A wideband monopole antenna, formed on a first surface of a circuit board substrate with the first surface at least having a signal ground portion, wherein the wideband monopole antenna comprises: a feeding portion, coupled to a feeding cable, the feeding portion at least having a first side and a second side; a first radiating portion, extending from a first end coupled to the feeding portion to a second end, the first radiating portion at least has a third side, the third side being connected to the first side of the feeding portion, the first side, the third side, and the signal ground portion defining a first slot; and a second radiating portion, extending from a third end coupled to the feeding portion to a fourth end, the second radiating portion at least has a fourth side, the fourth side of the second radiating portion and the signal ground portion defining a second slot therebetween; wherein the spacing between the third side of the first radiating portion and a fifth side of the signal ground portion in the first slot is not less than a first distance while the spacing between the fourth side of the second radiating portion and a sixth side of the signal ground portion in the second slot is not less than a second distance so that voltage standing wave ratio (VSWR) of the wideband monopole antenna within a frequency band is less than a first threshold; further, the signal ground portion further comprises an impedance matching structure adapted for improving the signal radiation field, and the impedance matching structure is connected to the fifth side and having a seventh side being adjacent to the second end of the first radiating portion and the fourth end of the second radiating portion and in parallel to the sixth side; wherein, the circuit board substrate has an opposite second surface in addition to the first surface; and radiation field associated data signal emitted by the wideband monopole antenna is enhanced since the second surface has a clearance region located opposite to the region of the wideband monopole antenna on the first surface of the circuit board substrate; and the wideband monopole antenna is arranged between the sixth side and the seventh side. a feeding portion, coupled to a feeding cable, the feeding portion at least having a first side and a second side; a first radiating portion, extending from a first end coupled to the feeding portion to a second end, the first radiating portion at least has a third side, the third side being connected to the first side of the feeding portion, the first side, the third side, and the signal ground portion defining a first slot; and a second radiating portion, extending from a third end coupled to the feeding portion to a fourth end, the second radiating portion at least has a fourth side, the fourth side of the second radiating portion and the signal ground portion defining a second slot therebetween; wherein the spacing between the third side of the first radiating portion and a fifth side of the signal ground portion in the first slot is not less than a first distance while the spacing between the fourth side of the second radiating portion and a sixth side of the signal ground portion in the second slot is not less than a second distance so that voltage standing wave ratio (VSWR) of the wideband monopole antenna within a frequency band is less than a first threshold; further, the signal ground portion further comprises an impedance matching structure adapted for improving the signal radiation field, and the impedance matching structure is connected to the fifth side and having a seventh side being adjacent to the second end of the first radiating portion and the fourth end of the second radiating portion and in parallel to the sixth side; wherein, the circuit board substrate has an opposite second surface in addition to the first surface; and radiation field associated data signal emitted by the wideband monopole antenna is enhanced since the second surface has a clearance region located opposite to the region of the wideband monopole antenna on the first surface of the circuit board substrate; and the wideband monopole antenna is arranged between the sixth side and the seventh side.