Cobwebb antenna calculator download

This app does nothing more than the standard 468freq mhz type calculations. 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. Over the past 15 or 20 years i have heard many good reports from users of the g3tpw cobwebb antenna. The antenna is resonant on the bands it has been designed for, and to my delight i also find that it is resonant on 6m. Enter the function in the box, and choose an initial condition by dragging the point on the xaxis or typing a value in the textbox. I do not believe this is a loop antenna, but a folded. G3tpw cobwebb antenna for 14, 18, 21, 24 and 28 mhz bands. This link is listed in our web site directory since thursday feb 28 2008, and till today cobwebb revealed has been followed for a total of 12700 times.

Jan 18, 20 receiving new zeland station zl2jbr in madrid with cobwebb antenna in 20m band. The actual field test, cobwebb antenna with the ft450 hf radio work well in blindspot, in addition to cobwebb antenna does not require the land to build a complex network system, set up. Discussion in amateur radio news started by kj4yzi. It looked like just the ticket so i copied the design and low and behold after a few evening work i finished it off. Oct 22, 2012 last summer i built myself a cobwebb antenna and was fairly pleased with the results. Mfj hf cobweb wire dipole antennas cover multiple bands and are suitable for many restricted space applications. It is made by srw commuications ltd steve webb, astrid house, swinton, malton, n. 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. It can be constructed from inexpensive materials and is mostly well. We are both users of the cobwebb but both of us have homebrewed versions.

This fiveband 20, 17, 15, 12, 10 meters halfwave cobweb antenna is perfect for restricted space or portable operation. All information, images, and documents on this website are the sole property of mfj enterprises, inc. I have a very small back garden and am limited with what type of antenna i can use. This antenna covers 80 to 6 meters with low feed point impedance and will work with most radios, with or without an antenna tuner. Experiments with a homemade cobwebb type antenna posted on monday, july 8th, 20 by g4ddp 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 hf. About the cobwebb antenna the resource is currently listed in in 2 categories.

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. The main category is cobwebb antenna projects that is about cobwebb antenna projects. This applet performs cobwebbing for a firstorder difference equation. The cobweb is a multiband hf aerial 20 through 10m of compact size and is almost omnidirectional. Computer modelling of this arrangement shows that one result of bending the dipoles is that the antenna is close to being. Taylor, w2ozh, in which he described a low profile collinear coaxial array. Apr 09, 2017 there was not enough time to find a pattern like distance or antenna used by the other side. A useful microwave antenna calculator the antenna calculator is a very simple and easy piece of software. The dipole was 1db better broadside on but the cobwebb, being omni directional was 4db better than the dipole when the dipole was endon to the direction of the signal. Download hf dipole calculator 12 wave wire dipole antenna. The box at the feed point note that the crimp connectors are marked with the frequency, to avoid confusion. Radio amateur hf radio radios ham radio antenna satellite dish short waves tech toys retro futuristic intelligent design. A very basic program for calculating the length of each leg of a 12 wave wire dipole antenna. Its multiband, omnidirectional and doesnt need to be located on a mahoosivetall mast to get decent performance.

Join thousands of satisfied visitors who discovered amateur radio antenna, hf antenna antennas and mfj loop antenna. Classic amateur radio g3txq cobweb antenna kd6rf blog. A dipole or a cobweb has a gain of about 5db over a dipole in free space. Listed under the antennascobwebb category that is about cobwebb antenna projects.

I did think it was a bit heavy and was looking to repeat the build with some lighter weight wire until i came across this article from a wellknown antenna buff, g3txq. It is a very efficient horizontally polarised omnidirectional antenna for the 14, 18, 21, 24 and 28 mhz bands, with a. Any reuse or redistribution of the contents of this website are strictly forbidden without authorization from mfj enterprises, inc. The cobwebb is a five band 14 to 28mhz compact array of dipoles, bent into a square, almost omnidirectional and with unity gain. 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. Dec 29, 2012 regular contacts are made using this antenna with places like japan, australia, alaska, hawaii,south america, russia, italy and many, many more places using this particular design.

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. You can buy a complete cobwebb antenna, which can be purchased online from the web pages of steve webb g3tpw, the designer. About cobwebb revealed the resource is currently listed in in a single category. The cobwebb is a five band 14 to 28mhz you can buy a complete cobwebb antenna. Listed under the antennas cobwebb category that is about cobwebb antenna projects. Cobwebb spider antenna shortwave antennadiy production information ham antenna gift antenna manual chinaglobalmall. 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. This calculator provides quick estimation of antenna size. The antenna is designed to be fed with 50 or 75 ohm coax cable of most any length with a balun. Classic amateur radio g3txq cobweb antenna excellent technical reference article by steve g3txq.

