What is a heavy duty USB Wi-Fi antenna?

Question

System administration

Here's what I'm thinking about. I live in a big city and I have a MacBook Pro Retina late 2013 and I don't always have internet nearby. I thought about buying a 3G modem, but the more or less powerful macbook network card hints that there are a lot of WiFi around and some even without a password. The MacBook sees about 2 times more dots than the iPhone.
I came up with the idea to buy a very powerful WiFi adapter and use it to suck the Internet out of the world's airwaves. I rummaged through dx.com - there are many offers, which of them really work to the fullest - it is not known.
1) Recommend a very powerful USB Wi-Fi antenna with minimal power consumption (as I understand it, the standard should be ac), which will work out of the box under OS X and Linux.
2) What is the difference between dbi and dbm?
3) How harmful is such an antenna to humans?
4) Is power a significant indicator or can a 5W antenna be worse in reception than 1W?
5) How much will this affect the autonomy of the MacBook?
6) Do I need to look for exactly the "ac" adapter, or will it still be of no use if there are a maximum of "n" routers around?

Answer 1

here?
www.tinydeal.com/ru/80211-bgn-wlan-wifi-adapter-...

Answer 2

1) It is difficult to advise something specific, but for the same Linux, you can take almost any WiFi whistle on popular chips (Realtek, Ralink, Atheros) and just look on the Internet to see if there is support for this chip in the kernel. Here, "nonameness" is even more useful, since standard VID and PID are used in unnamed adapters, and in branded ones they can be "branded". And a situation arises when there is support for the chip, but the system does not recognize it because of the left identifiers.
From general considerations, I can advise you to look for adapters, in the characteristics of which something like "RF output power: max.20dbm" will be written and buy a separate "20db" omnidirectional antenna for them.
2) aerial.dxham.
3) "And the devil knows." In theory, everything that fits into the norms allowed for use is not harmful even with constant use. So up to 20 dBm (100 mW) everything can be bought safely.
4) Yes, it is. If the antenna is well made and used correctly, then no, it cannot.
5) Well, it will somehow affect in the direction of reducing the operating time. But if you disable the built-in module when connecting an external one, then you most likely will not notice the difference.
6) In the realities of the modern world, you can even take b / g. For it is quite difficult to find a network that would give out an honest speed even for n. And in free / passwordless it's generally fantastic.

Answer 3

Some time has passed, but maybe for someone the question is still relevant, so I will express a subjective opinion:
I just tried a number of adapters from dx.com, mainly for the purpose of obtaining highly stable links at medium distances due to excessive power. First of all, I confirm that there is no power higher than 23dbm (200mW) among the adapters sold there, and it seems that 200mW is no longer available. Loud inscriptions 1000mW, 2000mW, 7000mW (!) This is a half-truth, in fact it is a very rough equivalent of the radiated power, already taking into account the directional antenna supplied with the adapter, and still a hoax.
Some adapters allow, after alteration with a soldering iron, to give out more, in particular on the RTL8187 chip. Of course, you need to take care of finding software that allows you to set power without restrictions, but at the risk of burning the transmitter chip. The alteration consists in installing a heatsink on the chip and supplying 5V via a thick wire directly from the power system (always with a common minus with the connection to USB).
In general, I preferred to take only Realtek, because Ralink had previously shown themselves to be a less stable work. From Realtek, in addition to 8187, I tried 8188, 8191, which did not allow the means I had to arbitrarily increase the power, although the receiving sensitivity seemed to be higher.
And of course, you need to watch with a screw-down antenna, because it is better to choose the antenna separately. You can also buy an amplifier there., which by itself shows what the real cost of honest power is. Such an amplifier should be used in conjunction with the most sensitive adapter with an output power of 100mW. Together with a directional antenna, it will allow you to reach a significantly larger number, even redundantly, but its usual use is long-distance radio links ...