For a current project I need a portable module (i.e., a Mote inside a portable case) and I'm trying to figure out the right antenna option to use. I'm worried that an antenna sticking out of the case will break off with moderate use of the device, so that means that the antenna assembly will need to fit in the enclosure. My options seem to be:
- Standard Moteino with the wire antenna wrapped in/around the inside of the case
- Standard Moteino with a helical antenna
- Moteino with the trace antenna option
This is my first RF project so I'm worried about getting it "right" (or, at least, not crippling the device with the wrong selection.) All other things being equal (location between nodes, power, etc.), what are the big difference between these antenna options that I should be aware of as I design the project & enclosures?
Thanks in advance.
Option 1 could alter the SWR and therefore power output. It'd also alter the radiation pattern and probably lower the range.
Sorry. Hit the wrong button and I'm on my phone.
Option 2 or 3 would probably be the best option. Downside of these choices over the quarter or halfwave dipole is most likely less range
Option 4 would be a ceramic chip antenna. They're small and decent gain. This, of course, assumes you're doing your own PCB.
I've had good success with Yageo (see Digikey).
@TomWS, I'm not looking to design my own PCB. I'm having enough challenges working with stock parts. ;)
@Kilo95, realizing there are probably a dozen variables (at least) that affect performance and wave propagation, would the trace antenna or the helical be a better bet? The units would be probably 50-100 feet apart between floors of a house.
Or is it a toss-up? I have 2 units, maybe I'll use one type in each and see how it works out?
handyguy,
It's hard to guesstimate how each antenna will perform since there are so many variables. I suggest just trying, in the order it makes sense (cost? compactness? ease of installation and use?).
Generally speaking, a bigger antenna will work better (ie bigger "speaker" can propagate "music" better than a tiny compact speaker, same everything else). In most cases the simple monopole will work absolutely great, if you can deal with it and not crumple it too badly in your project. Even in SwitchMotes, where they have to be wrapped around inside the case, they work across a large multi level typical american home, and in industrial settings. The helicals I offer in the store are also great compact performers.
Thanks, Felix. I'm still trying to design the final layout, it's good to know I have options.