This invention discloses a dual-band monopole antenna, which can be operated in dual bands and easily tuned to the frequency band required for WLAN system by means of adjusting the frequencies of the resonant mode of the antenna. The dual-band monopole antenna of the invention mainly includes a microwave substrate having a first surface and a second surface, a first horizontal radiating metallic line, a second horizontal radiating metallic line, a vertical radiating metallic line, a feeding point, and a ground plane. The microwave substrate includes a first surface and a second surface. The first horizontal radiating metallic line is printed on the first surface. The second horizontal radiating metallic line is printed on the first surface. The vertical radiating metallic line is printed on the first surface, wherein the first horizontal radiating metallic line and the second horizontal radiating metallic line respectively intersect the vertical radiating metallic line at different positions. The feeding point is disposed on the vertical radiating metallic line, and a ground plane is printed on the second surface of the microwave substrate.

Dual-band monopole antenna

The invention describes a broadband multi-dipole antenna that has low input reflection coefficient, low cross polarization, rotationally symmetric beam and constant beam width and phase centre location over several octaves bandwidth. The dipoles are fed from one or a few feed points, and they may with advantage have log-periodic dimensions. The antenna is more compact, has lighter weight and is cheaper to manufacture than other solutions. It is very well suited for feeding single, dual or multi-reflector antennas.

Broadband multi-dipole antenna with frequency-independent radiation characteristics

An antenna structure including a driven antenna element is formed on a substrate that is folded to provide a closed surface, causing the substrate to be nonplanar and spacing the driven antenna element from a base of the substrate. Adhesives on an outside surface of the substrate permit fastening of the folded substrate to a container or packaging. The substrate may have one or more resilient elbows formed by folding, to bias the antenna element carrying portion of the substrate from the base of the substrate. A modulation circuit may drive the driven antenna element. The flexible substrate may be folded into any of a variety of forms such as a substantially O-shape, a substantially oval shape, a substantially coil shape, a substantially spiral shape, and a substantially S-shape. Additional folds in the substrate may provide surfaces for mounting passive or parasitic antenna elements, such as reflectors and directors, to form a Yagi antenna structure. A planar substrate carries a driven antenna element coupled to a driving circuit and at least one passive antenna element to form a directional antenna structure. The antenna structure may include additional passive antenna elements to enhance directionality. A computing system and printer are configured to determine the appropriate spacing and the form of the antenna elements on the substrate.

Antenna structure for wireless communications device, such as rfid tag

A Yagi antenna system consisting of a low noise amplifier (LNA) and a reflector co-located on the same printed circuit board (PCB) as the radiators and directors is disclosed. Furthermore, the balun cable is replaced by surface mount devices whose feed line is implemented in microstrip technology, all co-located on the same printed circuit board.

Yagi antenna coupled with a low noise amplifier on the same printed circuit board

An antenna having a dual-band driven element and a second antenna element simultaneously produces a directional radiation pattern at an upper frequency and an omnidirectional radiation pattern at a lower frequency. The dual-band driven element is formed as a dipole or monopole with at least one choke connected to the end of the dipole or monopole. In an exemplary embodiment, the dual-band driven element includes a central dipole or monopole that has chokes formed as u-shaped extensions located at the ends of the central antenna dipole or monopole. An antenna array includes the dual-band driven element and a second driven antenna element with a reflector and/or a director in a Yagi-Uda configuration. An antenna array includes the dual-band driven element with a reflector or with a reflector and a director in a Yagi-Uda configuration.

Dual-band directional/omnidirectional antenna

An antenna for TV reception predominantly in the low band and high band VHF ranges having dipoles of significantly reduced physical length as compared with conventional dipoles for reception of signals respectively in the low and high band VHF ranges. Inductive elements are employed to form a portion of the dipole length to permit significant reduction in the physical length of the dipole. The dipoles are electrically isolated from one another by suitable trap circuits to isolate high band VHF operation from low band VHF operation. Lossy components are deliberately added to the dipole section of the antenna to provide significantly improved noise matching and power transfer between antenna and amplifier. The inductive elements further provide good impedance matching between antenna and amplifier to optimize power transfer. The antenna is provided with end loads of the capacitive-type for improving both current magnitude and current distribution across the dipole in both low band and high band VHF operation. Separate amplifier channels are provided for low band and high band VHF signals to improve gain and reduce intermodulation and cross modulation effects, among other. A passive UHF section may be integrated into the array.

Miniature tv antenna

An antenna preferably designed in accordance with log-periodic principles having a superior radiation pattern and an excellent front-to-back ratio to provide exceptional performance in fringe areas. The antenna employs straight dipole arms and for VHF operation is comprised of a forward and rearward active region. The rearward active region is comprised of a plurality of dipoles having electrical lengths selected to operate in the lambda /2 mode for low band VHF reception. The forward active region is comprised of dipoles selected to operate in the lambda /2 mode for high band VHF reception. During low band VHF operation the forward active region has an insignificant effect upon the rearward active region enabling signals in the low band VHF to be of high gain and having a good front-to-back ratio, as well as providing excellent directional characteristics.

Log periodic dipole antenna array

This invention teaches an antenna array of the broadside type in which dipoles of differing electrical lengths are stacked vertically above and below an imaginary plane with electrical lengths increasing with increasing distance in moving above and below the imaginary plane. The antenna has symmetry in that for each dipole of the array below the imaginary plane, for example, there is a dipole of substantially equal electrical length and spacing approximately the same distance above the imaginary plane. Transposed feeder harness means are employed for joining adjacent dipoles and common output (input) terminals are provided in a position substantially at the location of the imaginary plane. Directional characteristics are obtained by means of Veeing the dipole arms and/or providing a vertically aligned ground screen positioned behind the antenna stack array. In another embodiment a similar array may be positioned immediately behind the first array in place of the ground screen. Directional characteristics may be obtained through coupling an output (input) utilization means to one and then the other of the arrays which are coupled at their feed terminals by means of a transposed feeder section. The array may also be joined with a conventional endfire array, for example, to form a broadside VHF endfire array and an endfire UHF array or conversely, a broadside UHF array and an endfire VHF array. Omnidirectional characteristics may be introduced if such an application is either desired or required by bending or otherwise forming the dipole arms so as to provide a substantially U-shaped configuration for each dipole. As another embodiment the ground screen may be replaced by parasitic elements arranged in a vertically stacked array with the parasitic element being provided for each dipole in the broadside array and being positioned in substantially behind its associated dipole.

Ronald D Grant

Papers

Miniature tv antenna

Log periodic dipole antenna array

Broadside log periodic antenna

Multiple tooth log-periodic trapezoidal array