Some experiences around the COBWEB
The CobWeb offers the following features :
- 20m, 17m, 15m, 12m, 10m operation
- Compact and easy to handle – Under 8ft square
- Doesn’t have to be too high – Reasonable performance at 10ft, with 20ft being the ideal
- Can be made with either figure-of-8 speaker wire (folded-dipole) or single-wires and 1:4 balun (for impedance matching)
- Can be constructed with PVC tube or fibreglass poles
- Possibility of being used portable if built right – perhaps with a tripod speaker stand?
Depending upon your circumstances, you may find this aerial visually more appealing that a 5-band flat-top fan dipole. The CobWeb can be a great /P aerial, too. A drive-over base and some swaged poles make a nice setup for operating from the car.
1) My COBWEB from EA Antenna
No general problem and easy to build even if the holes in fiberglass are not exactly in the same axe. I just drill more and all is perfect. The cross arm is very nice.
Problem on 15 m and 17m. The wires are too long. If I let the wire exactly in the holes in the plastic separators:
COBWEB at 4 meters from the ground for test
I tried it at just 4meters above the ground. In this configuration I get a better reception than with a Hustler 4BTV. So, not too bad.
I expect that at 10meters above the gound it will be better. If I substract 200khz I could get this:
On 21 and 24Mhz RS and XS are not so good.
|Bands||Minimal SWR at 4m||Imagine at 10meters above the ground with 200Khz substract||Results|
I added some wires on 18Mhz and 24Mhz. Around 2 cm. and all is perfect.
Very light and easy to raise on the roof with one hand. The antenna is at about 10meters above the ground on the top of the roof. No rotor, omni.. Great !
I get 1 or 2 points more than all the vertical antennas that are on the ground with radials. (4BTV, 12AVQ,…). My brother get the same results.
2) COBWEB from F1LAG (my brother in Normandie)
Alain decided to build his home Cobweb. Results are very good.