Antenna thread

[Llew]

Yes of course, rocky up your way VS. Flat as my local's beer here, but still need to lift it clear of adjacent obstructions, makes all the difference.

 

[Vipersan]

Done a bit more ..
It occurred to be that I dont want to clamp low down at the 50 ohm connector end ...but indeed want the actual antenna (the white plastic 22mm tube) ...up in the air and clear of clamps ..
How to achieve this and retain stability ..
Then it came to be ..
2 shaped and cut down wrapover 22mm clip clamps place about 8 inches apart INSIDE a 40mm tube ...which is more rigid and easily clamped ...
The 22mm is then free to slide inside the 40mm tube ...until it hits the 22mm joint sections ...acting as end stops ..
This would also have the advantage that I could attach the 50 ohm cable first then extend the antenna to full height ..which would drag the cable up the iside of the 40mm ...providing both connectivity and an extra shield against the weather where the cable is connected ..

perhaps better explained in pix ..
so here they are..
scuse the untidy yard ..
Always is when I'm working..
lol

 

[Vipersan]

So ..now I need a wall stand off bracket approx 9 inches stand off to clear the gutter .....and able to clamp a 40mm plastic tube in 2 places..
I assume such a thing exists ?
Digi247 ..if you read this ..perhaps you could advise ?
rgds
VS

 

[Llew]

Done a bit more ..
It occurred to be that I dont want to clamp low down at the 50 ohm connector end ...but indeed want the actual antenna (the white plastic 22mm tube) ...up in the air and clear of clamps ..
How to achieve this and retain stability ..
Then it came to be ..
2 shaped and cut down wrapover 22mm clip clamps place about 8 inches apart INSIDE a 40mm tube ...which is more rigid and easily clamped ...
The 22mm is then free to slide inside the 40mm tube ...until it hits the 22mm joint sections ...acting as end stops ..
This would also have the advantage that I could attach the 50 ohm cable first then extend the antenna to full height ..which would drag the cable up the iside of the 40mm ...providing both connectivity and an extra shield against the weather where the cable is connected ..

perhaps better explained in pix ..
so here they are..
scuse the untidy yard ..
Always is when I'm working..
lolView attachment 93120

That's a nice solution to add some rigidity VS. I don't think mine will last the first strong winds up there, a bit too flexible maybe. The pipe is only fixed to the mast with click-on pipe clips. Maybe do something more permanent later, easy to access with a pair of steps atop the flat roof, dropped out through the bathroom window.

 

[Vipersan]

That's a nice solution to add some rigidity VS. I don't think mine will last the first strong winds up there, a bit too flexible maybe. The pipe is only fixed to the mast with click-on pipe clips. Maybe do something more permanent later, easy to access with a pair of steps atop the flat roof, dropped out through the bathroom window.

I don't doubt the actual white pipe antenna on mine will whip about a bit if the winds are strong enough ...but I'm hoping the extra rigidity of the 40mm pipe will help ...and in a storm situation with gale force winds I can theoretically slide the white pipe down inside the black and just push it up again after the winds have passed ..
It will mean getting ladders out of course ...and will only work this way IF I keep it at gutter height ..

If I move it to chimney stack ...all bets are off ...
lol

So ..this is the current collapseable height ..but could go further once mounted on a bracket..
This would obviously expose the bottom 50 ohm connector ..but would be do-able if needed..
;)

 

[Llew]

LNA arrived today (an LNA4ALL), so I hooked it in circuit - not the ideal place, the antenna, but 3 metres into the total 21 metre run.
A 10 minute check, with a minute swopover between LNA in and out gave me over a third extra aircraft ( 130 against 80 without the LNA).

Also, spectrum scan at 1090 MHz with and without the LNA, with a max hold over 2 minutes for highest peaks.

 

[Vipersan]

LNA arrived today (an LNA4ALL), so I hooked it in circuit - not the ideal place, the antenna, but 3 metres into the total 21 metre run.
A 10 minute check, with a minute swopover between LNA in and out gave me over a third extra aircraft ( 130 against 80 without the LNA).

Also, spectrum scan at 1090 MHz with and without the LNA, with a max hold over 2 minutes for highest peaks.


