DIY wifi router with directional antenna using TP-LINK TL-MR3020 and IKEA Blanda Blank
The TL-MR3020 is a small and nifty router but the signal reach is not that good compared to other routers with better antennas. There are guides on making your own antenna for wifi-dongles and after experimenting using sieves and other parabolic dishes I found the Ikea Blanda Blank. It's cheap, performs better or equal compared to the sieves, it's smaller and it's easy to mount the router making it better looking and less fragile. You don't need to open the router nor solder anything.
Performance wise I would estimate a 5+db signal increase in the direction pointed to. For me using a Samsung S5 the reach is extended from about 100m to 420m free sight. Since the router antenna is protruding you will still have wide angle coverage. This is very handy if you have signal from another angle and want to direct it to another point.
Feel free to test coverage in more detail and share the results.
For mesh networks like Pjodd and Freifunk it's better to place the router outdoors. That's why I have included an option to make it weatherproof and also more discreet. Do note the TL-MR3020 operating temperature: -10℃~60℃.
What you need
1 - Metal drill (12mm or something similar).
2 - Mini USB cable. Get a long one if you plan to put it outside.
3 - Scissors.
4 - Waterproof double sided adhesive tape (12mm wide is nice for the stand, see step 9)
5 - TL-MR3020
6 - Ikea Blanda Blank (the smallest one)
7 - Glue gun (not necessary if the router is used indoors)
8 - Waterproof tape (not necessary if router is used indoors)
9 - Packing material from the TL-MR3020 box. This will be used as a stand. If you don't have it you need to make use of something else like an eraser cut into 3 pieces.
Lets get to work
If you don't plan to put the router outdoors you can skip step 6, 7 and 9.
1 - Carefully drill a hole in Blanda. Use eye goggles and gloves. Small metal scraps might hit your eyes. It should be located at the outer ring of the flat surface. Aim for the "wine glass" or slightly below. Make sure that your USB-plug can go through it and also move around a bit.
2 - Put double sided adheisive tape on the corners. Make sure there are no fingerprints or fat on the surface.
3 - Pull the cable through the Blanda and connect it to the router.
4 - Hold the blanda facing up and guide the router so it's centered and in line with the Blanda edge. If you are unable to do this the hole is misplaced or too small. Apply some pressure for some time according to the tape instructions to make the router stick to Blanda.
5 - If you want some more stability use the glue gun and add some glue where needed. Update: This might not be so useful. Instead use some really good double sided adhesive tape and perhaps add one piece of tape at the front over the router and the Blanda bowl like http://wiki.pjodd.se/mediawiki/index.php/Fil:Blandtenna_10.jpg
6 - For outdoor use cover the hole with some glue.
7 - For outdoor use cover the front with tape. Make sure to cover all the gaps. It might be difficult though so one option is to make a small hole at the bottom so any accumulated water can drip out. For an alternative look at "Alternative weatherproofing".
8 - Cut the packing material in half. Place it aligned with the router (horizontal) onto Blanda and add some glue.
9 - For outdoor use put some double sided adhesive tape under the stand.
If you want to hide Blandtenna you can use Ikea Skubb:
Drill a 4-5mm hole in the Blanda and also in the thing you want to use for mounting. Add a screw and a self locking screw nut. Don't forget about the orientation if you already made the cable hole.
This is an alternative to using waterproof tape. Get some liquid tape. Follow the instructions on the can. You can spray only the router before you mount it but apply the double sided adhesive tape first with the protection tape still on. Keep a usb-cable in the usb-port.
In this case I mounted the router first and put glue to cover the base of the router, protecting the LAN port and then applied the liquid tape as I wanted the Blandtenna completely black.