A resonator comprising: an insulating layer having a top side and a bottom side; a conductive layer mounted to the bottom side of the insulating layer; a radio frequency (RF) connector designed to be connected to a transceiver, wherein the RF connector is mounted to the top side of the insulating layer, and wherein the RF connector has a center conductor that is electrically connected to the conductive layer; and means for attaching the conductive layer to a conductive structure, wherein the conductive structure has a dimension of at least one-half wavelength of an operating frequency of the transceiver such that when the resonator is attached to the transceiver and to the conductive structure the conductive structure functions as an antenna.

A resonator comprising: an insulating layer having a top side and a bottom side; a conductive layer mounted to the bottom side of the insulating layer; a radio frequency (RF) connector designed to be connected to a transceiver, wherein the RF connector is mounted to the top side of the insulating layer, and wherein the RF connector has a center conductor that is electrically connected to the conductive layer; and means for attaching the conductive layer to a conductive structure, wherein the conductive structure has a dimension of at least one-half wavelength of an operating frequency of the transceiver such that when the resonator is attached to the transceiver and to the conductive structure the conductive structure functions as an antenna.

In an embodiment, an apparatus (e.g., a gas detection device) includes a housing, a printed circuit board (PCB), one or more radio modems with a switching network. The housing includes a conductive cover and the cover plays as an antenna. The PCB may be fixed in the housing and includes a ground plane and a plurality of conductive feeds. Each feed are vertically mounted directly or indirectly on the PCB. When the cover is attached to the housing, each of the feeds electrically contact a respective connection point on the antenna. The switching network is to configure which feed should be connected to the radio modem. A extra grounding resistor is mounted or not to change antenna type to enhance the performance of antenna.

In an embodiment, an apparatus (e.g., a gas detection device) includes a housing, a printed circuit board (PCB), one or more radio modems with a switching network. The housing includes a conductive cover and the cover plays as an antenna. The PCB may be fixed in the housing and includes a ground plane and a plurality of conductive feeds. Each feed are vertically mounted directly or indirectly on the PCB. When the cover is attached to the housing, each of the feeds electrically contact a respective connection point on the antenna. The switching network is to configure which feed should be connected to the radio modem. A extra grounding resistor is mounted or not to change antenna type to enhance the performance of antenna.

An antenna structure includes a substrate, a radiation element, a conducting element, a grounding element, a first inductor, a second inductor, and a feeding element. The radiation element is disposed on the substrate. The radiation element includes a first radiation portion, a second radiation portion, a third radiation portion, and a feeding portion connected between the first radiation portion, the second radiation portion, and the third radiation portion. The conducting element is disposed on the substrate. The conducting element connects with the feeding portion. The grounding element and the feeding portion are separated from each other. The first inductor is disposed on the substrate, and coupled between the conducting element and the grounding element. The second inductor is disposed on the substrate, and coupled between the conducting element and the grounding element.

An antenna structure includes a substrate, a radiation element, a conducting element, a grounding element, a first inductor, a second inductor, and a feeding element. The radiation element is disposed on the substrate. The radiation element includes a first radiation portion, a second radiation portion, a third radiation portion, and a feeding portion connected between the first radiation portion, the second radiation portion, and the third radiation portion. The conducting element is disposed on the substrate. The conducting element connects with the feeding portion. The grounding element and the feeding portion are separated from each other. The first inductor is disposed on the substrate, and coupled between the conducting element and the grounding element. The second inductor is disposed on the substrate, and coupled between the conducting element and the grounding element.

An antenna circuit includes a radiation conductor, a matching circuit disposed between a feeding port in the radiation conductor and a feeder circuit, and a frequency-characteristics adjusting circuit connected between a frequency-characteristics adjustment port in the radiation conductor and a ground and including a variable reactance circuit. The matching circuit includes a first inductance element connected in shunt. The frequency-characteristics adjusting circuit includes a second inductance element. The first inductance element and the second inductance element are magnetically coupled to each other.

An antenna circuit includes a radiation conductor, a matching circuit disposed between a feeding port in the radiation conductor and a feeder circuit, and a frequency-characteristics adjusting circuit connected between a frequency-characteristics adjustment port in the radiation conductor and a ground and including a variable reactance circuit. The matching circuit includes a first inductance element connected in shunt. The frequency-characteristics adjusting circuit includes a second inductance element. The first inductance element and the second inductance element are magnetically coupled to each other.

This application discloses a slot antenna and a terminal. The slot antenna includes a ground plane, an open slot disposed on the ground plane, a slot feeder, and a resonant circuit. The resonant circuit effectively excites a current on a surface of the ground plane, so that the ground plane becomes a primary radiator, and the antenna is a secondary radiator. Therefore, a volume of the antenna can be reduced without affecting radiation efficiency of the antenna.

A tensor impedance surface including a plurality of unit cells, wherein each unit cell includes a dielectric having a thickness, a first surface of the dielectric having a metallic pattern on the first surface, and at least one lumped element coupled between a first point on the metallic pattern and a second point on the metallic pattern. Each unit cell of the plurality of unit cells has a first thickness and has an identical metallic pattern. Each unit cell of the plurality of unit cells is adjacent to one or more unit cells of the plurality of the unit cells.