After a few more weeks of not getting on the air i managed to man handle the portable hexbeam up to about 4 above ground level note. It goes under the name of a myham hf7b and it is specified as an antenna with a useful range of 201715121064m bands. Im in the process of building a homebrew cobwebb ariel. Born in the cloud in 1996, cobwebs cloud services and solutions have empowered organisations of all size to grow into flexible, agile businesses through the deployment. Listed under the antennascobwebb category that is about cobwebb. After the success of my first cobweb antenna i decided to build a rigid version for my home qth, the design this time is based on one by g3txq. During recent range testing of a hexbeam i needed a horizontallypolarised resonant antenna covering 20m thru 10m which could be assembled and disassembled quickly and easily.
Purchase your mfj1835h 1500w cobwebb antenna at gigaparts today. A cobwebb homebrew build by dave 2e0ddhm0mbd loughton. I read about different results people got when changing the effective wire. All information, images, and documents on this website are the sole property of mfj enterprises, inc. The cobweb is a multiband hf aerial 20 through 10m of compact size and is almost omnidirectional. Mfj1835h 1500w 12wave, 5band hf cobweb antenna sku. Cobwebs, buy new and used products from ham radio, aerials. G3tpw cobwebb antenna for the 14, 18, 21, 24 and 28 mhz bands. This fiveband 20, 17, 15, 12, 10 meters halfwave openloop is perfect for restricted space or portable ope. If you are looking at this after speaking to me, you know it works. Cobweb is one of europes largest cloud solutions providers. Over the years i have experimented with quite a few wire antennas at home increasingly to minimise the effect of the increasing noise level from the likes of plasma tvs, switch mode power supplies, plt and adsl routers but fighting a losing battle on. The cobweb is the solution, great antenna for small places. The cobwebb is 5 separate full size dipole antennas, each bent into a square.
The actual field test, cobwebb antenna with the ft450 hf radio work well in blindspot, in addition to cobwebb antenna. We are using cookies to give you the best experience on our website. Cobweb diagrams with excel university of tennessee. I have a 200 ohm carbon resistor across the leads where you connect the antenna wires, then connect the core and shield of the 50 ohm coax to their respective wires. The cobweb antenna is a antenna which is easy and fast to install for portable operations, designed by g3tpw. This is a really versatile aerial for portable operating and is also quite simple to make its a 40m invertedv dipole but with the wires cut at certain points with crocodileclips soldered onto each piece of wire end. I noticed this in the latest practical wireless and thought id email a copy to mike corke, zs1rjq who has now made 6 of these. The antenna complimented my lowband horizontal dipole nicely and gave me the most useful hf bands 2010m without needing an atu. Note that this is the same as a standard dipole, although a straight dipole will have sharp nulls off each end. Being very pleased with the performance of the antenna and its convenience of use, the one downside for me, was the difficulty in transporting it, being approx 8. What this first test shows me is that the cobwebb is a very practical multiband antenna my end fed wires need to be changed to cover the 5 bands with a very acceptable performance. I am glad those of you who do have a working one get good results, in theory. The commercial cobwebb antenna marketed by steve webb g3tpw and most of the homemade derivitives overcome.
Hamshack sunday the vertical antenna and a qrp rig elecraft k1. Also in the cobwebb revealed pdf doc that i downloaded on page 5 it says each core is 42 strands of 0. The box at the feed point note that the crimp connectors are marked with the frequency, to avoid confusion. Mfj1838, 1500w, 406m, super heavy duty cobweb antenna mfj1838, 1500w, 406m, super heavy duty cobweb antenna 40, 20, 17, 15, 12, 10, and 6m built to survive the harsh northern wonters. Any reuse or redistribution of the contents of this website are strictly forbidden without authorization from mfj enterprises, inc. There was not enough time to find a pattern like distance or antenna used by the other side. G3tpw cobwebb antenna for 14, 18, 21, 24 and 28 mhz bands. Reading a lot of enthusiastic stories on the cobwebb antenna originally by stephen webb, hence the webb and considering its dimensions i thought it would make a good compromise for my situation. This hardware kit comprises a mast to boom clamp, a spreader clamp plate, central 1 inch diameter tubes, insulating fittings for the spreader arms and the necessary nuts and bolts pictured. Im in the final stages of putting a cobwebb antenna together id been umming and arring about putting a cobwebb together for some time. Listed under the antennas cobwebb category that is about cobwebb antenna projects. Here are my notes which should hopefully help anybody else heading down the same path.
