Greetings Ham'ers I have started to build a number of 10 to 15 minute tutorial videos on YouTube providing basic through to in-depth tuition in the use of many antenna modelling and creation packages. So far I am part way through a series of EZNEC videos and the first overviewing 4NEC2 was uploaded today. This will extend to a more comprehensive series with the use of Ansys HFSS including simulation of booms, insulators and coax included in the model which is of particular importance at VHF/UHF frequencies. I will extend these into design concept and principles videos and cover subjects such as 'What makes a Low Noise Yagi' and 'Do I need a Balun' which are just 2 of the most popular questions I have been asked over the years. I will also present several videos on percentage based element correction and why the more traditional fixed length correction (against boom size) will not replicate the 'wires only' model. Please stop by and take a look and if you like what you see, please do subscribe! https://www.youtube.com/channel/UC5IBDg7XIsZU5vTHkNfokUw Thank you! Justin G0KSC - ARRL Antenna Book Contributing Author www.g0ksc.co.uk www.innovantennas.com
when i think of modelling, it is usually plastic model cars, etc. i did 'model' a tv antenna from matchsticks for a friend's sister's dollhouse. it worked as well as the little plastic tv. i can probably learn something from these videos.
Very good and thank you . I've found that in many cases, modelling does not accurately reflect real-world capability and results. It certainly does have its place, but I still think that real-world experimenting is the best way to see if it really works.....
my thoughts on modelling usually involves women in skimpy lingerie showing off the newest antennas but I guess in ham radio it doesn't apply so you have to take what you can get.
Nicely done! I very much appreciate that the video lengths are kept reasonably short, the presentation is succinct, and they stick to only a few topics.
Hi Justin, That's great. Will have a look at it. Wondering how is the new HFSS doing?? Cheers. 73, Maximo
Actually antenna modelling is extremely accurate these days, especially if you setup the software correctly and of course use the correct software for the job in hand. The K1JT UHF (70cms) array I designed and built for Princeton (located on the science block) is illustrated in attached screen shot. Although the scaling's on the software prediction and the measured analyser results are different, you can compare one of the most the bottom red and pink lines (return loss/ SWR) on each. Slow lead in, double dip in the middle of the operating range and then a fast lead out. the top blue line on the left comparing with the bottom pink line on the right is perhaps the easiest A/B comparison to make . the bottom red line on the left (return loss)has more granularity allowing the double dip to be more easily seen. It is easy to just get an SWR dip where you want it but very difficult to get an antenna wrong and mirror-image predicted sweep shapes, especially when they are in the same frequency position on both predicted and measured. One you get to Ansys HFSS (future tutorials) all aspects of the antenna are accurately modelled, boom, coax, insulators, nuts and bolts etc. but this level of detail is really only needed once you get into complicated VHF arrays then UHF and up. The second image shows a low noise LFA UHF Yagi with through boom elements, insulators and a choke balun attached to the feed point within Ansys HFSS but at over $25,000.00 lease costs a year, this level of accuracy does not come cheap!
Anyone interested in antennas.. we have a Facebook page called. Amateur radio antennas large and small (all over the world).. feel free to post pictures of your antenna systems..
