Abstract: An artificial magnetic conductor is resonant at multiple resonance frequencies. The artificial magnetic conductor is characterized by an effective media model which includes a first layer and a second layer. Each layer has a layer tensor permittivity and a layer tensor permeability having non-zero elements on the main tensor diagonal only.

Abstract: A low profile antenna system includes an artificial magnetic conductor comprising a frequency selective surface (FSS) having an effective sheet capacitance which is electronically variable to control resonant frequency of the AMC and the resonant frequency of an antenna element positioned adjacent to the FSS.

Abstract: An artificial anisotropic dielectric material can be used as a microstrip patch antenna substrate. The artificial dielectric can be easily designed for the purpose of weight reduction. Preferably, the artificial dielectric is comprised of a periodic stack of low and high permittivity layers. The layers can be oriented vertically below the patch to support electric fields consistent with desired resonant modes. Substrates may be engineered for both linearly and circularly polarized patch antennas. Antenna weight can be reduced to ⅙th up to {fraction (1/30)}th of the original weight using different types of high permittivity layers. This concept has numerous applications in electrically small and lightweight antenna elements such as PIFA antennas. In accordance with one aspect of the invention, the artificial dielectric is comprised of an interlocking structure of low and high permittivity layers for ease of assembly and for overall stability.

Abstract: DC inductive FSS technology is a printed slow wave structure usable for reduced size resonators in antenna and filter applications of wireless applications. It is a dispersive surface defined in terms of its parallel LC equivalent circuit that enhances the inductance and capacitance of the equivalent circuit to obtain a pole frequency as low as 300 MHz. The effective sheet impedance model has a resonant pole whose free-space wavelength can be greater than 10 times the FSS period. A conductor-backed DCL FSS can create a DC inductive artificial magnetic conductor (DCL AMC), high-impedance surface with resonant frequencies as low as 2 GHz. Lorentz poles introduced into the DCL FSS create multi-resonant DCL AMCs. Antennas fabricated from DCL FSS materials include single-band elements such as a bent-wire monopole on the DCL AMC and multi-band (dual and triple) shorted patches, similar to PIFAs with the patch/lid being a DCL FSS.

Abstract: In an artificial magnetic conductor, the distance between the frequency selective surface and the ground plane is mechanically varied to adjust the effective inductance or capacitance of the structure and thus the resonant frequency of the device.

Abstract: An antenna system includes a beamformer having a feed port and a one-dimensional or two-dimensional arrangement of output ports, radiating antenna elements coupled with output ports of the beamformer, and an antenna control unit coupled with the beamformer to steer a beam of the antenna system. The antenna system forms an electrically steerable, phased array antenna having a beam steering angle which is constant over a very broad band of frequencies. Specific applications for the antenna system include satellite communications including tracking low earth orbiting satellites, radar systems and data links using a steerable antenna for self-installation, self-healing and adaptation.

Abstract: A frequency reconfigurable artificial magnetic conductor (AMC) includes a ground plane, a spacer layer disposed adjacent the ground plane and a plurality of vias in electrical contact with the ground plane and extending from a surface of the ground plane in direction of the spacer layer. The AMC further includes a frequency selective surface (FSS) disposed on the spacer layer and including a periodic pattern of bias node patches alternating with ground node patches, the ground node patches being in electrical contact with respective vias of the plurality of vias, and components between selected bias node patches and ground node patches, the components having a capacitance which is variable in response to a bias voltage. A network of bias resistors between adjacent bias node patches provides the tuning voltage.

Abstract: In a planar inverted F antenna (PIFA), the feed and RF grounding connections are reversed yielding improved performance. Relative positioning of these connections is selected to tailor the characteristics of the antenna, such as resonant frequency and impedance bandwidth.

Abstract: An artificial anisotropic dielectric material can be used as a microstrip patch antenna substrate. The artificial dielectric can be easily designed for the purpose of weight reduction. Preferably, the artificial dielectric is comprised of a periodic stack of low and high permittivity layers. The layers can be oriented vertically below the patch to support electric fields consistent with desired resonant modes. Substrates may be engineered for both linearly and circularly polarized patch antennas. Antenna weight can be reduced to ⅙th up to {fraction (1/30)}th of the original weight using different types of high permittivity layers. This concept has numerous applications in electrically small and lightweight antenna elements such as PIFA antennas. In accordance with one aspect of the invention, the artificial dielectric is comprised of an interlocking structure of low and high permittivity layers for ease of assembly and for overall stability.

Abstract: An artificial magnetic conductor is resonant at multiple resonance frequencies. The artificial magnetic conductor is characterized by an effective media model which includes a first layer and a second layer. Each layer has a layer tensor permittivity and a layer tensor permeability having non-zero elements on the main tensor diagonal only.

Abstract: A microstrip trombone delay line is used to provide a low cost true time delay device. An array of printed trombone lines arranged in a network is used to implement a linear beamformer. The beamformer forms an array that scans signals in one or more dimensions. Each microstrip trombone delay line includes printed traces on a fixed substrate and a printed trombone line on a movable superstrate. The microstrip trombone delay line may have different dimensions to vary the characteristic impendence at either end for impedance matching purposes. Beamformers using microstrip trombone delay lines and scanning in multiple principal planes require few movable parts and only linear actuators.

