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External Antennas for Tungsten C Handhelds?
Scummer asks: "I am tinkering with the idea of replacing my old Palm Vx with a Tungsten C from Palm since I really like the WiFi capabilities of this new handheld. However, I have read in some reviews, that the range of the T|C is not that great since it doesn't include an external antenna. Has anyone tinkered with his T|C, and can tell if it is possible to place a connector for an external antenna somewhere in there? Is the internal antenna soldered or is it actually plugged, which would provide a better signal quality? I mean, browsing Slashdot and reading email on a T|C from the playground (which is about 1 mile away from my house [with a 15dbi external omni on the roof]), while my kids are having fun falling off the playground equipment, would be awesome." Solutions should try to be a little more novel than Pringles' cans and floppy disks but I don't think the submittor will complain if it works.
Palm devices, by their nature, move about quite a bit. This means that if you put a directional antenna directly on the device, you're going to have to learn to hold the device quite still. Not very practical. That leaves three choices:
1. Keep the isotropic antenna that's already in the device, and increase gain at the base station.
2. Void your warranty, open it up, and rig an external non-isotropic antenna (as suggested).
3. Use some kind of passive elements and/or reflectors to create gain.
For #1 above, the obvious solution is to point a directional antenna at the park. But if you want to have a signal at other places in the vicinity of your home, you'll either need to add more gain to your omni base antenna (15dB is a lot of gain already!), or adjust the beam tilt so the sweet spot hits the park. The drawback to either method is that you don't get something for nothing. Increased gain in one direction means negative gain (blind spots) in other directions.
For #2, the drawbacks are that you lose your warranty, and will have to keep the external antenna very still. You need to find a way to mount the external antenna in a fixed position, pointing at the base station. For example, you could use a clamp to fix it to a park bench, and rig something up to adjust it. I bought a $10 fan with a clamp and adjustments at Walgreen's that would do nicely.
Choice #3 is the most difficult to set up. You'll probably have to experiment a lot before you get results. Directional antennae use reflectors and directors in addition to the driven element to produce gain. You already have the driven element somewhere in the Palm. Depending on where it is, you can attach your own reflectors and/or directors to the outside of the Palm, and not void the warranty. It's more alchemy than science, but it can be done. I once taped a "T" antenna that comes with most FM radios to the ceiling, and then taped a few directors in the appropriate locations so that I could pull in a low-power college station. It wasn't pretty, but it worked! You're still going to have to contend with the problem of signal fading every time you move the palm, but it's worth a try.
Reflectors are used to get around obstructions. If you have a building between your base antenna and the park, you could put up a sheet of metal that essentially acts like a mirror to the radio signal. This probably isn't practical in your situation, but it's worth mentioning just in case. Moving the base antenna around could possibly align some existing metal structure to reflect in the right direction.
If you're not familiar with the various types of antennae, and the formulas used to construct them, I suggest going to your local library and checking out the latest ARRL Handbook.