PCS-Electronics

I have bought a better FM transmitter now from here http://www.ebay.com/itm/201718864977?ul_noapp=true
It work wery well, but i need a good antenna for this?
Can you recommend a good one?
Whit that i have now i transmitt about 3miles when i use 5w(have 15w to use to)

Ok, i have test it how far it goes, and it transmitt ca 984ft and that is good to be so little

I have a littel FM transmitter i think is 0,5w(not sure)
Can i upgrade it with more power on it?
http://i67.tinypic.com/27ya7ut.jpg
http://i67.tinypic.com/mjvl8n.jpg


The transistor is a 2N2222A