[TriEmbed] Di-Pole Dilemma

[Charles McClelland]

To all,

I am playing with the Moteino and recently tested the range at a local park.  I was a bit disappointed and discussed this at the last meeting.  As with all things embedded, there seems to be a number of things that can be done to improve performance both hardware and software.  For this note, I wanted to ask for any advice on the hardware front.  Once I have that set, I plan to tweak the software settings (primarily data rate but some others as well) to see how much range I can get - ideally 1.5 miles outdoors through wooded terrain.

The Environment:
	- Moteino base and sensor nodes 
	- I went with the lowest frequency transmitter - 433MHz - and the highest power
	- The Moteino site states that there is not much improvement from monopole antennas   
	- In the forums however, there is a posting promising greater range from dipole antennas

I understand that a directional antenna would be better but my application would not easily support this as the sensors nodes may need to be moved frequently.

My limited understanding of a dipole antenna theory is that there are two elements - one with signal and one with ground with each sized to match the specific frequency.  I plan to add an SMA connector to the board so I can install a commercial antenna and I found two options that both claim to be sized to the 433MHz frequency:
	- The first looks like what I expected a dipole antenna to look like and could be easily made
	- The second would be much better for packaging and use on a sensor that may be moved often - but it does not look like a dipole antenna to me.

Any advice on which might be the better choice or whether I should look at other options?

Thanks,

Chip

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