MFJ 5 Band Cobweb Antenna

[6meter]

Noticed that MFJ is now listing a CobWeb antenna.
http://www.mfjenterprises.com/Product.php?productid=MFJ-1835

In the past I've read over the websites of guys building the CobWeb antennas.
Here is one:
http://www.m0pzt.com/cobweb-aerial/

To me it seems like a cool concept to have a 5 band HF antenna that is really small and light weight. At something like 8 ft x 8 ft it could be a fairly stealthy antenna.

It's not a directional antenna so no need to rotate.

Certainly a dipole way up in a tree can probably offer better performance on a single band. But 5 bands on one coax run would be nice.

I'm interested in any reviews with information on SWR bandwidth for each band. For example how much bandwidth below 2:1 does it have for 15 meters?

The power handing capacity also as that could vary depending on how MFJ builds the matching section / balun.

I've thought about building a CobWeb to go with my HF vertical so will be interested to see how this one works out. Also the street price through other vendors like HRO.

 

[RatsoW8]

It's a relatively new antenna for MFJ so there are not a lot of reviews yet. The antenna is in itself one solution for hams who have very limited space to erect an antenna. If MFJ designed it like the original cobweb then the eHam reviews on G3TPW's version should help you.

http://www.eham.net/reviews/detail/1671

 

[w9cll]

hmm this looks interesting.

 

[M0GVZ]

I live 20 miles down the road from the original designer of the Cobwebb, Steve Webb G3TPW and I have an original one.

The SWR bandwidth below 2:1 is what you'd expect for a typical dipole, its low enough that you can get away without a tuner for most bands except 10m.

Performance is great, pretty much what you'd expect from a dipole without the directivity, and its what I used on 20-10m for all the contests I did from 2010-2013 and I have nearly a dozen first place certificates. 10m performance is poor though, most likely hampered by 12m but removing 12m would require the whole antenna to be retuned. A better solution for 10m for DXing is to just mount a CB vertical above the Cobwebb and retune for 10m.

Power handling for the original version which uses an ugly balun made from RG58 was OK at the UK legal limit of 400W which is only a S point down from the US legal limit of 1.5kW so not the end of the earth.

They're relatively simple to homebrew but the G3TXQ variant is far easier to tune. The shorting points of the twin lead in the original depend entirely on the diameters of the twin core cable and the insulation so unless you're using the same cable Steve Webb used, the measurements from the original are of no use. The G3TXQ variant uses single core cable and a 4:1 balun to raise the feedpoint impedance from 12 Ohms to 48 Ohms.

http://www.karinya.net/g3txq/cobweb/

 

[6meter]

The SWR bandwidth below 2:1 is what you'd expect for a typical dipole, its low enough that you can get away without a tuner for most bands except 10m.

Power handling for the original version which uses an ugly balun made from RG58 was OK at the UK legal limit of 400W which is only a S point down from the US legal limit of 1.5kW so not the end of the earth.

They're relatively simple to homebrew but the G3TXQ variant is far easier to tune. . The G3TXQ variant uses single core cable and a 4:1 balun to raise the feedpoint impedance from 12 Ohms to 48 Ohms.

http://www.karinya.net/g3txq/cobweb/

Thanks for the feedback. Every antenna has a degree of compromise. But the bandwidth sounds pretty good. For a light weight / low visibility antenna it seems promising. When researching the CobWeb last year it was apparent with the smaller size yards / "gardens" in England that the small size was part of its appeal. With the prevalence of HOA's and restrictions in the US I would think the CobWeb could become popular here.

With 600 to 800 watt amps being fairly common, hopefully the MFJ will be built to handle that.

The G3TXQ version was what I was looking at as the single conductor wire seems like a much easier build.

 

[M0GVZ]

With 600 to 800 watt amps being fairly common, hopefully the MFJ will be built to handle that.

The alternative is that people figure how little difference the extra 200/400W will make over the original design limit and just run their amps with less power.

The rest of the antenna other than the ugly balun is more than capable of handling several hundred watts, its just the use of RG58 that hampers it.