OK! English is not my motherlanguage.
You have to use 50 Ohm antena with 50 Ohm cable as modem output is also 50 Ohm impedance. Logoperiodic is better then others for this purposes. Home-made YAGI well known for this bad mismatch issue. I will not recomend to make YAGI at the garage - it require very good experience.
NB! VERY good quality antenna cable have to be used!!!! And not more than 1-2m.
You have to use 50 Ohm antena with 50 Ohm cable as modem output is also 50 Ohm impedance. Logoperiodic is better then others for this purposes. Home-made YAGI well known for this bad mismatch issue. I will not recomend to make YAGI at the garage - it require very good experience.
NB! VERY good quality antenna cable have to be used!!!! And not more than 1-2m.