An antenna structure includes a metallic member, a feed portion, and a coupling resistor. The metallic member defines a slot, a first gap, a second gap, and a third gap. The first gap and the second gap are connected with the slot and divide with the slot the metallic member into a first portion and a second portion. The second portion is grounded. The third gap is defined on the first portion and connected with the slot. The first portion is divided into a radiating portion and a coupling portion by the third gap. The coupling portion is spaced apart from the radiating portion. The feed portion is electrically connected to the radiating portion, and the coupling portion is grounded through the coupling resistor.

An antenna structure includes a metallic member, a feed portion, and a coupling resistor. The metallic member defines a slot, a first gap, a second gap, and a third gap. The first gap and the second gap are connected with the slot and divide with the slot the metallic member into a first portion and a second portion. The second portion is grounded. The third gap is defined on the first portion and connected with the slot. The first portion is divided into a radiating portion and a coupling portion by the third gap. The coupling portion is spaced apart from the radiating portion. The feed portion is electrically connected to the radiating portion, and the coupling portion is grounded through the coupling resistor.

An antenna and an apparatus, where the antenna includes a radiating area, a grounding area, and a feeding area, at least one variable impedance circuit is disposed in at least one of the radiating area, the grounding area, and the feeding area, and the variable impedance circuit is configured to: when impedance of the antenna does not match impedance of a radio frequency front end, or when impedance of a radio frequency front end changes, adaptively adjust the impedance of the antenna, control the impedance of the antenna to match the impedance of the radio frequency front end in a conjugate manner. Alternatively, the variable impedance circuit is configured to: when impedance of the antenna matches impedance of a radio frequency front end, adaptively adjust the impedance of the antenna, control the impedance of the antenna to mismatch the impedance of the radio frequency front end.

An antenna and an apparatus, where the antenna includes a radiating area, a grounding area, and a feeding area, at least one variable impedance circuit is disposed in at least one of the radiating area, the grounding area, and the feeding area, and the variable impedance circuit is configured to: when impedance of the antenna does not match impedance of a radio frequency front end, or when impedance of a radio frequency front end changes, adaptively adjust the impedance of the antenna, control the impedance of the antenna to match the impedance of the radio frequency front end in a conjugate manner. Alternatively, the variable impedance circuit is configured to: when impedance of the antenna matches impedance of a radio frequency front end, adaptively adjust the impedance of the antenna, control the impedance of the antenna to mismatch the impedance of the radio frequency front end.

Various embodiments are described that relate to an antenna. In one embodiment, the antenna can be a low profile, multi-band (e.g., dual band), emulated GPS constellation antenna. In one embodiment, the antenna can form a cube with two open sides and four circuit board sides. The four circuit boards can include a first hardware portion that allows functioning in a higher frequency band and a second hardware portion that allows functioning in a lower frequency band.

Various embodiments are described that relate to an antenna. In one embodiment, the antenna can be a low profile, multi-band (e.g., dual band), emulated GPS constellation antenna. In one embodiment, the antenna can form a cube with two open sides and four circuit board sides. The four circuit boards can include a first hardware portion that allows functioning in a higher frequency band and a second hardware portion that allows functioning in a lower frequency band.

An antenna switching circuit comprises a detection device, a controller, a first antenna, a second antenna, a first switch and a radio frequency transceiver. The detection device is used to detect a change in an input impedance of the first antenna and a change in an input impedance of the second antenna; the controller is used to compare the change in the input impedance of the first antenna with the change in the input impedance of the second antenna; the first switch is used to turn on a first radio frequency circuit and turn off a second radio frequency circuit when the change in the input impedance of the first antenna is less than the change in the input impedance of the second antenna.

An antenna switching circuit comprises a detection device, a controller, a first antenna, a second antenna, a first switch and a radio frequency transceiver. The detection device is used to detect a change in an input impedance of the first antenna and a change in an input impedance of the second antenna; the controller is used to compare the change in the input impedance of the first antenna with the change in the input impedance of the second antenna; the first switch is used to turn on a first radio frequency circuit and turn off a second radio frequency circuit when the change in the input impedance of the first antenna is less than the change in the input impedance of the second antenna.

A folded antenna is provided including an antenna having a fold therein. The fold in the antenna divides the antenna into first and second radiating portions. The first radiating portion of the folded antenna is planar and the second radiating portion has a window therein. The first and second radiating portions of the folded antenna are coupled at the fold in the antenna having a predetermined angle therebetween. Related antenna systems and meters are also provided.

A folded antenna is provided including an antenna having a fold therein. The fold in the antenna divides the antenna into first and second radiating portions. The first radiating portion of the folded antenna is planar and the second radiating portion has a window therein. The first and second radiating portions of the folded antenna are coupled at the fold in the antenna having a predetermined angle therebetween. Related antenna systems and meters are also provided.