Ahhh you finished it! I remember when you were building your Cobweb... So.... how does it work?
Hi Steve,
Works great for a full sized HF antenna that`yet takes up the same physical space as an average TV antenna. I would like to point out the Cobwebb is 96% efficient compared to a dipole.
It is actually better than a dipole in many respects, because it is a true omnidirectional antenna without the nulls.
Let's examine the pattern here for a moment...
For the gentleman who requested information, here is a comparison between a half wave dipole and a cobweb. Both antennas are installed at 30ft over average ground.
Where this gets interesting when examining the plot in closer detail is the cobweb is never exhibiting less than a dB below the dipole, but yet is actually 10dB better than a fixed dipole over 60% of the azmiuth.
Cobweb highlights:
No antenna tuners required. Switches bands instantly and on the fly.
They take up far less space than a conventional dipole, but yet remain incredibly efficient. It's basically a full sized multiband HF antenna, inside a small 8 foot square footprint. Especially well suited for attics and HOA restricted communities.
As noted earlier, this particular antenna design maximizes radiation pattern characteristics and efficiency. In the pattern, you note there is actual gain achieved in many certain directions over a dipole without requiring a directional antenna or a rotor.
Folded dipole DC grounded design exhibits natural static buildup discharge capability and low receiver noise by design. This is a high Q resonate design exhibiting characteristics which eliminates wide band junk from other signal sources from other bands from getting into the receiver. The signals sounded much "cleaner" on the cobweb compared to a dipole.
Here's a video in a side by side comparison analysis.
Note ANT#1 (cobweb) vs. ANT#2 (dipole) on the top portion of the rig display.
Make yourself an 80 metre halfwave dipole fed with open wire to a 4:1 balun and you can have all the bands you need from 10-80, and you can use it as a sloper if you wish
What are the take-off-angles, i.e. the angle(s) of maximum gain, on the various bands?
You might be interested in the cobweb antenna article published by the IEEE.
Antenna radiation patterns are modelled in the different electric height, frequency of operation relationships and are specifically examined in this research article:
80 meter dipole not an option, no supports. I live on the prairie with basically no trees. Same reason NO LADDER LINE, the winds rips it apart. Last time I used ladder line the wind made it fail in 5 months. Thought about a loop, I am using a tuner at the base of the 22.5 foot vertical that would work fine on a loop. Just have to find places to tie it off to and that is the challenge.
Last time I used ladder line the wind made it fail in 5 months.
That could easily happen with solid conductors in the ladder-line. But have you tried The Wireman #554, "440 ohm, 14 AWG, 19 strand copper-clad steel"? That tough stuff has survived everything that Mother Nature has thrown at it here in Texas.
73, Cecil, www.w5dxp.com
Random length "tuned feeders" usually de-tune an antenna system (thus requiring a tuner).
After reading more about the cobwebb the narrow bandwidth is a no go, prefer something with wider 10m coverage. Haven't tried the wireman ladder line, will have to look into it. Thinking maybe fullwave loops for 10 and 15, I have enough roof space for that. Maybe delta loops on 17 and 12 off the roof peaks at 25 feet.
I have 4 31' telescoping wind sock poles they go down to 4' self storing I have 2 sets of them one set new. I have used 4 of them for Field Day the last 2 years putting up a full wave 80m loop coax fed using a couple of guys on each pole at corners. With an external tuner or I use a Elecraft KAT100 external for the K2 and the K3's with it's internal tuner to tune that antenna. The K3 will tune it from 6-80m and with my Palstar AT4k I can easly use it on 160m. Field Day it was used for QRP and logged 119 contacts operating part time from 10-80m only 2 on 80m though (summer) to be expected.
It is not up high enough but works and will go as high as your able to go and still give you a full wave loop for up to 80m. The loops seem be a quiter antenna than my vertical a Hy Gain Hy Tower AV-18HT with 72 radials. here at home I have a 160m full wave loop up also at 55' it works well.
If your intrested in my new spare set let me know and we will see what we can do. My email is good at my QRZ page.
73 de Fred N0AZZ
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