Free Supplies for Cone Extension Experiment


#1

I have four steel funnels that are manufactured by Behrens. I had been planning on some antenna testing, but I just don’t have the time. I’m happy to ship these to anyone who has the time to conduct and document a couple hour’s worth of backyard experiments. I don’t expect spectacular results from these funnels, as the angle of the funnels is twice what the actual horn is on the LNB, but there should be some improvement (60-degrees vs 30-degrees)

In addition to testing with both a naked LNB and one with the plastic case on, it would be interesting to see the SNR of all four sizes; so a total of 8 different data points. The best way to share this information is through a blog post, which we are happy to cross-post from our site. Here is what I can send (all free):

  1. four different funnels of varying sizes
  2. two LNBs; one to be tested with the case taken off
  3. Dreamcatcher for testing

I mapped this out as a Saturday afternoon project, so the goal would be to have the post ready to publish about a week after the package is received. The only requirement is that you need to be within the coverage area and have participated on the forum at some time in the past. If there are several interested parties, then we’ll let the forum members on this thread determine who should get the kit.


#2

If you have any extra funnels, I’ll participate - - I have DCs; naked and covered LNBs - - so don’t need those components. Ken


#3

@Syed
I am definitely interested!


#4

@kenbarbi and @maxboysdad It looks like it’s between the two of you. I only have one set of funnels to send. Could you let me know who I should send it to?


#5

Oh, I would defer to @kenbarbi, then, and look forward to his reports on progress.


#6

Ok it’s me. Thanks, Jerry. Ken


#7

I am interested.


#8

I’m working on Saturdays. Glad to help when I can.

–Konrad


#9

Thanks for the offers to help. The package was sent to @kenbarbi yesterday.


#10

I am always jumping between various setups that I have,
three separate coax runs each about 40 feet, feeding

  1. bare lnbf
  2. 90cm offset dish
  3. 18" offset dish

Sometimes the winds/rain move them around a bit…
but is there something I can enter into my setup’s so that the
5 minute status telemetry back to othernet headquarters can report
in the antenna config along with the other “tuner” parameters?

I normally have only one my dreamcatchers running skylark. The other
one is for “experiments”.


#11

Funnel Cone Test Results

I completed comparison tests of the Funnel Cones this afternoon at 1500 EDT 9 Aug 2018 on a clear sunny day in Annapolis, Maryland. I had to move further away from my normal antenna area to get the clearest view of the Southern sky. The results were the same whether I used a naked LNB or a plastic covered LNB. All the SNR readings represent the lowest reading during a 1 minute observation cycle conducted one after the other in a 7 minute period.

Bare LNB with no cone/wave guide over LNB SNR -10 dB Rssi -79 dBm
Collapsible Cup over LNB SNR - 7.75 dB Rssi -79 dBm
2x4x8 inch wave guide over LNB SNR -5.5dB Rssi -79 dBm
Largest funnel cone over LNB SNR -7.75 dB Rssi -79 dBm
1st size down funnel cone over LNB SNR -10 dB Rssi -79 dBm
2nd size down funnel cone over LNB SNR -11 dB Rssi -79 dBm
3rd size down funnel cone over LNB (the smallest) SNR -9.25 dB Rssi -79 dBm

All the funnel cones provide SNR improvements, but the best improvement is the original 2x4x8 inch wave guide

waveguide

I believe the martini shaker size (2x4x8 inches round) will match the wave guide in performance, and can be rendered in a collapsible fashion at a machine shop. I got the dimensions for the individual rings to be cut from 2 martini shakers so they all slip together. I need to find a machine shop that can do the job. Ken


#12

Could you share drawings and more detailed pictures of the DIY wave guide?


#13

Nice work, Ken!


#14

DIY Wave Guide
Made out of aluminum flashing from Home Depot or Lowes. I taped the 4 trapizoid sides together with duct tape.

Several folks made it out of garden chicken wire which is more wind proof.

chicken

Ken


#15

How did you come up with those dimensions?


#16

I took the martini shaker dimentions which I first tried and cut trapizoid paterns so I could piece it together in a foldable format for transport. I also looked at wave guide dimentions for 18 GHz sytems using wave guides which agreed with those dimensions and used them.

Not very scientific - - besides, I don’t drink martinis - - just wine :rofl:

Anyway, seriously, the specs of the martini shaker (2x4x8 inches) work well as Konrad’s antenna does and other’s are finding - -

Martini

@Konrad_Roeder will attest to that.

Ken


#17

@kenbarbi Your 4.5 dB improvement with the wave guide is much better than @Konrad_Roeder’s martini shaker. If you unmount the waveguide while connected to the LNB, how difficult is it to eyeball point?


#18

Knowing the general magnetic direction and elevation angle makes it easy to point by just looking for a spike in SNR from a -17 dB to a higher value around -14 dB. When I pass that point, I slow down my movement of the LNB to get a peak reading.

The one issue I have is that I mounted the touch screen on the front side of my portable terminal right under the LNB. Bad move, because to read the screen in sun light requires you to be head on to the screen which blocks the LNB with your head. Otherwise the glare prevents you from reading the SNRs.


(By the way in this picture I haven’t optimized pointing - - my elevation is too low and I am standing in front of the LNB to take the picture)

Ken


#19

I’m using a simple cone made from a paper cup and some aluminum foil and it works great.


#20

Ken did you have to add a ribbon cable to the display?