Now on Google's Blogger

I have operated Linux web and mail servers since about 2000. For many years, I used a couple of 1U Dell server machines on a business DSL connection in Calgary. Eventually, I changed to a dedicated server in a data centre in Austin, in order to get better bandwidth, but the service wasn't really any better, it just cost more, so I changed back to a DSL setup for another few years. It worked remarkably well, and I had an uptime of more than 4 years, when a PSU eventually failed and brought the system down for a few days.

About 4 years ago, I got another one of the infamous middle of the night head hunter phone calls from the other side of the globe and I set off to the UAE. I then hastily moved my system to a data centre in Scottsdale. It worked fine till about 3 days ago, when it suddenly fell over and the data centre proved to be rather incompetent, so I hastily moved my service to Google.

So, now Aeronetworks is on Blogger and I'm trying to figure out how to hook the blog pages to my aeronetworks.ca domain name. I think I just have to be patient now, to let the DNS propagate. There is no way to rush a distributed system!

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Parasitic Quadrifilar Helical Antenna

This article was reprinted in OSCAR News, March 2018: http://www.amsat-uk.org If you want to receive Satellite Weather Pictures , then you need a decent antenna, otherwise you will receive more noise than picture. For polar orbit satellites, one needs an antenna with a mushroom shaped radiation pattern . It needs to have strong gain towards the horizon where the satellites are distant, less gain upwards where they are close and as little as possible downwards, which would be wasted and a source of noise. Most satellites are spin stabilized and therefore the antenna also needs circular polarization, otherwise the received signal will flutter as the antennas rotate through nulls. The helical antenna, first proposed by Kraus in 1948, is the natural solution to circular polarized satellite communications. It is a simple twisted wire - there seems to be nothing to it. Various papers have been published on helix antennas, so the operation is pretty well understood. Therefore,

Weather Satellite Turnstile Antennas for the 2 meter Band

NEC2, 2 m band, 146 MHz, Yagi Turnstile Simulation and Build This article describes a Turnstile Antenna for the 2 meter band, 146 MHz amateur satcom, 137 MHz NOAA and Russian Meteor weather satellites. Weather satellite reception is described here . A quadrifilar helical antenna is described here . Engineering, is the art of making what you need, from what you can get. Radiation Pattern of the Three Element Yagi-Uda Antenna Once one combine and cross two Yagis, the pattern becomes distinctly twisted. The right hand polarization actually becomes visible in the radiation pattern plot, which I found really cool. Radiation Pattern of Six Element Turnstile Antenna Only a true RF Geek can appreciate the twisted invisible inner beauty of a herring bone antenna... Six Element Turnstile Antenna Essentially, it is three crosses on a stick. The driven elements are broken in the middle at the drive points. The other elements can go straight throug

Patch Antenna Design with NEC2

The older free Numerical Electromagnetic Code version 2 (NEC2) from Lawrence Livermore Lab assumes an air dielectric. This makes it hard (but not impossible) for a radio amateur to experiment with Printed Circuit Board Patch antennas and micro strip lines. Air Spaced Patch Antenna Radiation Pattern You could use the free ASAP simulation program , which handles thin dielectrics, you could shell out a few hundred Dollars for a copy of NEC4 , You could buy GEMACS if you live in the USA, or you could add distributed capacitors to a NEC2 model with LD cards (hook up one capacitor in the middle of each element.), but that is far too much money/trouble for most. More information on driving an array antenna can be found here: https://www.aeronetworks.ca/2019/03/driving-quad-patch-array-antenna.htm l Air Dielectric Patch The obvious lazy solution is to accept the limitation and make an air dielectric patch antenna. An advantage of using air dielectric, is that the antenn

Aeronetworks sro - Airborne Linux

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