Q: TM backup using network drive

yup. there is.

You can do it like "Njofrekk" said but you will need some setting up first !

1. Create Sparse image bundle via Disk Utility. (File>New Image>Blank image)

2. Copy the image you created on the network drive then double click image on the network to mount it

3. You will have to go  in Terminal and enter following line:

          Sudo tmutil setdestination /Volumes/ImageName

4. Go to Time Machine and start the initial backup

Warning: This type of backup cannot be used with OsX Recovery (you will need to reinstall the OsX entirely then again mount the drive from network and then restore files via Migration Assistant).

further reading

http://pondini.org/TM/2.html

And more further reading:

Backup disks you can use with Time Machine - Apple Support

Have a nice day.