Can I relocate the antennas on the C-8 hub with short coax extensions for better placement of the hub? I think it was said the connector is a SMA? If extension is ok would that use 50 ohm coax and what would the theoretical length be to maintain good performance? (5, 10 ft.) Look forward to using the new hub, on order, just doing some planning on hub re-location. Thanks for the help!
RP-SMA
Yes
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Just be sure you do some research, and buy decent cable. The difference between decent cable and poor cable in terms of a 10ft distance can be dramatic.
For example, 3dB of cable/insertion loss doesn't sound like much, but it means half your tx/rx power is lost.
S.
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Your loss of power would more than likely offset any gain. Each connection also losses gain. Height is your friend however. Raising it up with the stock antennas would probably give you better results.
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Consider moving the entire hub to a better location and/or using a higher gain antenna connected directly to the hub. A single USB power cable extension is much less expensive and simpler to route.
Its likely that putting the hub on the other side of drywall or even inside a wall will be lower loss than any length of cable plus an additional connector.
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Assuming the antennas are on the left side of the C8, which (ZigBee or ZWave) is toward the front and which is toward the back?
Z-Wave is closer to the USB-C port.
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These tend to be very lossy, unless you go with the REALLY good stuff.
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So this goes out of my experience a little bit, but anyone that has any experience I'd love feedback - would putting a 1m extension RP-SMA cable between the unit and the antenna bork my setup too much? Right now I have a C-7 that's in a 3d printed rackmount, and if I can move the antennas to the top of the rack I can keep my setup nice and clean. Thanks in advance for any insight!
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If its just for looks, i would surely not bother. As mentioned in earlier posts, every connection you make will reduce the signal strength. Using cheap cable and connectors will easily outdo the marginal improvement of location advantages.
In your case the 3d printed rack should not hamper the radio signals and if you can fit them as is, i would say thats a better alternative than putting the antennas on an extension. That is of course in terms of signal strength, not from the esthetic perspective.
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@robvogelsang These will work fine
I use these to mount to my rack but they could be adapted to anything
I tend to agree about just moving the hub to a better spot.
I used to play around with higher gain wireless antennas and more often than not, the longer cable for the antenna base killed any gain I was seeing.
Especially if you buy some cheap Amazon crap.
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Oh man I so don't want to get in a debate with an ambassador, but I used to design cell phones so I guess I have too.
Maybe its just poor impuse control on my part!
The very first amazon QA on this cable caimed 18db (6x) loss, another pegged it at "only" 5db loss.
They are probably both right since you can get an extra 10db loss from just a kink, pinch or because a nut is not as tight as it could be. RF cables are notoriously fragile because the internal dimensions are critical. The thiner the cable, the more finicky.
Loss isn't the only thing. The wavelength of 900MHz is about a foot and zigbee is much shorter so distructive reflections are a real thing in a 10inch cable, especially a small cross section one like this. This can really mess with signal quality (ISI) not just level.
HE was really smart to impliment a direct connect antenna with a hard, short 90. That means all the user has to do to get great results is make it tight.
The tiny C8 can be made flat enough to hang on a wall by installing the antennas sideways. It would fit behind a plate or picture.
It is probably quite easy to make the product perform worse than an internal patch antenna (C5/C7) by putting a cable in the way.
If a user is bound and determined to use a cable, I respectfully suggest first trying the C8 where the exrension antennas are going to be and collecting a baseline of performance.
Then install the cables and put the antenas and C8 where they are going to be. If it works, great! If not, you will know why.
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That's OK. It just means he speaks French.
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Honestly I believe you. I know enough to be dangerous in that arena. Have no problems deferring to someone who know way more than me. Anecdotally I'm using extensions (3') so I can clip the antennas to the top of my rack. I haven't experienced any I'll effects so far (though I don't have any equipment to measure the current wave lengths and strength)
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