Patent ID: 8476905

Claim:
A signal transmitting and receiving circuit for transmitting and receiving signals, the signal transmitting and receiving circuit comprising: a tuning and matching circuit for transmitting and receiving the signals; a signal communication wire for transmitting the signals; a wavelength wire having a length L defined as L=N*(λ/4), where N is a positive integer and λ is a wavelength of the signals; and a switch part for changing over between a grounded connection and an ungrounded connection, wherein: the tuning and matching circuit is connected to the signal communication wire, a first end of the wavelength wire is connected between the tuning and matching circuit and the signal communication wire, and a second end of the wavelength wire is connected to the switch part, if N is an odd number, the switch part changes over to the grounded connection in use and the ungrounded connection in nonuse, and if N is an even number, the switch part changes over to the ungrounded connection in use and the grounded connection in nonuse.