Radarspotting

Is there an easier homebrew than the one shown ?? if not, the coils do they twist slightly up or are they flat?

Thanks

Simon

Hi Simon

Which one "shown" where?

Sorry one shown in a post in this section of the forum http://www.tech-software.net/1090_ant_02.JPG (http://www.tech-software.net/1090_ant_02.JPG)

Hi Simon

no, there is nothing more simple to that proven design
Frankly you have to stick only with the coax-connector or your chioce,
the disc performing as a ground plane,
and the length of some copper wire.
There is only one turn each which may be twisted around some
and when the ends meet just later pulled apart a bit.
The exact distance between the two coils are not easy to hit,
some people had cut in between and soldered a piece between the coils.

All the rest is for fixing and weather proofing and may be any plastic material
(which has no hidden iron powder within, as some gutter pipe do)

Give it a try

Hi Klaus

Thanks for that i will have a go, but do you definitely need 50mm pipe would 32mm do or even 20mm

the thing that stumps me is the collars to wedge the 2 lengths of pipe to the disc of aluminium plate

Simon

Hi Simon. Have built two in the last couple of months. Only my opinion! they  pull in better then radar-100 Only concern is supporting them in 50 -60 mph winds.
But I will overcome it. Very easy to build

                                                                                  Regards
                                                                                   Billko

Quote from: yarmouthshipping on May 06, 2012, 05:42:34 PM

Thanks for that i will have a go, but do you definitely need 50mm pipe would 32mm do or even 20mm

the thing that stumps me is the collars to wedge the 2 lengths of pipe to the disc of aluminium plate

Simon

The dims for the cover are not at all critical, and as Billko put it the windload might be a factor to be considered.
32mm should certainly be ok provided you find a way of  getting/keeping the copper rod more or less in center
at least not touching the piping ( e.g. styrofoam wafers or such  )
BTW it must not be aluminum for the disc, copper might to heavy, tin can mat'l needs protection laquer
against corrosion.

Ok then i will have a go and see what happens thanks for all the advice

Here some background info
these measures are dependent of frequency respective wavelength
and here 1/4 WL or multiple thereof.
And that stand for those two single turn coils also.
The Dia of 20mm or ( ~ 22mm centre to centre multiplied by Pi  3.14 ) should represent
6.9 cm which again is 1/4 WL !

Myself found it is best to mark off the different portion of length,
continue with the sharp bends and finally form the single 20mm turns.
I had used 2mm iron welding rod for indoor attic use, maybe 3mm hard copper rod
is harder to bend.

Quote from: shakysen on May 06, 2012, 05:51:56 PM
Hi Simon. Have built two in the last couple of months. Only my opinion! they  pull in better then radar-100 Only concern is supporting them in 50 -60 mph winds.
But I will overcome it. Very easy to build

                                                                                  Regards
                                                                                   Billko

Where did you get the bits from i tried the usual subjects bq hb wilkes

they had pipe and thats it

Regards

Simon

Hi Simon. Have you any wire coathangers?. They work fine you may have to scrape off the coating to solder it to the socket. I have used wire of hangers for all kinds of antennas. and hairpin matches for my yagis. Another way is twin and earth take the solid earth wire and use that (30 amp)

                                                                                                             Billko

Sorry meant the pipe end caps and collars

Hi Simon I got mine from Koi center I use them on my filters .50mm £1.50 for end caps £2.50 mtr for pipe


                                                           Billko

No wonder i cant find the bits never mind

:-\

Hi again Simon.You have just solved the windage problem for me. Not going rooting around now.Tomorrow will do Ithink I have some thick walled pressure pipe 25 mm
and a25mm flange will let you know later if it works


                                                                                     Billko

got mine from screwfix 2mtrs for £1.47

Quote from: shakysen on May 07, 2012, 07:40:16 PM
Hi Simon. Have you any wire coathangers?. They work fine you may have to scrape off the coating to solder it to the socket. I have used wire of hangers for all kinds of antennas. and hairpin matches for my yagis. Another way is twin and earth take the solid earth wire and use that (30 amp)

                                                                                                             Billko

Hi all - a bit OT but it fits to homebrew !

re wire coathanger, I love 'em
these are my favourite dispensable travel items
good for vertical dipoles, GP , Triple(quadruple) legs,
all easily exact tailored to your freq

all you need are a few coathangers
one or two coax chassis-sockets of your choice (4-hole)
a plier for cutting and sharp bending
a length of customized coax cable
and that's about it.

everyone goes SMA, but for these purposes I prefer the Bayonet-Neill-Concelmann = BNC
no screwing here! Just quick connect/disconnect.

