I too built a CoCo antenna. The plans that I used were from http://www.balarad.net. His instructions were fairly clear and made sense to me. I am using an 8 element antenna with each element 114 mm in length as described on the site. The coax cable that I used was RG6 quad shielded (this made pushing the core into the shielding quite a bit easier). There is a 75 ohm resistor on the top that I am using to bridge the shielding to the core. I am not using any of the transformers, lightning protection or amplification that he is using; it’s just simply the feed line to a F to SMA converter which goes to an MCX right to the RTL-SDR dongle. The feed line is no specific length or gaps or anything like that. I am not sure if that would have an effect on the reception.
Here is a pic of the antenna itself:
Now inside the PVC pipe:
Here is the set up in the attic:
You can see my other antenna in the back which is a 1/4 wave groundplane antenna. That antenna gave me max range out to about 160 nm but there were some blind spots for some reason. I didn’t really ‘tune’ this antenna, but with a bit of work, I might be able to see about the same performance as the CoCo antenna.
Over the stock antenna that came with the dongle, I more than doubled my coverage with the CoCo. The furthest range that I see at the moment is about 170 nm. The blind spots that I saw with the groundplane antenna are a bit more filled in.
See coverage over a 24 hour period:
My initial goal was to see over to the other coast and into Georgia, but now I want more. My next step is to build some lightning suppression and mount it outside on the back of my 2 storey house. I would love to be able to fill in some of the gaps to the southeast so that I can maybe see more flights out of Miami/Ft Lauderdale area.
Also, I want to thank user ‘paulmerkx’ for his write ups on his blog about tuning the antenna. Your work is definitely useful.