Quote:
Originally Posted by MisterMe
What you don't seem to understand is that models of RF antennas have been tested in the Real World with the design, construction, and use of thousands of different antenna designs. The reason that models are more acceptable than controlled laboratory tests is that models have been proven to be more reliable than laboratory tests over decades. The models are based is Classical Electromagnetic Theory as represented by Maxwell's Equations. James Clerk Maxwell published A Dynamical Theory of the Electromagnetic Field in 1865. The great prediction of the theory was that electromagnetic fields propagated as waves through the vacuum at fixed speed. Here we are 147 years later and Maxwell's Classical Electromagnetic Theory works as well as it ever did.
|
Actually, I do understand a little of the background. Like I've said earlier, I do not have an engineering background, and honestly, most of the documents I've read are way over my head as far as the the math and the technical language used.
But for what I've noticed, its usually the non-technical person that is asking for help, and hit with terminology they can't or don't understand.
Again, I must stress that in my case, having just enough knowledge about antenna design to be dangerous <tongue in cheek> and trying a commercial product with a low profile (referring to my high wind conditions) that seemed to have very high rating, just didn't come close to what I built with scrap I had in my shed.
Aside from the technical aspects of design, the template (picture, not a modeling result) performed better.
So, with this in mind and considering my lack of higher education...
I was told (in a reply) that my version of the Ruckman design only had a 3dB gain. I'm also using 2 - 50 foot lengths of low quality RG 59 to attach my DIYantenna to my television. This same piece of RG59 has been used for more than 15 years, and at least 5 of those years outdoors. According to the chart at
http://www.universal-radio.com/catal.../coaxperf.html, I've got an expected cable loss of 7.6 dB or better. So, judging by the earlier reply, I've lost more signal strength than I've gained.
In order to use what simple equipment I have to measure signal strength (the signal strength meter on my television), I used the same low-end cable to compare both my DIY, HBU33 and the ClearStream2 antennas.
The ClearStream 2 (rated as having a gain of 10.2 Dbi) was installed outdoors, and approximately 6 feet higher that my larger DIY. At best, I could only receive 1 of the 2Edge stations, reading less than 30 on my television. Totally unviewable. My HBU33 at 9+ dB gain, could only receive the UHF 2Edge stations, but none of the HI VHF stations.
My DIY, mounted on a piece of foamboard with inconsistent bends, and far from perfect straight segments, and mounted on a camera tripod, receives all 4 of the 2Edge stations with a signal strength of 55 or better, and all of the LOS stations at 88 or better. BTW, I am not using any type of amplifier.
Also, keep in mind that the DIY is located at the northeast section of my house, and the 2Edge broadcasts are coming from the southwest. Not only does the signal have to go through the interior of my house, but there is enormous amount of EMF in the way. Cordless telephone with Bluetooth connection to my cell phone, kitchen appliances, electrical panel, WIFI in my living room and other WIFI computers directly in line with my DIY, more than 7 computers running 24/7, and directly in LOS of my DIY positioning, my radio internet antenna.
Please correct me if I'm wrong. In modeling, and in practice, both the HBU33 and the ClearStream 2 would be a much better choice for me, yet neither worked. However, my DIY, which seemed to have been abandoned by "the community", as referenced by Dave's first reply to my first post, out performs 2 of the accepted commercial available antennas. I also understand that the ClearStream 2 is advertised as a UHF, not a HI VHF/UHF antenna and actually a poor choice.
And yes, I do get interference when a plane is on approach to our airport, I'm very close to the airport approach airspace. But that would be expected with just about any OTA antenna. And yes again, reception does change with weather conditions, but I also understand that would be expected with a 2Edge signal.
In the responses to my original post, the theory and modeling behind my DIY shows it shouldn't work well. However, in application it blows the doors off the commercial recommendations. (Sorry for the analogy again.)
Either my inaccurate bending of the wire elements, especially with rounded bends vs. sharp points, or my inaccurate spacing due to not having perfectly straight pieces of wire to connect the 2 pair of elements changes the model, or maybe, just maybe, there really is something to be said about the true gain of the Ruckman Style Fractal design.