Wireless connection much slower then with cable, is this normal?

A few days ago I purchased a wireless modem, modem, not router. It's called HG520s. First thing I noticed was the low ping and download speed, comparing to how it was on cable. I googled about it, and understood that as far the modem is, as low the connection is. So I took the modem and placed it in the room I'm using the notebook in. The distance between the modem and the notebook is less then 2 meters. Yes, the connection did increase, but still not like it was on cable. Before, I had only A grade pings (30-40), now i can hardly get a C (70-100). My download speed was 1.2 Mb/sec now it's arround 500-600 Kb/sec (this on real download speed, I don't know what those speeds from speedtest.net mean as mine are much lower then what they show there).
It's not really a big problem, as I can always connect the cable back but I run the desktop and the notebook at the same time regularly, and I want net connection on both of them. Is it normal to get such low connection from a wireless modem, or I did something wrong?

 

The quality of your wireless connection will greatly depend on the hardware you are using(modem/router/adapter).

However to answer your question, yes the wireless equipment available to the public will be slower then an ethernet cable connection. At the moment if you want raw performance always go with a wired connection.

 

Wireless connections will always be worse off than a wired one.

 

the wireless connection, it is wireless signal. so it will affected by any other devices that use wireless signal. for example, wireless phone, microwave and etc.....