The RTN-16 has 3 Antennas yet Tomato only allows you to choose 2 of them when selecting the Transmit/Receive Antenna, does that mean that one of them is going to waste?
Date: 10 Dec 2010 15:26
Number of posts: 8
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My thoughts and questions too….
I wall-mounted the RT-N16 on its side and am having trouble setting the antennas vertically since the UTP cables are in the way. I am planning on installing a multibase so I can mount one of the antenna elsewhere but cannot seem to find any reference anywhere which of the three to use.
Rob, - no, your antennas are all used - see below. The choice of antenna in Tomato related mainly to the older, non MIMO, use of the radios.
ntginson, - you don't have to mount MIMO antennas vertically, just remember that the path radio waves take to the antennas must be different no matter how you mount them. Don't worry about it.
There doesn't seem to be much information on the web about MIMO that the guy in the street would understand, so here's a very simple description of how it works.
To make it possible to use higher speeds, you might imagine that you use two routers at once. That, for instance, could double the throughput. Now imagine that a router has two transmitters and receivers in one box. Again, this could be seen as doubling the throughput. But both of these ideas would of course accomplish this by taking up two radio channels.
What MIMO does can be considered as having those two radios on the SAME channel and both transmitting at once - each transmitting different information. How then, can the receiver tell the two signals apart? The answer is that because of what is known as "multipath" effects, the signal from one transmitter is picked up by, let's say, two receiving antennas at the other end. One will always be slightly different to the other, maybe it's a little stronger, or has been delayed a little compared with the other one. Consider, for example, one signal bouncing off a wall behind the router, for example, against the direct signal from the other transmitter. The decoder chip in the router uses very advanced mathematical analysis to compare the signal from the two antennas, and tell the two apart. The two streams are then added together and the result is an increase in throughput.
So wherever you put your antennas, the signal will always be a little different between each antenna. The bigger the difference, the easier it is to decode. Just try to align them in different directions if possible,
e.g. like this \ | /
If you are mounting sideways, think of one antenna bent away from the wall parallel to the floor, one pointing up at 45 deg, and the other down at 45 deg (looking at it sideways). This keeps them clear of the cables. Don't worry too much about the cables being close, but not too close or touching.
[Simplified explanation of MIMO operation]
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in general 2 antennas do tx/rx and the third one do only rx (diversity)
Don't fly in anything with a Capissen 38 engine, they fall right out of the sky…
Any recommendations for the following scenarios? High Gain Antennas and/ or with extension Cable?
Its because we dont get strong signal on the other level of the Condo due to Steel reinforced Concrete in middle. I am going to try increasing Power using Tomato software, but its genuine concrete caused wi fi signal attenuation.
- Replacing ONE or MORE or ALL the Antennas with bigger antenna more DBi?
- Only replacing ONE Antenna with a CABLE extension and Antenna on different floor of 2 level Condo (Which has RCC - Reinforced Concrete in between the 2 levels. )
- Just finding a "Good Quality" dependable cable (2/3 metres) that will not have a major Gain drop. (This seems the simplest & gets signal to avoid going through the Concrete). Any dependeable extension cables?
Please recommend for above scenarios?