focus and with it offset.

This is a dual-band setup I made for Tony G8DMU, very similar to mine, although it is inverted.  The 6cm horn is angled slightly shallower than the 3cm to ensure good illumination

Another approach with separate feeds would be like the 10/24 GHz feeds where the 10 GHz part acts as a dual-mode horn for 24 GHz. I guess that could be modified for 6/3cm.

Neil G4DBN
http://g4dbn.uk


On 06/10/2020 15:36, Chris G0WUS wrote:
Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal and linear polarization required.

Thanks in advance

73 Chris G0WUS


John Quarmby
 

Hi Chris

I use a feed horn based on the designs of G3PHO (for 3cm) and a dual band 6/3cm feed by WB5LUA published originally in the 1997 Central States VHF Conference Proceedings and reprinted in Volume 2 of the ARRL VHF/UHF Projects Manual.  See Backscatter P111 for details of the 10GHz version then just add the feed probe for 6cm in the wider part of the horn. Backscatter is available to download on the UKuG web site:

https://www.microwavers.org/backscatter.htm

Just be aware that there isn't much isolation from the 3cm to the 6cm feed, so your T/R switching needs to take that into account.

73

John G3XDY

On 06/10/2020 14:36, Chris G0WUS wrote:
Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal and linear polarization required.

Thanks in advance

73 Chris G0WUS




--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


KENT BRITAIN
 

One lad in the UK did put one inside a peanut butter jar.

I personally spray some clear paint on them, then mount about 10 deg off
horizontal.  Water tends to run to a tip and drip off.   Good for about 10 years
before UV destroys the epoxy in the fiberglass.

Thick plastic does change their tuning if the plastic is touching any of the Copper traces.

Kent

On Tuesday, October 6, 2020, 10:04:28 AM CDT, Chris G0WUS <sales@...> wrote:


Has anyone tried mounting the 2-11 LP in bit of pvc pipe to help keep the wx off?? Dish goes up for use and at most day or two before use and usually back down again after so would not be staying outside long term but bound to experience 4 seasons in one day.

Chris

On 06/10/2020 15:55, KENT BRITAIN wrote:
The Vivaldi has a bit more gain and would work a bit better with that 
'flat' dish.   The LP would hold up better if you are mounting it out in the weather. 

While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon). 
The 2-11 of course gives you 13 cm.   And while no one has tested one to 
destruction, the Vivaldi will handle power better.   The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm.  The active area gets smaller and the heat is more concentrated 
as you go up in frequency. 

Hope I didn't muddy the water.   Kent

On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:


Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?


On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything.  Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







Neil Smith G4DBN
 

Sunpat or Co-op peanut butter jars make good radomes. I cut holes in the lids and fit them behind the feed, then the body just screws on.  It is a bit subject to condensation, but I only use it for antenna-pattern tests and when out portable, so I can wipe it out and store it in the dry.

Sadly, my source of plastic jars has dried up as I now buy Yorkshire-made "Nowt but Nuts" peanut butter which comes in tinplate one-litre paint cans. Marvellous stuff.

Neil G4DBN

On 06/10/2020 16:10, KENT BRITAIN wrote:
One lad in the UK did put one inside a peanut butter jar.



SAM JEWELL
 

PA5DD had a picture on his web page of one mounted in a clear Polycarbonate drinks bottle.

73 de Sam, G4DDK




------ Original Message ------
From: "Chris G0WUS" <sales@...>
To: UKMicrowaves@groups.io
Sent: Tuesday, 6 Oct, 20 At 16:04
Subject: Re: [UKMicrowaves] 3cm and 6cm dualband feed.

Has anyone tried mounting the 2-11 LP in bit of pvc pipe to help keep the wx off?? Dish goes up for use and at most day or two before use and usually back down again after so would not be staying outside long term but bound to experience 4 seasons in one day.

Chris

On 06/10/2020 15:55, KENT BRITAIN wrote:
The Vivaldi has a bit more gain and would work a bit better with that
'flat' dish. The LP would hold up better if you are mounting it out in the weather.

While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon).
The 2-11 of course gives you 13 cm. And while no one has tested one to
destruction, the Vivaldi will handle power better. The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm. The active area gets smaller and the heat is more concentrated
as you go up in frequency.

Hope I didn't muddy the water. Kent

On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:


Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?


On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.

Not that I'm biased or anything. Kent WA5VJB/G8EMY

On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:


Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.

