An antenna apparatus, which can increase capacity in a cellular communication system or Wireless Local Area Network (WLAN), such as an 802.11 network, operates in conjunction with a mobile subscriber unit or client station. At least one antenna element is active and located within multiple passive antenna elements. The passive antenna elements are coupled to selectable impedance components for phase control of re-radiated RF signals. Various techniques for determining the phase of each antenna element are supported to enable the antenna apparatus to direct an antenna beam pattern toward a base station or access point with maximum gain, and, consequently, maximum signal-to-noise ratio. By directionally receiving and transmitting signals, multipath fading is greatly reduced as well as intercell interference.

Adaptive antenna for use in wireless communication systems

An antenna having at least one main element and a plurality of parasitic elements. At least some of the elements have coupling elements or devices associated with them, the coupling elements or devices being tunable to thereby control the degree of coupling between adjacent elements. Controlling the degree of coupling allows a lobe associated with the antenna to be steered.

Meta-element antenna and array

A reactively controlled directive antenna array that has a single central monopole or dipole as a radiating element excited directly by a feed system. A plurality of parasitic elements surround the radiating element and through changing the state of the parasitic impedance causing the antenna to be in an omni directional or beam pointing mode according to whether the parasitic elements are open circuited or short circuited. A computer modem and memory including stored programs control the antenna array in an omnidirectional or directive mode to locate, identify and communicate with nodes in a wireless communication network. A stored table is created in the memory indicating the antenna direction for communicating with each node in the network. Using the stored table, the computer initiates a communication sequence with a selected node, the sequence having the advantages of improved signal sensitivity and angular discrimination for wireless communication systems.

Communication system and methods utilizing a reactively controlled directive array

An enhanced backscatter RF-ID tag reader system and multiprotocol RF tag reader system is provided. In a multiprotocol mode, the system emits a non-stationary interrogation signal, and decodes a phase modulated backscatter signal by detecting a stronger phase component from quadrature phase representations or determining phase transition edges in a phase of a received signal. The RF tag reader system predicts or follows the phase of the backscatter signal, thereby avoiding interference from nulls in the received signal waveform due to the non-stationary interrogation signal, relative movement or environmental effects. An acoustic RF-ID tag detection system detects the reradiated signal corresponding to respective transformation of a signal in the tag. Detection of either type of RF-ID tags therefore is possible, and the absence of any tag or absence of any valid tag also determined.

Dual mode transmitter-receiver and decoder for RF transponder tags

Antenna arrangements for use with portable communications devices are described. In one embodiment, an antenna (50) has four equally spaced monopole elements (52-58) mounted in a regular array on the outer surface of a solid cylinder structure (60). The cylindre (60) has a high dielectric constant, and extends from a conductive ground plane (62). The monopole elements (52-58) can be switched by switching elements (64-70, 76) so that one or more is active, with the others acting as parasitic directors/reflectors being connected commonly to ground or left in an open circuit condition to be effectively transparent. A shielded single monopole antenna (10) is also described.

Antennas for use in portable communications devices

A resonant microstrip radiator wherein the size of the radiator is reduced in the resonant or non-resonant dimensions, or both, without reducing the effective resonant dimension or substantially lowering the efficiency of the radiator. Reduction of the resonant dimension is provided by folding the resonant cavity, while reduction of the non-resonant dimension is facilitated by utilization of a low density, low loss dielectric, such that the loss resistance of the element is appreciable with respect to the radiation resistance of the element. Also disclosed are interdigitated antenna structures and provisions for circularly or elliptically polarized radiation.

Microstrip radiator with folded resonant cavity

A resonant cavity having at least one radiating antenna slot formed in a wall of the cavity includes an electrically conducting plate disposed within the cavity and substantially spaced from all internal cavity walls so as to effectively lengthen the electrical resonant dimensions of the cavity for a given physical size. This slotted cavity antenna permits the use of simplified feeding structures, provides a more efficient antenna structure and reduces the necessary physical dimensions of the structure for operation at a given frequency.

Slotted cavity antenna

A directional scanning antenna includes a circular array of a plurality of antenna elements extending several wavelengths in diameter. The number of antenna elements are sufficient to form a plurality of directionally-oriented subsets of active antenna elements and associated subsets of parasitic antenna elements. An antenna feed system provides connections to each one of the plurality of antenna elements that include connections to electronically variable reactances and connections to a source or receiver of electromagnetic energy. The antenna feed system is controllable to provide connections between the subsets of active antenna elements providing wave propagation and reception in one or more directions and to provide connections between a plurality of the remainder of antenna elements in associated subsets of parasitic antenna elements to assist the directionality of the antennas.

Directional scanning circular phased array antenna

Radio frequency antenna arrays of radiating slot apertures serially connected along a predetermined path transverse to the radiating slot apertures. In the exemplary embodiments, the radiating slot apertures are formed by parallel edges of conductive radiator surfaces where the edges are spaced apart by substantially one-half wavelength at the anticipated antenna operating frequency. Such radiator surfaces are, in some embodiments, dimensioned in a direction parallel to the apertures in relation to the relative proportion of radio frequency energy which is to be radiated to/from the slot apertures associated therewith to thus determine the total array aperture amplitude taper while the spacing between the radiator surfaces determines the phase taper across the total array aperture. Other exemplary embodiments utilize internal reflections in an array to determine the array amplitude taper and still other exemplary embodiments combine a plurality of such arrays to form two-dimensional special purpose arrays.

Serially connected microstrip antenna array

A raised patch antenna is disclosed which includes a base having a ground plane, a plurality of leg supports interconnected to and extending upwardly to the base, a raised patch antenna element supportedly interconnected to the leg supports and positioned over the ground plane and an RF feed comprising a feed-leg portion provided on the leg supports and a feed base portion provided as a part of the base. The RF feed includes impedance matching components for matching the impedance of the feed base portion with the impedance with the raised patch antenna element in series with the feed-leg portion. The feed-leg portion comprises at least a first pair of balanced feed-leg lines interconnected to opposing sides of the raised patch antenna element. Baluns can be provided in said feed base portion for balancing. For circularly polarized applications, a second pair of balance feed-leg lines are interconnected to second opposing sides of the raised patch antenna element for excitation of orthogonal modes, and a phasing means is provided in the feed base portion for achieving phase quadrature. The antenna yields broad overhead coverage and satisfactory bandwidth, and can be economically and readily produced.

Gary G. Sanford

Papers

Microstrip radiator with folded resonant cavity

Slotted cavity antenna

Directional scanning circular phased array antenna

Serially connected microstrip antenna array

Raised patch antenna