Improving range

[galinette]

Hi,

I have a bunch of Oregon temperature sensors, inside and outside, over two floors, as well as Chacon door contact sensors on windows. I have switched to a high gain antenna, and optimized its placement by a lot of thinking from the home 3D sketchup map (looking at the walls crossed, etc...), taking orientation into account, and by a lot of trial and error. Things improved a lot, but there are still times where I loose some sensors for a couple of hours, before they reappear.

I know I could add a second receiver forwarded over ser2net, but I'd like to try any other possible solution before doing it.

1) Is it a good idea to add a second antenna on a single transceiver, by using a SMA tee? I'd say it's a bad idea, since in some case both antennas will in phase opposition and cancel each other signal. But who knows, maybe I can have interesting results by orienting them perpendicular, so that I have more angle coverage.

2) I have only a few sensors which are problematic. Is there a significant improvement possible by changing the antenna on Oregon temperature sensor? For instance by adding a SMA connector and an external antenna.

Thanks!

[Dave21w]

You cannot just add a second antenna with an sma T and expect it to work, without proper calculation of feeder (coax) lengths the matching impedance of the tranceiver to the antenna will be miles out and reception and transmission will be far worse than a single antenna.

If you really want to experiment with dual antenna's you need to look up information on a "phasing harness" for the frequency in question which is 433Mhz, as this is part of the amateur band it's usually refered to as 70cm (thats the full wavelength) so search for 70cm phasing harness and you will get lots of hits for calculations etc.

One thing you need to think about is that all these temp sensors transmit their readings at intervals of usually a couple of minutes, this timing isn't exact so there will be occasions where 2 devices are trying to talk at the same time, this will either cause the signal from the weaker one to be ignored as it can't be heard or it will cause data corruption for both so neither one will update, the chances are any antenna improvement won't remedy this problem as the stronger signal will be even more so and the weaker one will still get flattened.

It is quite possible that the sensors you lose for a couple of hours have very close update patterns and periodically they cross over and it's not till they are far enough out of sync again that they reappear.

Hope the above helps (at least a little)

Dave