Interesting 433MHz Mini PCB Fractal Antenna - Page 1
Forum section: electronics / projects

author: sparkswillfly
author_rank: Contributor
timestamp: November 08, 2013, 10:39:57 pm
content: Came across this. Anyone shed some light on this type of antenna and how to achieve similar designs?

author: Clint
author_rank: Regular Contributor
timestamp: November 08, 2013, 10:46:20 pm
content: It's a snowflake !

author: sparkswillfly
author_rank: Contributor
timestamp: November 08, 2013, 11:19:06 pm
content: True.https://en.wikipedia.org/wiki/Koch_snowflakeIt seems remarkably small for the frequency and features a filled design which is different from most examples.

author: sparkswillfly
author_rank: Contributor
timestamp: November 11, 2013, 11:19:09 pm
content: No antenna experts?

author: prenato
author_rank: Regular Contributor
timestamp: November 12, 2013, 12:48:03 am
content: No antenna expert myself, but this article seems to cover some of the design fundamentals:http://www.jpier.org/PIERC/pierc28/11.12022106.pdfPaulo

author: vk6zgo
author_rank: Super Contributor
timestamp: November 12, 2013, 04:12:48 am
content: There was quite a bit of discussion on QRZ.com about fractal antennas.The general consensus among the Antenna Gurus,was that they offered no significant improvement over more conventional designs.Theyarenice & "new age" though!

author: sparkswillfly
author_rank: Contributor
timestamp: November 12, 2013, 05:45:24 am
content: Well this is a commercial product so it must be reasonably effective. Most of the treatments I have seen on this type of antenna (including the link above) are targeting much higher frequencies. This is a small pcb antenna for 433MHz and if it has decent performance it seems impressive due to the size and cost.

author: ElectroIrradiator
author_rank: Frequent Contributor
timestamp: November 12, 2013, 07:25:59 am
content: Quote from: sparkswillfly on November 12, 2013, 05:45:24 amNo, it must not.Over the years there have been many attempts at 'shrinking' antennas without loss of efficiency, with little to show for it. The structures on the USB dongle are much too small to have any noticeable influence on the properties of the 'patch' as an antenna at 433MHz.Fractal antenna designs are used for making wideband antennas, not small ones compared to the wavelength.The antenna on the dongle is a simple, very short dipole using the main circuit as one pole, and with the blob as the other. There is no magic involved here. It is a inefficient as any similarly sized structure would be at this frequency.

author: ConKbot
author_rank: Super Contributor
timestamp: November 12, 2013, 01:19:01 pm
content: Quote from: ElectroIrradiator on November 12, 2013, 07:25:59 amThe meandering does drop the wavelength of the antenna a good bit (Ive shrunken a GPS patch from ~1.1" square to ~0.8" square on a ceramic patch and upped the bandwidth by a couple MHz with a dremel tool just mucking around ) But indeed, nothing magical as far as efficiency goes.

author: Lightages
author_rank: Unknown
timestamp: November 12, 2013, 02:23:14 pm
content: I was involved in a heated "discussion" on usenet a while back with a nutbar who tried to market his fractal designs and tired to show off in front of the HAMs on usenet. He made claims for performance he never backed up. It is all smoke and mirrors and as was said before never was proven to do anything other than look cool and maybe give a bit wider bandwidth.

author: hagster
author_rank: Frequent Contributor
timestamp: November 12, 2013, 10:16:30 pm
content: If you make an antenna smaller you reduce the aperture and hence efficiency. Nothing special about the fractalness of the antenna. It's just one way to add a meander to the line to make it longer. It's normally best to stick to more classical designs as they are much easier to predict and tweak. I'm sure a lot of these weird designs are just designed to get someone a patent. Also polarisation is often important. Who knows what it is for this antenna or that dremmeled RHCP GPS patch.

author: sparkswillfly
author_rank: Contributor
timestamp: November 14, 2013, 12:38:46 am
content: Aww man next you guys are going to tell me Santa Claus isn't real.

author: AlfBaz
author_rank: Super Contributor
timestamp: November 14, 2013, 12:05:14 pm
content: Quote from: mojo-chan on November 14, 2013, 11:22:12 amhmm...

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 14, 2013, 12:13:24 pm
content: Quote from: AlfBaz on November 14, 2013, 12:05:14 pmYour point being...?

author: AlfBaz
author_rank: Super Contributor
timestamp: November 14, 2013, 02:10:19 pm
content: Quote from: PA0PBZ on November 14, 2013, 12:13:24 pm...that reindeer are real

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 14, 2013, 02:19:45 pm
content: Quote from: AlfBaz on November 14, 2013, 02:10:19 pmYou're no fun

author: AlfBaz
author_rank: Super Contributor
timestamp: November 14, 2013, 02:28:26 pm
content: Quote from: PA0PBZ on November 14, 2013, 02:19:45 pmBetter?

author: prenato
author_rank: Regular Contributor
timestamp: November 14, 2013, 04:16:28 pm
content: Interesting thread. last year I watched this documentary on "Fractals" on public TV. One thing that intrigued me at the time was this part where they claimed fractal antenna design was a breakthrough in cell-phone antenna design, making them more efficient and much smaller than before. In-fact, ithe older cell phones seemed to have larger antennas, though not sure now if that's related. Are we saying that claim on the documentary was somewhat exaggerated, or even total BS? Just curious since antenna is really not my expertise, and I thought this fractal connection was a neat thing:) This would somewhat of a bummer if it not true...

author: mamalala
author_rank: Unknown
timestamp: November 14, 2013, 04:25:46 pm
content: Quote from: prenato on November 14, 2013, 04:16:28 pmBut then, at those times we had much, much less cell towers in operation. The smaller antennas in modern cellphones are only possible because the number of cellphone towers increased so much, resulting in a much denser net, requiring less transmit power on both ends to cover the shorter distances.If you could take a modern cellphone back to those times, you would have a hard time getting a good connection most of the time.Greetings,Chris

author: BBQ
author_rank: Regular Contributor
timestamp: November 14, 2013, 05:27:33 pm
content: Maybe it's an audiophile grade antenna?No crescendos lost in the aether.