{"id":7,"date":"2013-01-28T21:35:30","date_gmt":"2013-01-28T21:35:30","guid":{"rendered":"http:\/\/asdfghjkl.me.uk\/blog\/?p=7"},"modified":"2021-03-28T17:51:21","modified_gmt":"2021-03-28T16:51:21","slug":"antennas","status":"publish","type":"post","link":"https:\/\/asdfghjkl.me.uk\/blog\/antennas\/","title":{"rendered":"Cheap Chinese eBay antennas – a complete waste of money?"},"content":{"rendered":"

I live in a zoo. For the most part this is super cool<\/a>, but it's in the middle of nowhere and the internet access leaves a bit to be desired. I started using a 3G dongle, but the signal is rubbish and it drops out whenever it rains.<\/p>\n

\"3G<\/a>

Zero bars, aww yeah<\/p><\/div>\n

I started looking into ways to boost the signal, discovering that many mobile broadband users in rural Australia use Yagi antennas. These are highly directional and, if used correctly, can pick up signals from towers several kilometres away. I didn't have the tools available to DIY one, so turned to eBay for a sketchy Chinese alternative. What I got was this:<\/p>\n

<\/p>\n

\"Chinese<\/a>

Why would a beauty shop even be selling antennas?<\/p><\/div>\n

When it eventually arrived, I quickly discovered that it didn't work. At all. I opened up the mysterious grey plastic box that the coax feeds into to find the core soldered to one end of the driven element, the shield soldered to the other, and a little bit of thin coax soldered to both - presumably for some cheap impedance matching between the cable and antenna. Whatever it was doing, it wasn't doing it very well. I tried replacing it with a half-wave coax balun as detailed here<\/a> (original link<\/a>, photos lost to the mists of time):<\/p>\n

\"Half-wave<\/a><\/p>\n

\"DIY<\/a>

Ignore the dodgy soldering.<\/p><\/div>\n

I could now pick up signal, but it wasn't any better than just hanging the dongle out the window. I don't know if it was the fact that the elements were just crimped on, or that the spacing between them hadn't been measured at all, but the speeds I got with the antenna connected were somehow worse.<\/p>\n

\"Speed<\/a>

With yagi... (still somehow faster than 90% of the UK?!)<\/p><\/div>\n

\"Speed<\/a>

...and without. That ping's good enough to play TF2!<\/p><\/div>\n

So I went back to the dongle. I guess it's not bad if you position it right (duct taped to the window with a sieve over it, apparently).<\/p>\n

Thing is, I'm moving into a house (also in the zoo) soon, which is slightly out of Three's range - and in any case, the 10GB\/month allowance is nowhere near enough for 4 people! My plan is to borrow wifi from one of the hotspots dotted about, which will of course require another high-gain antenna. I was a bit more careful in my search this time round, so I'm sharing my findings in case anybody else has the same issue.<\/p>\n

So we've already established that any antenna with the mysterious grey plastic box is likely to be worthless. I had a look around, and well-reviewed antennas all seem to have a solid bit of aluminium at their feedpoint.<\/p>\n

\"Aluminium<\/a>

Like so.<\/p><\/div>\n

Similarly, antennas with the elements riveted on are better than those which are just crimped. I wasn't entirely sure about this since DealExtreme has been sending out both versions<\/a>\u00a0(reviews are a bit mixed, but I'm not sure who's had what), but since crimping seems to be a cost-saving measure, I'd go for rivets wherever possible.<\/p>\n

\"Crimped<\/a>

Crimped...<\/p><\/div>\n

\"Riveted<\/a>

...vs riveted.<\/p><\/div>\n

You can split those with an aluminium feed into 2 groups: those with heatshrink over the bottom of the driven element; and those without. This guy<\/a>\u00a0thinks the heatshrink is where the feed's taking place, and it's only the cheaper antennas (though we're only talking a couple of pounds difference here) that don't have it. Again, something to look out for.<\/p>\n

\"Driven<\/a>

No heatshrink here.<\/p><\/div>\n

\"Driven<\/a>

Better!<\/p><\/div>\n

Of the antennas with an aluminium feed, riveted elements and heatshrink over the driven element, there seem to be two major models made by two companies: AMY and TDJ. This guy<\/a>\u00a0sells antennas in Malaysia (also fairly spotty coverage) and says that the AMY brand is better, plus he gives a few ways of differentiating between them:<\/p>\n

\"AMY<\/a>

AMY antennas have model numbers along the lines of AMY-2400-16.<\/p><\/div>\n

\"AMY<\/a>

AMY antennas have rounded plastic caps, whereas TDJ caps come to a point.<\/p><\/div>\n

\"Short<\/a>

AMY antennas have a shorter bit of heatshrink on the feed than TDJ.<\/p><\/div>\n

\"Long<\/a>

(okay, I admit it's getting a bit ridiculous now)<\/p><\/div>\n

A couple of extra things to look out for:<\/p>\n