In practice I had some 3 cms of 1.5mm solid copper soldered into the chassis socket
and clamp the coat wire to it and cut to length. I do not know how you call it,
a metal clamp with 2 screws to connect two ends of wire e.g. Mains, or in switching boards.
A little bent hook ontop enables you
to hang it most everywhere e.g. hotelroom-window shades or what not.
Into the 4-holes you can hook  the lower section of a dipol.
with clever bending you can form radials to be horizontal as in GP, or drooping 45 degrees
downwards, holding indoors simply by gravity.
It works - the contact betwween the metal is good enough for VHF/UHF Comms .

almost forgot that;
Formula (short Version)
75/freq(Mhz)= 1/4 wavelength (meter)

have fun experimenting

Cheers Klaus

how did you get on i cant get any reception thru mine i have checked and checked think i will save for manufactured one

Hi Klaus.Take a look at this site (find one in english) http://f5ann.pagesperso-orange.fr/AntenneStrip-line1090MHz/index.html

                                                   Billko

Hi
tks, I had that french site previously bookmarked.
Have a look at AMOS-5
another and different approach this Franklin-centre feed type of antenna

BTW re etched PCB for antenna elements
one Juan Gelb of Brasile posted somewhere fotos
a/ of his homebrew collinear and
b/ a dismantled GP1090 this is also a slim PCB etched with 4 sections if I remember right.
sorry cant find the link anymore

Hi!!
Does someone know how to connect two 50 ohm antennas in one receiver and keep the 50 ohm?
My idea is put the demo antenna that's comes with microAdsb and my home brew high gain collinear antenna working together. 
Thanks.

Hi
well, when homebrewing at it, you could consider preparing a 1/4wavecoax-section as transformer.
with both antennas combined and such connected in parallel the resulting impedance is only 25 Ohms.
You can step this up by using a short length (quarterwavelength incl. velocity factor) of 100-Ohm Coax.
A bit tricky 1/4 WL = 6.88 cms , velocityfactor depending on cable 0.8 to .86 makes it only 5.5 to 5.9 cms length.

Formula
square root of (25 x 100) = 50 Ohms out.

So for practical reason use a T-Piece, center connected to Transforming section and
continue into your downleading coax cable.

so far the theory, question remains
are the different qualities of your antennas so prominent that the effort is justified
and not possibly spoiled by other factors ?

Hi Truetrack.

Thanks for your replay.

Let me try to explain what's happening.
A few weeks ago I built this project: http://www.wardrivingonline.com/equipment/antenna/omnicolliner-antenna-design.htm
I changed the length of 1/4 to 'feet' 1090 mHz.
The results are much better then demo antenna that's comes with microadsb but now I got a huge Doughnut affect.

Guto.

Yes that is plausible then.
All those multisectioned collinears whether industrially manufactured or homebrew
have these effect. They just focus the ring of lobe to the horizon, thus flattening it
like a doughnut.
One may use less elements resulting in less horizontal gain to a certain extent as a compromise,
and possibly use of expensive preamp and T-injection of power instead.

regards

Thanks Truetrack.

I will try to build the coax transformer using your formula. Right now buy an expensive preamp is out of context.

Let see what will happens!
Thanks again!

Guto.

You can make a pre-amp for about £4.

Take care how you feed in the power to it and make sure you provide a capacitor of maybe 100pf between the collector of the transistor and the input line to your receiver, else you won't do the RX any good at all.

Here is a really cheap one:

http://www.lll.lu/~edward/edward/adsb/preamp/ADSBpremap.html

Then you can buy this kit for about a tenner plus £2 postage:

http://www.g4ddk.com/SPFAMP.pdf

Here is another simple design:

http://users.belgacom.net/hamradio/schemas/preamp_HF_VHF_UHF_SHF_wideband_MAR6.htm

Quote from: Truetrack on May 06, 2012, 05:21:48 PM
no, there is nothing more simple to that proven design

http://www.tech-software.net/1090_ant_02.JPG

Are there any additional drawings or photographs of this simple 1090 MHz antenna?  I'd like to see the proper way to create the little 20 mm turns in the copper wire.  Are the turns mostly horizontal, or mostly vertical?

I see this additional drawing of the two caps butted together. 

http://www.tech-software.net/endcaps.bmp

Is it correct that the aluminum plate goes between the two caps?  Is the aluminum plate electrically attached to anything, such as the external connector on the Coax connector?

Also, the first drawing shows the lower tube section as 600mm.  Does the length of that section matter?  It seems the actual antenna is above that in the other section, and this tube only houses the coax you would connect to the antenna.  I have no problem creating that length - just curious as to why there is a stated size.


Thanks!

John

The member known as "shakysen" is your man. He knows how to make these.

Hi John. I use 20mm waste pipe,mark your bottom section with a bit of tape bend the wire Round the pipe.mark middle section and tape off same again with pipe. just pull each coil up so not touching. the vertical part must not touch the disk. They work very well 130-150nm, East,100-120nm North, 100nm South. An mine is poor in the West 90nm. Mine Are indoors

                                                                     Regards Shaky

Thanks Shaky!

I noodled around and also found the following useful information:

There are two sections at the page below discussing antennas, including a photo of his attempt at a ground plane antenna for ADS-B:

http://www.sprut.de/electronic/pic/projekte/adsb/adsb_en.html

I also found detailed instructions for a similar ground plane ADS-B antenna linked from here under "Your first ADSB Antenna":

http://www.atouk.com/wordpress/?page_id=237

John

Quote from: dongle on October 26, 2012, 04:40:07 PM
You can make a pre-amp for about £4.

Take care how you feed in the power to it and make sure you provide a capacitor of maybe 100pf between the collector of the transistor and the input line to your receiver, else you won't do the RX any good at all.

Here is a really cheap one:

http://www.lll.lu/~edward/edward/adsb/preamp/ADSBpremap.html

If anyone has had a go at making and using one of these can they please post the results, as in does it give a noticeable increase in range ? Thanks for any help.