What does "U" mean on a circuitboard?

Question

R means resistor, C means capacitor, Q means transistor. What does U mean?

Answer 1

I have seen U reference an IC on a schematic. So its possible these references have been silk screened onto a PCB.

Some others:

J - Jack or socket, may also refer to a header

D - Diode

X - transformer

B - Battery

XTAL - crystal

S - switch

Answer 2

Probably an integrated circuit.  But you are more likely to overload it and destroy it than increase its range.  Your best bet is to buy one designed for the purpose.  

Answer 3

possibly antenna suggest wikipedia electronics circuit symbols does not show up exact form [shape] in question