View attachment 93140

View attachment 93141

View attachment 93142

Nice job Llew ..
Which LNA did you order ?
Ideally of course the LNA should be as close as possible to the active elements of the antenna...which in itself presents a problem ..
ie powering the LNA..
Of course if the lna can take _pahantom_ power down the coax ...then you can inject your psu indoors using a bias Tee .....
rgds
VS

 

[Llew]

That's the LNA4ALL from adam alicajic, website LNA for all

18 EUR or 20 EUR with SMA connectors. I had them with SMAs, but didn't have any adaptors to fit F connectors, so I obtained some from Farnell ( SMA Male-F Male), while I wait for pigtails from China.

Yes, I will move the LNA up to the antenna eventually...

 

[Analoguesat]

Dunno if its of any interest to anyone but I noticed our B&Q had 22mm rigid white plastic plumbing pipe whilst I was in this afternoon. Individual length was about 2m. Cant remember the price but it was only a few quid.

 

[Vipersan]

Well after considerable reading yesterday and today ...it would appear the most suitable L band 1.5 ghz antenna to dish mount is the helical ...
So ...got some plans ..and made a start ..
Ordered a sheet of 4mm polycarbonate ..to manufacture a rigid X support for the helical element ..and a couple of sma female bulkhead connectors ..
I have already fashioned the helical element from 2mm copper wire ..and cut my reflector/backplate from powder coated steel ..
(was an old PC case side..)
Here is a pic of the 2 pieces already fashioned ...
Ignore the silver sticky tape ..
Twas just for the photo ..
rgds
VS..

 

[Vipersan]

Sun shining again ..so once again outdoors ..
This time to manufacture a blacket to mount the backplate on an offset dish ..
in this case a 60 cm offset ..
It may well me this isn't the best choice is part of the backplate will be masked ..but ya gotta try ..
lol
here are the pix

 

[Vipersan]

My lump of polycarbonate arrived about an hour ago ..
Cut into 2 slices and grooved for interlock ...
Amazing job by my motorized ceramic tile cutter ...
So ...made a start ..
gotta mark the support for drilling next then hopefully thread the element through it ..
that might get tricky but I have plenty of copper wire if I mess up ..
rgds
VS

..just got time to pop on my non EU regulation kettle for a 'quick' brew before I open the shop..
;)

 

[Channel Hopper]

Well after considerable reading yesterday and today ...it would appear the most suitable L band 1.5 ghz antenna to dish mount is the helical ...
So ...got some plans ..and made a start ..
Ordered a sheet of 4mm polycarbonate ..to manufacture a rigid X support for the helical element ..and a couple of sma female bulkhead connectors ..
I have already fashioned the helical element from 2mm copper wire ..and cut my reflector/backplate from powder coated steel ..
(was an old PC case side..)
Here is a pic of the 2 pieces already fashioned ...
Ignore the silver sticky tape ..
Twas just for the photo ..
rgds
VS..
View attachment 93293

I thought I had mentioned similar a couple of weeks ago.

 

[Vipersan]

I thought I had mentioned similar a couple of weeks ago.

You probably did CH ..
but following a recent email conversation with Adam C 9A4QV
designer of the LNA4ALL ...confirmation this was the best approach was confirmed..
rgds
VS

 

[hvdh]

A 60 cm dish for a 20 cm wavelength, challenging...
Please compare with results of the helical without the dish!

 

[Vipersan]

Will do Hans ..Only problem there is ..the polarity of course..

Here is the close to completion Helical Antenna ..
Certainly Pretty ..
If nothing else ...a piece of Art ???

 

[Llew]

The Turner Prize awaits...

Nice going VS, post your results when up and running.

 

[Vipersan]

The Turner Prize awaits...

Nice going VS, post your results when up and running.

..which sadly will be a day or so ...
waiting for some m2 nylon bolts to anchor the antenna to the backplate..
Sadly can't use metal bolts..
doh!

 

[hvdh]

Will do Hans ..Only problem there is ..the polarity of course..

Oh yes I forgot, the dish reverses circular polarisations.

 

[Channel Hopper]

Oh yes I forgot, the dish reverses circular polarisations.

Completely ignoring the permittivity of polycarbonate............

http://www.m-ep.co.jp/en/pdf/product/iupi_nova/physicality_05.pdf