# Can the Q of a loop antenna be changed?

Can the Q of a loop antenna be changed?
If so what are some common techniques? (Formulae appreciated).

• Hi! Welcome here :) . As on any other SE site, we do appreciate very much when askers explain what they've researched so far, so that we don't tell them things that they already know. So, have you researched how the Q of a loop antenna "happens"? If so, what were your thoughts on changing it? What problems did you see, and what exactly do you need info on :)? Jun 22 '18 at 8:16
• There are many types of loop antennas. Based on the question, you mean a small loop HF antenna of a meter or two in diameter? Jun 22 '18 at 10:36
• The antenna is composed of multiple loops about 4 cm in diameter. It is for an rfid tag at 13 MHZ Jun 22 '18 at 13:47
• I'm not even sure that what you're describing is technically an antenna (although it's usually called antenna, for sure); it's more of the secondary side of an air-core transformer (there's a magnetic field between reader and tag, but the coil's purpose is not to extract power or radiate power in shape of an electromagnetic wave) . So, not even sure it has a Q; can you point us to some kind of description of the loop? Jun 23 '18 at 8:12
• Also, if this really is about RFID, I'd argue it's very specific to a field of electrical engineering that is neither amateur radio nor radio theory in general (as applicable esp. to ham radio), so I think it would find much better answers on electronics.stackexchange.com Jun 23 '18 at 8:13

An RF tag system is designed to function in the near field of the antennas. The frequencies involved are in the 13 MHz range and the antennas used in these applications are defined as electrically short antennas (<0.1 $$\lambda$$).