The g3tpw cobwebb antenna covers five bands, 14 28 mhz, including the warc bands. This is quite easily the best antenna i have used, its small 8ft circumference omnidirectional and produces very little tvi. Thank you for purchasing the mfj1835 five band hf antenna. The antenna wires are pretty thin but that keeps the weight down i guess. Amateur radio communication equipment we sell amateur radio antennas, rf fitting plugs coax cable,mobile and home base, micrphones cb an ham radio m0zim. It is made by srw commuications ltd steve webb, astrid house, swinton, malton, n.
Transmitter power gets converted to rf, not to heating the ground, coax, or matching network components. Other useful information would include your experience with similar products, infomation on a product that you. The cobwebb is a five band 14 to 28mhz compact array of dipoles, bent into a square, almost omnidirectional and with unity gain. The cobwebb is a full size half wave dipole on each of the 5 amateur bands, 14, 18, 21, 24 and 28 mhz.
Mfj hf cobweb wire dipole antennas cover multiple bands and are suitable for many restricted space applications. It can be constructed from inexpensive materials and is mostly well. Cobwebb discussion, 4band cola antenna 20171510m, cobweb antenna construction details. I have a very small back garden and am limited with what type of antenna i can use. I do not think the pdf gives the element support dimensions very clearly. G3txq hexbeam, gm3vlb delta, g3tpw cobwebb, moxon, vk2abq etc.
Reading a lot of enthusiastic stories on the cobwebb antenna originally. Mfj1838, 1500w, 406m, super heavy duty cobweb antenna. Note the spelling of cobwebb vs cobweb the original g3tpw was designed by steve webb, hence the spelling. Over the past 15 or 20 years i have heard many good reports from users of the g3tpw cobwebb antenna. A checkup on my homebrew cobweb after the terrible storms recently, all seems well and still going strong after 3 years. The pdf shows the 17m element as 4400mm, i think this is a misprint, 4040 was intended. As ive stated before the cobweb antenna is fairly easy to build, im no great technical genius and yet i have managed to build both the g3tpw and g3txq antennas and if i can build this antenna, so can you. It is a very efficient horizontally polarised omnidirectional antenna for the 14, 18, 21, 24 and 28 mhz bands, with a gain of 7 db over an isotropic radiator 7dbi.
The cobweb antenna meets the requirement nicely it comprises 5 parallel dipoles bent into a square shape and mounted on a support structure made of fibreglass poles. Describe your experience with the mcr666 7 band cobweb antenna from 4 to 20 meters and tell us why you give it the rating you did required. Mr stephen cobwebb detailed pdf describing the cobwebb version. Cobwebb antenna projects category is a curation of web resources on, towertalk. We are both users of the cobwebb but both of us have homebrewed versions. The drawing below, is a basic sketch of the cobwebb design only 1 dipole shown what is a cobwebb antenna and what is its gain. Its multiband, omnidirectional and doesnt need to be located on a mahoosivetall mast to get decent performance. Cobweb diagrams with excel 12162004 5 at this point you can copy the formulas in the last two cells for x and the last two cells for y to as many of the following twobytwo blocks of cells as you like. The basic design is the similar to my portable version but this one uses a 1. Classic amateur radio g3txq cobweb antenna kd6rf blog. Loop dipole antenna, also published in the rsars elibrary, a. G3tpw cobwebb antenna for the 14, 18, 21, 24 and 28 mhz bands all the other small multiband commercial antennas that are available are less than. You can buy a complete cobwebb antenna, which can be purchased online from the web pages of steve webb g3tpw, the designer. The main advantages of the cobwebb over other 5 band 14 to 28.
The mmanagal view function figs 1416 show that the majority of the far field exists in the wire. I have found two different sizes for the twin cable elements, figure 8 42 strand 0. You can find out more about which cookies we are using or switch them off in settings. It is strongly made using fibre glass rods and comes pretuned, but is easily adjusted to ones own frequency of preferrence if required. Here is my setup for connecting to the mfj 259b analyzer that i have. Also, they are terminated into ring type crimp lugs, that are crimped and soldered. After a local amateur, keith g6nhu got himself a hexbeam i started to look at compact multiband hf aerials for the higher bands. Each of these twobytwo blocks of cells represents a step in the. My design is based on the wellknown cobwebb antenna using standard speaker cable, however only one gamma matched dipole will be constructed for 11 m band use.
1235 1092 1541 1112 481 550 518 222 1530 1188 1405 1525 1153 208 1627 1131 318 1333 374 433 1059 430 1525 1675 803 980 1421 969 906 1487 843 511 1282 55 125 131 316 855