Thanks in advance

73 Chris G0WUS







John Quarmby
 

I use the end of a 2L polycarbonate drinks bottle as a radome for the 13/9cm feeds. Been up there 4yrs and still going strong.


73


John G3XDY

On 06/10/2020 15:24, SAM JEWELL via groups.io wrote:
PA5DD had a picture on his web page of one mounted in a clear Polycarbonate drinks bottle.

73 de Sam, G4DDK


------ Original Message ------ From: "Chris G0WUS" <sales@...> To: UKMicrowaves@groups.io Sent: Tuesday, 6 Oct, 20 At 16:04 Subject: Re: [UKMicrowaves] 3cm and 6cm dualband feed.

Has anyone tried mounting the 2-11 LP in bit of pvc pipe to help keep the wx off?? Dish goes up for use and at most day or two before use and usually back down again after so would not be staying outside long term but bound to experience 4 seasons in one day.

Chris

On 06/10/2020 15:55, KENT BRITAIN wrote:
The Vivaldi has a bit more gain and would work a bit better with that
'flat' dish. The LP would hold up better if you are mounting it out in the weather.
While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon).
The 2-11 of course gives you 13 cm. And while no one has tested one to
destruction, the Vivaldi will handle power better. The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm. The active area gets smaller and the heat is more concentrated
as you go up in frequency.
Hope I didn't muddy the water. Kent
On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:

Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?

On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.
Not that I'm biased or anything. Kent WA5VJB/G8EMY
On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:
Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.
Thanks in advance
73 Chris G0WUS

Virus-free. www.avast.com


Chris G0WUS
 

Hi John, thanks for the reminder on the Peter type feed that was on the build list some time back.

Being in the aquatic trade i always have grp projects on the go. I have done radomes for vhf/uhf ants before im assuming its still ok at shf?


73

Chris G0WUS



On 06/10/2020 16:52, John Quarmby via groups.io wrote:

I use the end of a 2L polycarbonate drinks bottle as a radome for the 13/9cm feeds. Been up there 4yrs and still going strong.


73


John G3XDY

On 06/10/2020 15:24, SAM JEWELL via groups.io wrote:
PA5DD had a picture on his web page of one mounted in a clear Polycarbonate drinks bottle.

73 de Sam, G4DDK


------ Original Message ------ From: "Chris G0WUS" <sales@...> To: UKMicrowaves@groups.io Sent: Tuesday, 6 Oct, 20 At 16:04 Subject: Re: [UKMicrowaves] 3cm and 6cm dualband feed.

Has anyone tried mounting the 2-11 LP in bit of pvc pipe to help keep the wx off?? Dish goes up for use and at most day or two before use and usually back down again after so would not be staying outside long term but bound to experience 4 seasons in one day.

Chris

On 06/10/2020 15:55, KENT BRITAIN wrote:
The Vivaldi has a bit more gain and would work a bit better with that
'flat' dish. The LP would hold up better if you are mounting it out in the weather.
While outside the spec, the 5-18 does have some gain a 3.4 GHz (use it soon).
The 2-11 of course gives you 13 cm. And while no one has tested one to
destruction, the Vivaldi will handle power better. The LP will take 40 watts at 9 cm.
and 10 watts at 3 cm. The active area gets smaller and the heat is more concentrated
as you go up in frequency.
Hope I didn't muddy the water. Kent
On Tuesday, October 6, 2020, 9:43:51 AM CDT, Chris G0WUS <sales@...> wrote:

Good timing Kent,

Just found your pcb logP 2-11ghz in the workshop drawer to. Would the Vivaldi work better do you think?

On 06/10/2020 15:41, KENT BRITAIN wrote:
The WA5VJB 5-18 GHz Vivaldi would work well there.
Not that I'm biased or anything. Kent WA5VJB/G8EMY
On Tuesday, October 6, 2020, 9:36:35 AM CDT, Chris G0WUS <sales@...> wrote:
Hi does anyone have any good ideas for a 3cm / 6cm feed to suit a sky
mini dish or maybe a 60cm offset dish?? 2 separate ports would be ideal
and linear polarization required.
Thanks in advance
73 Chris G0WUS

Virus-free. www.avast.com


Steve G4HTZ
 

Directive systems in good old USA do a dual band feed 

https://directivesystems.com/2304-mhz-above/6-cm-3-cm-5-7-ghz-and-10-ghz/

--
Steve G4HTZ 
JO01JN60
Great Wakering, Essex 
24ghz 1.8w 80cm dish 

also known to be active occasionally on 70cms DATV 


Stuart G1ZAR
 

DUAL BAND C&X band dish feed 6 & 3cm (5760 & 10368 MHz)
https://www.rfhamdesign.com/products/dish-feeds/multiband-dish-feed/index.php


Chris G0WUS
 

Hi Stuart, Is that any good for an offset tho or just PF dish??

