Software Release: Skylark 5.0 for Dreamcatcher 3 (Ku-band)


#61

Do we think what @kenbarbi made is a simple noise shield, or is it actually a waveguide?

Hey Ken: Did you use any specific derived values for the cone, or was it just eyeballing something?

This instructions for this antenna provide way too much gain, but it can be chopped down pretty easily.

This document provides more DIY microwave antenna information than I have seen in any one location.

And here are a few pictures of some other homemade 12 GHz antennas.


#62

Just eyeballing - - and I had a shape I could wrap around. In was looking at the cone as a noise shield, but the wave guide idea is interesting. Ken


#63

If you pointed the cone-less antenna at the edge of reception–at a place you are getting -20 dB SNR, what impact does the cone have?


#64

Interesting question with unusual results. My edge of reception has an SNR of -14 dB with my lock coming and going. When I put the cone on the LNB at that point and aim it along the LNB’s direct axis to the sky, I get no change in SNR or Lock/Unlock status. But if I turn the cone in the direction of the satellite in the sky without moving the LNB, I get constant Lock and my SNR shoots up to - 9.5 to -10 dB.

I also got the same results today with the LNB pointed correctly. Without the cone, my SNRs were in -12 dB range with constant lock. With the cone over the LNB, pointing to the satellite, my SNRs went up to the -8.5 to - 9.5 dB range. What I did notice today (which I wasn’t looking for in my first test), was with correct LNB orientation, I could get the SNR to go into the -7.5 dB range by just sweeping the cone a bit in the general direction of the satellite.

Are we talking wave guide here, or still noise reduction? Ken


#65

possibly the only way to decide which happens if one put the LNB into a spectrum analyzer (powering up LNB via bias tee). Usually the interference is increasing noise floor which clearly can see on spectrum analyzer plot (eg.: rlt-sdr can do this possibly). Also if the interference is some discrete peaks that can identified too.

IMHO I bet the cone extension is simply increasing horn antenna apperture size so increasing gain. (On the other hand this means more narrow beam, decreased side beams which helps against interference signal reception…)

Quite hard to deiced, perhaps the spectrum analyzis can help. (rtl-sdr might work, if it doesnt have local self noise at that part of the spectrum, a priori good to check noise floor, without anything connected)


#66

Zoltan,
Here are some photos of my setup…

I found a particular spot where I can “see” SES-2 through the trees

My DreamCatcher is in a waterproof box with a LiPo battery in it. (Sorry the photo is sideways)

I’m almost done with getting my DreamCatcher powered over Ethernet. The TP-link Ethernet dongle works in place of the Wi-Fi dongle. I have some construction to do for running the Ethernet and coax through the plastic box and installing the PoE hardware. It should be up later during the week.

I will be ready to investigate antenna changes from there. I do have an SDR collection. I doubt that I would be able to see the Outernet Signal because it’s buried under the noise floor.

–Konrad, WA4OSH


#67

I doubt that I would be able to see the Outernet Signal because it’s buried under the noise floor.

Yeah, exactly… this makes the evaluation quite hard… With some luck maybe surrounding sat channels maybe stronger and can see just a bit above noise… But I’m not expect much stronger power on others, need to check.


removed this banner . It will no longer appear at the top of every page. #68

#69

Check SatSignature for SES-2. They have a large dish so they can see the signal clearly.

Unclick Show L-Band so that you see the Ku-band frequencies
Select Ku-Band
Select Vertical
Enter 11902.4 MHz in Frequency
Enter 5 MHz under span

…and you will see the live Outernet signal in Los Angeles.

–Konrad, WA4OSH


#70

Update on Aluminum Cone

With aluminum cone installed, I can now operate close to my house with a partially obstructed view of SES-2 thru the trees;

Good SNRs with signal lock and downloads occurring - -

garage -10

Two balloons over NYC - -

garage balloons

Ken


#71

@kenbarbi, how would we deal with water accumulation in the cone? Currently, we are receiving a lot of moisture, this would be a mess here. Our air quality is often poor, and we have a large accumulation of very fine sand dust in the air on a regular basis, so I’m wondering if there would be a way to put vent slots just above the attachment area to divest it, without affecting the operation.


#72

I think the idea of a wire mesh/chicken wire could solve for that issue. I’m curious about the performance of such a design.


#73

I’m not sure if it is a wave guide, as a microwave engineer would describe it. But it does seem to be creating a larger antenna aperture, so more antenna than just simple shield. I’m not even sure that a “shield” could even work in the way we are talking about.


#74

Thanks, @Syed. As time permits today, I may attempt this.


#75

Per the references in this link for mesh shielding see the "Shielding Effectiveness Graph pdf"
Link: https://www.twpinc.com/wire-mesh-material/copper/rfi-shielding-mesh

It claims around 20 db shielding for even the coarse 16 grid at 10 GHz.

So I conclude that a wire mesh (not chicken wire) would provide some shielding


#76

It’s really a circular feed horn. It needs a plastic radome.

20 or 32oz plastic drink cup, adhesive foil lined with a plastic lid.

I will talk to a few of my antenna engineer friends here in Seattle. They’re all doing $$$ phased arrays.

–Konrad, WA4OSH


#77

I’m going to try 2 things: 1) Wrapping aluminum duct tape around the LNB cover with little drip holes in it, and 2) A copper or aluminum window screen shaped like my cone. Ken


#78

Doing a screen here in Washington State will simply become a receptacle for squirrels hiding nuts, pine cones, moss growing inside, a nice bucket for ferns to start growing, wasp nests, humming bird nests, etc.

It’s going to be closed off with a radome here.

–Konrad, WA4OSH


#79

lol squrills love your things i see :slight_smile:


#80

Seattle’s nickname is the Emerald City because there are so many trees here. Trees come with all sorts of wildlife that enjoy a little basket to nest in, especially during spring :slight_smile:

–Konrad, WA4OSH