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Thread ID: 143043	2016-11-05 23:38:00	Maximising router range with an external antenna?	Johnnz (7246)	Press F1

Post ID	Timestamp	Content	User
1428420	2016-11-08 09:02:00	But what about the return traffic from 200m away? How is that going to be achieved?	linw (53)
1428421	2016-11-08 19:06:00	But what about the return traffic from 200m away? How is that going to be achieved? The great thing about antennas is they amplify in both directions - transmit and receive	BBCmicro (15761)
1428422	2016-11-08 20:00:00	Hadn't thought of that, BBC. A weak signal coming back gets picked up by a good aerial. Seems obvious if you give it a little thought!!	linw (53)
1428423	2016-11-08 20:35:00	some techy questions for BBCmicro . Just wondering Beamforming: I get the concept . But how will the Access point(transmitter) know where to form the beam to ? how does it know where the other device is, so the beam can be directed at it. And with beamforming , you are creating overlaps of the 'beams' where they add , but that will give dead spots where the beams subtract (are out of phase)? Also , if the antennae is up high , and the receiver/ph is down at say 3ft , then I guess signal must be pointed down towards the ground , unless the receiver is some distance away . So with an antennae up high, and a small 2.4G or 5.8G wavelength , then would it have to be optimised for either the receiver up close, or far away ? Is the db gain from height just due to Fresnal zone , of something else ?	1101 (13337)
1428424	2016-11-10 01:23:00	As I understand it, there's 20 dB or more difference between the various wifi modes so the setting-up of a connection might be done under the old 802.11b standard then if the error rate is low enough the equipment might transfer to 'n' to get decent bitrate. The beam could be steered during the set-up phase (It is possible that the beam-forming is designed to minimise interference rather than provide a lot of gain. I don't know enough about it. Minimising interference can achieve many more dB than maximising the wanted signal) Yes the beam will have serious holes in the service area but if the peak of the beam is always directed at the distant cellphone, who cares? At 2.4 GHz or 5 GHz the transmission is essentially line-of-sight. Putting the router on the highest point of the roof is just a way of getting line-of-sight in all directions and over obstacles. There is no gain due to height itself. The router's beam never needs to be pointed down (can always be directed at the horizon) because the short length (120 mm) of the antennas doesn't create any nulls unless the cellphone is very close to the house (say 20m). Even then, the closeness of the cellphone to the antenna will outweigh the negative effect of the null An idea I've sometimes wondered about is to have a fixed antenna - a single vertical rod - and a rotating reflector behind it similar to the way that flashing lights on cop cars used to operate. If the beam from the reflector were 12° wide then it would be pointing at the cellphone for 1/30th of the time. So a normal throughput of say 1.5 Mbps would reduce to 50 Kbps. The reflector could provide 20 dB gain and provide seriously-long-distance service over a 360° arc. I don't know how TCP would handle it though Question: why not use mobile data rather than wifi? It's much cheaper than it used to be	BBCmicro (15761)
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