External antennas for your 4G router: the 20-minute test that beats buying the kit

Every stall selling "signal booster antenna" kits rests on one truth: a router with weak reception can improve by a metre of relocation, and the same router with the wrong antenna kit can stay exactly as bad. Before the wallet opens, run the test that tells you which machine you own - because the diagnosis changes the purchase from an antenna to nothing at all, or to one very specific thing.

Step one: does your router even have the option?

Look for two small coaxial ports - usually TS9 or SMA, behind a flap, sometimes only present on the "pro" revision of the consumer model. No ports means the internal antenna is the only body your router has, and every external kit becomes a dongle gamble or a new router, not an antenna. And the honest check the sellers skip: ports that exist on the stock photo but not your exact hardware revision - look at the device, not the listing.

Step two: the 20-minute free experiment

• Placement before gain. The mast's direction beats everything: walk the router to a high point on the side of the house facing the mast - first floor, shelf height, off the metal shelf, away from the TV - and read the signal figures in the router's admin page before and after. The numbers are dBm, and less negative is better: -105 is a bad day, -75 is a strong one.
• The hand test. Move your hand between the router and the mast, watching the readings: if a hand drops a bar, the building skin was doing what the antenna box promises - and a window-mounted external antenna genuinely helps. If nothing moves, the signal arrives rich from its direction and an antenna is theatre.
• The night reading. Mobile data is a shared cell: record the numbers at 8pm for three nights before deciding the router is the problem - a congested tower answers to a better antenna the way a queue answers to a louder voice: not at all.

Step three: if you still buy, buy right

External antennas are not generic: a kit must match your carrier's bands, the connector type (TS9 versus SMA is a genuine and common dead end), and - the part nobody mentions - cable loss matters more than the pretty dome: coax from the roof to the desk can swallow the entire gain the antenna adds, which is why a short cable to a window-mounted panel usually beats the big antenna on the pole with twenty metres of thin wire. The one spec worth money on the box is gain in dBi for your band, and the one honest review is your own admin page's readings before and after, same spot, same hour - the instrument has been built into your router all along, and it is the only judge this desk trusts.