Build your own "twig"

[rob12770]

sorry chris i read thru but I'm a bit unclear, what are you trying to do ? what receiver etc ?
are we talking ADS-B ?
cheers rob

 

[Archive-8]

sorry chris i read thru but I'm a bit unclear, what are you trying to do ? what receiver etc ?
are we talking ADS-B ?
cheers rob

Yes ads-b I know I need a good quality coax, and wondered about the RG213/U (mil-c-17f)

To make a new twig for 1090mghz.

I know I need a solid core. Found this and wondered if this would be a good choice.

 

[rob12770]

for actual construction of the antenna either 75 ohm or 50ohn is fine, what receiver are you using is it an RTL dongle did you say ?

 

[Archive-8]

for actual construction of the antenna either 75 ohm or 50ohn id fine, what receiver are you using is it an RTL dongle did you say ?

At the moment it's a cheapo Chinese dongle, waiting for my noo elec dongle with txco, filter etc.

But the other day me and a few of us were talking about co-linear for 1090 MHz.

E.g. The 8 segment co-linear I made last time was out of 0.30p a meter sat coax.

So I asked if a better grade of coax, to make the co-linear with, would yeald a better aerial.

And I was told I needed a solid core, found this, it has about 6 solid cores.

 

[rob12770]

if its solid core ( non bendy) then yes, otherwise you may have to put it in some plastic pipe as you need a vertically polarised antenna for Plane plotting, but yes that coax is fine, a Great site that might help you is here RTL-SDR Tutorial: Cheap ADS-B Aircraft RADAR - rtl-sdr.com

TBH chris i have bought more expensive dongles costing a bit more than yours and theres NOT much difference mate, noise floor maybe a LITTLE lower and a Tiny bit more sensitive but that's it
cheers rob

 

[rob12770]

its a funny thing Chris, ive built many antennas but always seem to go back to commercial store bought stuff, even if my homebrews work fine, maybe a lack of confidence I'm my own builds ?

 

[rob12770]

like the guys said, better if you can get it on the roof or poking out the loft skylight,

make sure theres nothing obscuring your antenna

 

[Archive4]

like the guys said, better if you can get it on the roof or poking out the loft skylight,

make sure theres nothing obscuring your antenna

View attachment 98356

That´s a nasty looking growth on the antenna!
Well, actually, he´s a good looking cat, so ask him to move nicely!

 

[Archive-8]

Made using the mil grade coax :-)



Looking forward to testing it out.

 

[rob12770]

looking good chris. the rtl sdr dongles have in impedance of 75 Ohms so sat cable will be fine to feed the antenna you made, however if you only have 50 ohm coax, its ok, as the mismatch would be minimal
cheers rob

 

[Archive-8]

At the moment the coax goes straight into the dongle. When the new one turns up, I will need some more coax to join them.

It took me about 5 hours to cut the coax/brade never come coax so tuff to work with.

Going to put the PC on now to have a look at the plot ranges.

 

[Topper]

All replies welcome !
Come on!

But would it fit up there?

 

[Archive4]

But would it fit up there?

The new one looks a little bendy, but who knows!

 

[Archive-8]

I have an ascars project on the go and want to make an aerial for it.

My question is would a full wave colinear be better than an 8th wave (with 8 segments)

Any help please?

 

[jeallen01]

The new one looks a little bendy, but who knows!

TBH, I've not used my 12-segment one recently (lots of other stuff going on) but I found that it was much easier to keep the segments straight and properly connected - especially when pushing them into conduit - if I carefully taped them to a thin bamboo cane. Then it was easy to slide the assembly into the conduit.

 

[Archive-8]

TBH, I've not used my 12-segment one recently (lots of other stuff going on) but I found that it was much easier to keep the segments straight and properly connected - especially when pushing them into conduit - if I carefully taped them to a thin bamboo cane. Then it was easy to slide the assembly into the conduit.

I will probably do the same.

I still don’t know what would be better a full wave, or an 8th wave (8segments)

 

[Archive-8]

My dump1090 aerial is not fairing well in the weather and is looking a little sorry for its self. When I ordered the wx aerial I also ordered one of the dump1090 aerials.

It’s turned up today



I now need to get the power socket sorted out. So I can test this one against my home made one.

 

[Archive-8]

The new 1090 aerial is working really well now I have a 175+ nm range apart from the north east of me. Terrain blocks some of that.



Vrs splat