Choosing the right wi-fi directional antenna...

Hello everyone,
I am brand new to this forum.

My task: I need to put a directional wi-fi antenna on the roof of my house to catch a wi-fi signal coming from a few miles and run an ethernet cable for 30 meter from the router to my computer downstairs.
Would the length of that cable (30 meters) impact the speed of my internet connection or will it have no effect?

I was told that it would be better to get the antenna on the roof, place the wi-fi router closer to it and then run an ethernet cable downstairs for the 30 meters distance instead of placing the wi-fi router directly downstairs because the RF signal from the antenna to the router would be highly attenuated if the cable is too long...

Any recommendations? I am also wondering about what Wi-Fi antenna I need to purchase.

Thanks,
Antennaboy

RF coax is very lossy. Ethernet cable is not. Place the radio on the roof and run CAT5 cable (good for up to 100 meters).

Use a decent radio and24 volt PoE power supply. A $90 Ubiquiti Nanobridge M2-18 would be a good suggestions.

Hello WHT,
thanks for your comments.

I have a trivial question: what is the difference between RF coaxial and CAT5 ethernet cable?

I know wi-fi is radio signal that can have 2.4 GHz or 5 GHz frequency. That is the frequency of the electromagnetic wave.
I guess the signal on the RF cable is an electrical signal at the same frequency (2.4 Ghz)....?

How about CAT5? what type of signal is it?

Thanks
antennaboy

I don't think that can be answered in less than a few paragraphs. A Google search using Wiki can get you some good answers.

antennaboy, cat5 cable is ethernet cable, as is cat6 but they are different grades.
rf cable is radio frequency co-ax (generally) - the cable that runs from your aerial to your router.

don't you just love jargon!