So after celebrating a little bit and having Netbeans installed, I’ve decided to use Tim’s PHP code to give all my outlets a test. While I am doing that, I’ve decided to attach the antenna for the modules and thus began my studies on antennas and radio frequencies.
From my understanding so far, the controller dongle for RF Outlets uses a 12v power source. The signals being created are therefore stronger than the 5v signals coming out of the Pi. To solve that problem, my choices were to either increase the voltage or add an antenna. Increasing voltage from 5v to 12v is out of the question, the Pi needs some hardware upgrade to get 12v. Adding an antenna seems to be my only choice. Research indicates I’ll need the antenna to be 1/4 in length to the wavelength of the signals I am sending. The antenna ended up being extremely easy and I was over complicating things. In preparation for the antenna, I’ve reached out to several electronics guru whom I know personally or indirectly via friends. They gave me lots of answers and suggestions on how to solder an antenna to this IC. As for the antenna, it seems they all have the similar recommendations as the articles I read online.
The antenna is…
The Antenna is nothing more than a piece of wire. For this project, my Antenna is one of the wires from a patch cable. It is solid, thin, and easily obtainable.
I reached out to my friends at our service desk. My goal was to see if they have any garbage level patch cables that they need to be rid of. It would be difficult to justify buying a new patch cable just for one of its wires, economically and environmentally. The guys provided me with a broken one that was on its way to the landfill. The connector clip is broken on this cable and it would cause a disconnect if twisted a certain way.
Making and attaching the Antenna.
I cleaned the outer shell of the cable to disinfect it when I got home. To ensure I am not wasting resources, I quickly located the section of the wire where the damaged is. As it was 2 inches away from the broken clip, I simply cut it at that location. I still have about five and a half feet to work with on the good side and immediately took our my trusty ruler to measure the location for my next incision. As the optimal antenna length for the 315 MHz is 23.81 cm, I figured I will cut about 30 cm off of the patch cable, take one wire and shorten it after the it is attached.
In order to identify which connector on the transceiver is for the Antenna, I reached out to my gurus again. After consulting with them, they gave me several possible answers and I decided to reached out to the manufacturer for their response, hoping they would help. To my surprise, they did and their respond is the following.
This picture indicates the 433.92 MHz module, but the 315 MHz module have the same circuitry layouts. So what I did was stripped one end of the antenna and tied it into a small knot around the antenna connector, ensuring the metal surfaces touched. I am still not comfortable with soldering and since an old fashion twist works, might as well keep it that way for now.
Immediately, my signals were to able to reach further than it did without the antenna. The problem now is that it is able to reach down to the basement but not a particular corner with a bit more electronics. After testing it for a bit, I’ve shorten the antenna to approximately 24 cm and the signal quality improved to control 2 of the 3 sockets in that corner. I am sure if I go very carefully, cutting off 0.1 cm in iterations, I might be able to reach that last outlet also. However, at the current time, that last socket isn’t really something I would concern myself with as I have discovered that 3 of the 9 RF sockets running on 315 MHz would not respond to the Pi at all.