Chris


On 07/10/2020 14:37, Stuart G1ZAR wrote:
DUAL BAND C&X band dish feed 6 & 3cm (5760 & 10368 MHz)
https://www.rfhamdesign.com/products/dish-feeds/multiband-dish-feed/index.php


Stuart G1ZAR
 

After further reading, PF only, Same can be said of the Directive Systems one as well.


Daniel DL3IAE
 

Hi Chris,

why not use 2 feeds, optimiised for your offset dish, next to each other?
I use the 10 GHz feed in the focus and the 5.7 Ghz Feed next to it, resulting in 7 deg offset for 6 cms.
The sacrifice is 1 dB max at 6cms. Pointing is easy as the opening angle will be double at half the frequency.
Have been using this system for 5 years with good results. See here:

https://s3.amazonaws.com/files.qrz.com/e/dl3iae/IMG_0794.JPG

The 5.7 feed can be found at the G4NNS website. Brian has designed a 10 GHz horn as well.

http://brcg4nns.org/FeedHorn.html

Good luck

73s
Daniel, DL3IAE


Daniel DL3IAE
 

... and if you switch both coaxial relays together, isolation is not a problem.
Requires just a single sequenzer.

Daniel


Alan Beard
 

Have you seen this, the Shorted Bow Tie?
https://core.ac.uk/download/pdf/70589636.pdf

Now, note the back plane, could it be a Corner Reflector?

As, I'm not short of "space" as in the medical use of this antenna type,
a 90 deg corner with the petals coming out at 60 deg ie. 15 deg off the sides.

Next, the balun. (Why?)

With thin coax, 1/8 in. hardline, come through the backplane and wrap it around the centreline
of the petal down to it's tip where the outer is soldered onto it's petal and the inner goes to the
tip of the other petal. 

Ah, these antenna gurus miss the obvious.

The feed impedance, this is a bit confusing, one article, around 30 ohms balanced feed, the other,  2x 50 ohms
with the petals modified wider rounded at the tip.

Any thoughts?

Alan VK2ZIW

On Wed, 07 Oct 2020 23:23:05 -0700, Daniel DL3IAE wrote
> ... and if you switch both coaxial relays together, isolation is not a problem.
> Requires just a single sequenzer.
>
> Daniel
> _._,_._,_


KENT BRITAIN
 

That is an Ultra Wideband Loop antenna.  Been around for quite some time.
Even that paper is 9 years old.

Note that the SWR is plotted in both frequency and Nano Seconds.

I'm not saying you cannot make it into a dish feed, but it would take a lot of work.
Reflector spacing that works for 6 cm would be a poor choice for 3 cm.
And we could get quite a discussion going on just where the phase center is.

Several simpler choices that are already 50 Ohm match over a broad range of
frequencies.        Kent WA5VJB/2E0VAA/G8EMY

On Friday, October 9, 2020, 4:12:54 PM CDT, Alan Beard <beardal@...> wrote:


Have you seen this, the Shorted Bow Tie?
https://core.ac.uk/download/pdf/70589636.pdf

Now, note the back plane, could it be a Corner Reflector?

As, I'm not short of "space" as in the medical use of this antenna type,
a 90 deg corner with the petals coming out at 60 deg ie. 15 deg off the sides.

Next, the balun. (Why?)

With thin coax, 1/8 in. hardline, come through the backplane and wrap it around the centreline
of the petal down to it's tip where the outer is soldered onto it's petal and the inner goes to the
tip of the other petal. 

Ah, these antenna gurus miss the obvious.

The feed impedance, this is a bit confusing, one article, around 30 ohms balanced feed, the other,  2x 50 ohms
with the petals modified wider rounded at the tip.

Any thoughts?

Alan VK2ZIW

On Wed, 07 Oct 2020 23:23:05 -0700, Daniel DL3IAE wrote
> ... and if you switch both coaxial relays together, isolation is not a problem.
> Requires just a single sequenzer.
>
> Daniel