A technique is investigated for controlling the operating frequency and polarization of microstrip antennas. The control is achieved by placing shorting posts at appropriate locations within the antenna's boundaries. By changing the number and locations of the posts, the operating frequency can be tuned over a 1.5-to-1 range, and the polarization can be changed from horizontal to vertical, right-hand circular, or left-hand circular. All of these changes are obtained without significantly altering the input impedance or radiation patterns of the antenna and without increasing the complexity of the external microwave feed network. The frequency and polarization can be electronically controlled by using microwave switching diodes for the shorting posts. Antennas that have two feeds and operate simultaneously in two orthogonal polarizations have been constructed with the capability to switch between linear and circular polarization. Also, a thin frequency-scanned array has been built with the frequency-agile microstrip elements.

/pdf/microstrip-antennas-with-frequency-agility-and-polarization-53jc5uv7ha.pdf

Microstrip antennas with frequency agility and polarization diversity

A radio frequency antenna for use with a wall mounted transmitter and/or receiver for receiving and/or transmitting signals adapted to control a control device and/or indicate status of the control device. The antenna includes an insulating substrate sized to fit within an area defined by a faceplate sized to cover an outwardly facing opening of an electrical wallbox. Conductors are disposed on both sides of the substrate forming a capacitive component. At least one of the conductors is adapted to radiate radio frequency energy into the environment. The one conductor is electrically coupled to the other conductor, and the one conductor has a pattern such that the conductor is absent in areas so as to provide the antenna with an inductive component. The at least one conductor further provides a connection to the transmitter and/or receiver. The antenna provides an antenna near-field which is substantially at the edges of the substrate and which provides insubstantial electromagnetic field coupling to an electronic circuit disposed adjacent the antenna connected to the antenna and further provides a radiated field substantially isotropic in the antenna far-field.

Compact radio frequency transmitting and receiving antenna and control device employing same

Hybrid mode feeds which are capable of handling very wide bandwidths. In the present feed arrangements, a dominant TE11 mode is converted to the HE11 hybrid mode which is then launched. The TE11 to HE11 mode conversion is achieved by inserting a circular dielectric rod (12) into a flared end (11) of a smooth-walled cylindrical feedhorn until a small cylindrical section of the dielectric rod engages with the inner wall (15) of the unflared portion of the feedhorn. In one feed arrangement, the other end of the dielectric rod is similarly inserted into a flared end (21) of a corrugated cylindrical feedhorn section (22) until a short longitudinal section of the cylindrical portion of the rod is concentric with the corrugations of an unflared section of the feedhorn to provide a transition for the HE11 mode into the corrugated waveguide for subsequent launch. In a second feed arrangement, the dielectric rod at the aperture of the smooth-walled flared feedhorn is flared outward to end in a curved configuration which is shaped to minimize reflections back into the dielectric rod and provide a predetermined wavefront at the aperture of the feed.

Wide bandwidth hybrid mode feeds

An antenna assembly which comprises a first laminar structure which includes a sheet of dielectric material having on one side a contiguous metal sheet and on the other side a strip transmission line adapted to be coupled with signal feeding means, and a second laminar structure, one side of which is in contact with the transmission line, and having on the other side, at least one region but preferable at least two concentrically arranged regions of a coated or cladded metal which serves as a radiator, characterized in that the transmission line is non-symetrically disposed with respect to the radiator.

Broadband microstrip antenna

A control system for allowing access to the use of home automation devices. The control system can include at least one home automation device. A biometric scanner can gather biometric data from a user. An automation controller can be in networked communication with the home automation device and the biometric scanner. The receive controller can process biometric data from the biometric scanner to enable access to the at least one home automation device.

Home automation security system and method

A microstrip antenna design according to which the impedance matching transformer is contained in the area usually occupied entirely by the etched metal radiator.

Loaded microstrip antenna with integral transformer

A microstrip antenna is disclosed having an etched metal radiator element including a polarizing patch consisting of a two dimensional removal of metallization from the central portion of the radiator element with one dimension of the polarization patch being greater than the other dimension e.g. an elongated rectangle and selectively oriented with respect to the input axis whereby, for example, circular polarization is achieved by means of orienting the polarization patch substantially 45° with respect to the input axis.

Microstrip antenna with circular polarization

A microstrip antenna design according to which a plurality of resonant frencies can be obtained for a given size radiator, to increase the usefulness of the antenna by providing for frequency diversity operation and by making the microstrip antenna tunable over a range of frequencies. As will be seen, the microstrip antenna is provided with an output termination which can be open-circuited or short-circuited, and at varying lengths, to change the frequency at which the microstrip antenna can be made resonant.

Terminated microstrip antenna

A broad band corrugated horn antenna with a double-ridged circular wavegu feed is disclosed in which the horn is driven by the wide band signal source having a bandwidth greater than 2:1. The bandwidth is accomplished by providing a ridge pattern with gaps therebetween in which the width of the gaps is greater than the width of the ridges.

Broadband corrugated horn with double-ridged circular waveguide

A microstrip antenna design according to which the resonant frequency can substantially reduced for a given size radiator, or to which the size of the radiator can be reduced for a given resonant frequency. As will be seen, a microstrip antenna loading is accomplished through the removal of a central portion of the etched metal radiator, and the amount of loading is a function of the size of the central portion removed.

John L. Kerr

Papers

Loaded microstrip antenna with integral transformer

Microstrip antenna with circular polarization

Terminated microstrip antenna

Broadband corrugated horn with double-ridged circular waveguide

Loaded microstrip antenna