Google will tell you everything...how you think everyone finds out...magic word "Research''
Cantenna actually works if your far away from the AP you just have to sit and adjust the angle of it until you get perfect signal as it directs the signals in more of a straight line as opposed to not using one where you can catch signals floating. The signal will drop out less with a cantenna once you find the perfect setting point to a specific AP, they are very easy to make, I suggest mounting it on a 'selfy stick' so you can adjust angle and twist it left and right.
The YAGI antenna is incomparable to a CANTENNA IMO because they are a hundred times more effective but cannot really be made from trash laying around your house. I have seen one but it still consisted of more or less parts most people would have to go buy from a hardware store.
You can actually get much more effective results from irradiating any interference's around your home and get the device high up away from other signals that interfere. Don't use really long extension cords for the adapters if its a USB type as this reduces the power unless its already high dbi I personally wouldn't extend it.
With most USB adapters i've split open, you will notice a small circular connection to the board, this is a test port/ external antenna port, in SOME cases you can go to a computer store and buy an antenna to fit that and this will greatly improve your signal receptions. Sometimes it doesn't work so research your model first to see if anyone else has had success, the external antenna's are usually pretty cheap too, they have the fittings on most Samsung galaxy phones but these cannot be used anymore as due to a software floor once you start using that port with an external antenna your phone will no longer use the built in radio antenna and then you'll have to go about your day with an external antenna device duct taped to yourself or your phone just to get a signal.
Make sure you take the adapters board out of its plastic case when making a CANTENNA otherwise you will see no benefit. Trial and error which way to fit it into your cantenna for best results as facing the radio directly out of the cantenna face isn't always the best. Was a while back since I did the cantenna trick but it definitely works.
Good luck Regards HashMan