Abstract: An antenna comprises a conductive member having an opening for radiating an electromagnetic signal. A circuit board is spaced apart from the conductive member by less than one-quarter wavelength of the electromagnetic signal. The circuit board has a series of conductive cells for suppressing at least one propagation mode propagating between the conductive member and circuit board over a frequency bandwidth range defined by a geometric arrangement of the conductive cells.

Abstract: A patch antenna is composed of a segmented patch and MEMS switches which are built on a substrate. The patch segments of the segmented patch can be electrically connected to each other by the MEMS switches to form a contiguous patch and optional tuning strips and to connect or block RF between the contiguous patch and the optional tuning strips. When RF is connected between the tuning strips and the contiguous patch, the tuning strips increase the effective length of the contiguous patch and lower the antenna's resonant frequency, thereby allowing the antenna to be frequency tuned electrically over a relatively broadband of frequencies. When the tuning strips are connected to the patch in other than a symmetrical pattern, the antenna pattern of the antenna can be changed. In another aspect of the invention, the optional tuning strips are continuous structures that are formed by connecting patch segments using switches.

Abstract: The present invention relates generally to radio communication devices. More particularly, the present invention relates to a programmable radio frequency (RF) sub-system and wireless communications devices using such an integrated antenna/filter sub-system. In one embodiment, the programmable RF front end subassembly includes two antennas, RF filter sections that are integral to each antenna, and a programmable logic device as an antenna control unit. Each antenna consists of a planar inverted “F” antenna (PIFA) that is tuned to operate over a range of frequencies using voltage variable capacitors or RF switches that connect various capacitive loads in order to achieve the desired resonant frequencies. The wireless communication device further includes a control circuit coupled to the antenna to provide the control signals.

Abstract: An antenna beamformer is disclosed that uses controllable time delay elements distributed in a planar fractal feed network between the input port and multiple output ports. The use of time delay elements, rather than phase shifting elements, allows the beamformer to maintain a constant steering angle independent of frequencies over a broad range of frequencies. In addition, fewer control signals are used to control all of the time delay elements due to distributing the time delay elements throughout the fractal feed network, rather than grouping the delay elements near the output ports.

Abstract: A frequency reconfigurable artificial magnetic conductor (AMC) includes a ground plane, a spacer layer disposed adjacent the ground plane and a plurality of vias in electrical contact with the ground plane and extending from a surface of the ground plane in direction of the spacer layer. The AMC further includes a frequency selective surface (FSS) disposed on the spacer layer and including a periodic pattern of bias node patches alternating with ground node patches, the ground node patches being in electrical contact with respective vias of the plurality of vias, and components between selected bias node patches and ground node patches, the components having a capacitance which is variable in response to a bias voltage. A network of bias resistors between adjacent bias node patches provides the tuning voltage.

Abstract: An electronically reconfigurable artificial magnetic conductor (RAMC) includes a frequency selective surface (FSS) having an effective sheet capacitance which is variable to control resonant frequency of the RAMC. In one embodiment, the RAMC further includes a conductive backplane structure and a spacer layer separating the conductive backplane structure and the FSS. The spacer layer includes conductive vias extending between the conductive backplane structure and the FSS, and voltage variable capacitive circuit elements coupled with the FSS and responsive to bias voltages applied on one or more bias signal lines routed through the conductive backplane structure and the conductive vias.

Abstract: A bandpass radome that reduces the number of spurious resonances, and that tends to suppress Transverse Magnetic TM and Transverse Electric TE surface waves, is described. In one embodiment, the radome includes an inductive FSS ground plane layer. First and second capacitive FSS layers are disposed above the inductive ground plane layer. Third and fourth capacitive FSS layers are disposed below the inductive ground plane layer. In one embodiment, the capacitive FSS layers use patch elements and some or all of the FSS patch elements above and below the inductive ground plane layer are electrically connected to the inductive ground plane layer by a conducting posts. The conducting posts form a rodded medium to suppress TM and TE surface waves. In one embodiment the total thickness of the bandpass radome is less than &lgr;/20 at the center frequency of the passband.

Abstract: A tunable artificial dielectric material achieves the weight reductions made possible in U.S. Pat. No. 6,075,485 and further achieves even higher resonant frequency tuning ratios. In one embodiment of the invention, the artificial dielectric substrate for a patch antenna comprises alternating low and high permittivity layers, with the high permittivity layers each comprised of printed capacitive Frequency Selective Surface (FSS). An example FSS of the invention has a voltage tunable effective sheet capacitance by virtue of varactor diodes integrated into each unit cell. By appropriate adjustment of the bias voltage across the varactor diodes, the amount of the electric field stored in the substrate can be varied, which further varies the resonant frequency of the patch antenna.

Abstract: An artificial anisotropic dielectric material is used as a microstrip patch antenna substrate and can achieve dramatic antenna weight reduction. The artificial dielectric is comprised of a periodic structure of low and high permittivity layers. The net effective dielectric constant in the plane parallel to the layers is engineered to be any desired value between the permittivities of the constituent layers. These layers are oriented vertically below the patch to support electric fields consistent with desired resonant modes. Substrates may be engineered for both linearly and circularly polarized patch antennas. Substrate weights can be reduced by factors of from 6 to 30 times using different types of high permittivity layers. This concept has numerous applications in electrically small and lightweight antenna elements, as well as in resonators, microwave lenses, and other electromagnetic devices.