Program good for 1 500 mhz, although intended for mf hf. The commercial cobwebb antenna marketed by steve webb g3tpw and most of the homemade derivitives overcome. Project cobwebb or cobweb antenna a diy guide build your own compact multiband hf antenna living in a densely populated area antennas are an issue here. Transmitter power gets converted to rf, not to heating the ground, coax, or matching network components. Winter is rolling in here to western nebraska now, and to my surprise, i was finally able to hear north and south dakota qsoing during the a. 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. W5gi mystery antenna the design of the mystery antenna was inspired by an article written by james e. Sep 07, 2016 i built a cobwebb 5band antenna for hf. Dipole antenna calculator software free download dipole.

If you are looking at this after speaking to me, you know it works. 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. The cobwebb is a full size half wave dipole on each of the 5 amateur bands, 14, 18, 21, 24 and 28 mhz. G3txq hexbeam, gm3vlb delta, g3tpw cobwebb, moxon, vk2abq etc. Click iterate to perform the next step in the cobwebbing. Here are my notes which should hopefully help anybody else heading down the same path. Experiments with a homemade cobwebb type antenna loughton. Receiving new zeland station zl2jbr in madrid with cobwebb antenna in 20m band. I built a portable version of a cobweb antenna, it is based on a design by stephen webb g3tpw and my adaptation of the idea is to make it so that it can be collapsed easily and when required reassembled and mounted hopefully on a telescopic pole.

It is strongly made using fibre glass rods and comes pretuned, but is easily adjusted to ones own frequency of preferrence if required. Other useful information would include your experience with similar products, infomation on a product that you would purchase instead of this one, and so on. A cobwebb homebrew build by dave 2e0ddhm0mbd loughton. 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. 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. This link is listed in our web site directory since thursday feb 28 2008, and till today the cobwebb antenna has been followed for a total of 4589 times. The table below shows the swr bandwidth with the antenna about 15ft high. A few years back i acquired a homebrew cobwebb antenna, which i used mainly for portable use with 40ft trailer mast. It goes under the name of a myham hf7b and it is specified as an antenna with a useful range of 201715121064m bands.

Whilst on the course for my foundation exam in february, i still had the words of john mulye g0veh ringing in my ears. Note that this is the same as a standard dipole, although a straight dipole will have sharp nulls off each end. Its a great dx antenna in a very small footprint package which covers 5 bands from 1020m without any need to use an antenna tuner. Hamshack sunday the vertical antenna and a qrp rig elecraft k1 duration. Well, here it is, a few months after throwing the antenna up on a 25 foot pushup mast and i am still happy with it. Im in the final stages of putting a cobwebb antenna together id been umming and arring about putting a cobwebb together for some time. The g3tpw cobwebb antenna covers five bands, 14 28 mhz, including the warc bands. Officially i can place one antenna provided it is situated at the back of my house and not higher than 5 meters above the point where the antenna or mast meets the roof line. The cobweb is fully omnidirectional so no need for expensive rotators. The cobwebb is 5 separate full size dipole antennas, each bent into a square. As the antenna dries out the normal tuning is restored. Note the spelling of cobwebb vs cobweb the original g3tpw was designed by steve webb, hence the spelling. Note peters plot of the dipole takes account of the effect of ground reflections which which fill in the theoretical nulls off the end of a dipole.

This hardware kit comprises a mast to boom clamp, a spreader clamp plate, central 1 inch diameter tubes, insulating fittings for the. As this is the g3txq variant, i refer to mine from now on as a cobweb. After a local amateur, keith g6nhu got himself a hexbeam i started to look at compact multiband hf aerials for the higher bands. However some of those really wet early snowstorms that caked the antenna really shifted the resonant frequency by over 500 khz on 20m and similar on other bands which basically rendered the antenna unusable until the sun came out and melted off the snow. Tags antenna, calculator, download, electronic software, rf post navigation. 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. The actual field test, cobwebb antenna with the ft450 hf radio work well in blindspot, in addition to cobwebb antenna does not require the land to. The antenna complimented my lowband horizontal dipole nicely and gave me the most useful hf bands 2010m without needing an atu. The basic design is the similar to my portable version but this one uses a 1.

As you will see its turned out quite well but you have to decide what mode you want as the antenna has not got a wide bandwidth. The measurements below are for building a simple dipole antenna. Regular contacts are made using this antenna with places like japan, australia, alaska, hawaii,south america, russia, italy and many, many more places using this particular design. Mfj hf cobweb wire dipole antennas mfj1835 free shipping.