Smallest EMWIN antenna

[sammyizimmy]

I am trying to build a standalone EMWIN weather station. I have a rtl-sdr for the receiver but I know virtually nothing about L-band antenna building. I want the smallest antenna design for this. Is there any way I can get away from a dish? Should I use a (yagi, helix, patch) antenna? Once I have a signal to my receiver I am good from there. I am new to this so if anyone would have some good tips or link I would appreciate it.

Thanks

 

[KE4EST]

You can use a yagi.....collinear array. It will still get kinda large, if you want any real gain. You will need at least 4 yagis for a good signal properly co-phased together. More is often used.

 

[sammyizimmy]

For the yagi, does this look like a good article to start with?
www.sciencepubco.com/index.php/ijet/article/download/234/208

But the collinear array? never heard of that, I'm still googling and trying to wrap my head around that concept.

 

[KE4EST]

Wait a minute I jumped the gun. I thought you wanted to receive EME signals.
So don't worry emwin will not require a massive antenna.

 

[sammyizimmy]

Nice! Although I think EMWIN is circularly polarized...
According to this (http://sv1bsx.50webs.com/antenna-pol/polarization.html) I should use a Helical or X Yagi.
Helical vs X Yagi, is one better than the other? what are the pros and cons of them?

 

[FaT Air]

Looks like all the other yagi DIY instructions I've seen. BUT I'd also use a 1:1 Balun at the feedpoint AND
On their page it states: "The EMWIN data stream is also currently uplinked to the Telstar 5 (now named Galaxy 19) Satellite, located at 97 degrees West. The center frequency of the Telstar 5 EMWIN signal is 12,185 MHz, subcarrier frequency is 1.065 MHz. "
So a Ku LNB(F) with suitable power insertion on a 1 meter dish would be suitable. (tune to L band I.F. of the LNB(F) at 1435Mhz)
They don't mention the polarity??? That would be a much smaller 'footprint' on the landscape. Or is this outdated info???
Funny thing is I can find no mention of the polarization employed for it on the GOES satellites. But back in the Gemini Space craft. days they used pretty near the same freqs and it was all circular polarized. And would require a helical antenna. (tracking/comm site was near here with many helix arrays)

colllinear: http://en.wikipedia.org/wiki/Collinear_antenna_array

 

[sammyizimmy]

"They don't mention the polarity???"
I'm glad you challenged me on that, looks like I had the GOES ReBroadcast (GBR) in mind not EMWIN.

EMWIN currently is QPSK(and will change to BPSK 2017?)

Source(http://cimss.ssec.wisc.edu/goes_r/meetings/guc2009/presentations_final/1104_0945_Reynolds.ppt)

 

[FaT Air]

GOES ReBroadcast is VHF and if there's a station near you a ground plane or yagi or a coaxial collinear should be all you need.
Only trouble is you'd have to up convert to a freq the SDR can tune.

 

[Kraven]

Is there an actual benefit to having your own weather station? Besides the technical challenge that I'd enjoy, I dont see
much point to it considering we all have the weather channel

 

[sammyizimmy]

Is there an actual benefit to having your own weather station? Besides the technical challenge that I'd enjoy, I dont see much point to it considering we all have the weather channel

The location that I would like to install it has no internet or TV. also the "one time cost" appeals to me(but not nearly as much as the technical challenge)
Currently this is sorta what I am thinking
GEOS East -> my antenna -> SDR -> raspberry pi with small touch screen
It's the GEOS East -> SDR that I'm a bit lost, from there I feel pretty cofident that I could handle it(I do c++ and java)

 

[sammyizimmy]

Looks like a 1m dish with a cantenna might also work....

 

[Joe DC]

Do you have access to NWS VHF (i62.4 -162.55 ish)weather announcements? Might require less of an antenna. Can be received by SDR also.

 

[sammyizimmy]

Do you have access to NWS VHF (i62.4 -162.55 ish)weather announcements? Might require less of an antenna. Can be received by SDR also.

I do but having radar and GOES images is a big selling point.

Found this looks pretty interesting (http://www.satfix.net/showthread.php?45971-GOES-11-and-EMWIN-L-Band-signal)

 

[Titanium]

Looks like a 1m dish with a cantenna might also work....

Why a cantenna? Use a 1M dish and regular LNBF with a 18Vdc power inserter. G19 - 12185 is a horizontal transponder, so it is likely that 12184 SCPC is horizontal as well? There is no circular polarization on Galaxy 19.

If you want to run everything on battery, use a 12Vdc battery to power the LNBF with a voltage blocker inline to protect the SDR. Rotate the skew 90 degrees out of normal to receiver horizontal (as only the vertical element will be active).

No need to reinvent the wheel... unless you want to!

 

[sammyizimmy]

Hm. Maybe I am missing something but doesn't this(http://www.nws.noaa.gov/emwin/winsat.htm) say "the GOES downlink frequency for the EMWIN datastream is 1692.7 MHz". Can a Ku LNB(F) receive this?
I don't think the Telstar 5 is still transmitting EMWIN(Correct me if I'm wrong). I am trying to contact NOAA to confirm this.

 

[Joe DC]

Many years ago I built a 4' dish out of metal window screen and aluminum frame/ribs with a homemade LNA. This combined with a police scanner as a receiver and a converter to the computer did a good job of receiving GOES images. The dish was even used in the house. The dish probably had a gain of about 24 dBi. If you wanted to use a Yagi type antenna instead it would need to be very long (approx 14') for the same gain. There are several online sources to help design a long yagi.

 

[FaT Air]

"the GOES downlink frequency for the EMWIN datastream is 1692.7 MHz". Can a Ku LNB(F) receive this?

No. That's in the band that the Ku LNB outputs. 11700 to 12200 Mhz IN. OUT 950 to 2400 Mhz. A FTA STB or SDR could receive the signal with just a Low Noise Amplifier used - no conversion necessary.

 

[sammyizimmy]

No. That's in the band that the Ku LNB outputs. 11700 to 12200 Mhz IN. OUT 950 to 2400 Mhz. A FTA STB or SDR could receive the signal with just a Low Noise Amplifier used - no conversion necessary.

Would the Winegard-LNA-100 work? I can't seem to find any real spec. The price is nice!

 

[FaT Air]

No. the highest OTA television frequency is 698 Mhz. (ch-51) or 890 if ch 83 was still available.
If you can get the SDR really close to the antenna, might not need an amp. But ????? no idea really if that would work. All depends on the sensitivity of the SDR. From what I've seen, they aren't that sensitive. LNA's at 'bay

 

[sammyizimmy]

Has anyone had any experience using the MAX2659 (http://www.mouser.com/ds/2/256/MAX2659-74449.pdf) as a LNA?

How can I figure out what value C1 and L1 i would need for 1692.7Mhz (I am guessing they have it optimized for 1.5Ghz)?