An overview of analog microwave photonics will be presented. The performance requirements for externally-modulated analog microwave photonic links will be reviewed with specific emphasis placed on modulator efficiency, laser noise, detected photocurrent, and link linearity.

http://ieeexplore.ieee.org/iel5/6387506/6403300/06403360.pdf

Microwave photonics

Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, a mushroom-like EBG structure is analyzed using the finite-difference time-domain (FDTD) method. Its band-gap feature of surface-wave suppression is demonstrated by exhibiting the near field distributions of the electromagnetic waves. The mutual coupling of microstrip antennas is parametrically investigated, including both the E and H coupling directions, different substrate thickness, and various dielectric constants. It is observed that the E-plane coupled microstrip antenna array on a thick and high permittivity substrate has a strong mutual coupling due to the pronounced surface waves. Therefore, an EBG structure is inserted between array elements to reduce the mutual coupling. This idea has been verified by both the FDTD simulations and experimental results. As a result, a significant 8 dB mutual coupling reduction is noticed from the measurements.

/pdf/microstrip-antennas-integrated-with-electromagnetic-band-gap-1t2jb53z58.pdf

Microstrip antennas integrated with electromagnetic band-gap (EBG) structures: a low mutual coupling design for array applications

This chapter contains sections titled: Overview MAC convergence sublayer MAC common part sublayer MAC security sublayer MAC enhancements for 2-11 GHz operation IEEE 802.16 physical layers Coexistence BWA business and technology trends

Air Interface for Fixed Broadband Wireless Access Systems

MEMS switches are devices that use mechanical movement to achieve a short circuit or an open circuit in the RF transmission line. RF MEMS switches are the specific micromechanical switches that are designed to operate at RF-to-millimeter-wave frequencies (0.1 to 100 GHz). The forces required for the mechanical movement can be obtained using electrostatic, magnetostatic, piezoelectric, or thermal designs. To date, only electrostatic-type switches have been demonstrated at 0.1-100 GHz with high reliability (100 million to 10 billion cycles) and wafer-scale manufacturing techniques. It is for this reason that this article will concentrate on electrostatic switches.

RF MEMS switches and switch circuits

Metasurfaces: From microwaves to visible

By covering a metal ground plane with a periodic surface texture, we can alter its electromagnetic properties. The impedance of this metasurface can be modeled as a parallel resonant circuit, with sheet inductance L, and sheet capacitance C. The reflection phase varies with frequency from +/spl pi/ to -/spl pi/, and crosses through 0 at the LC resonance frequency, where the surface behaves as an artificial magnetic conductor. By incorporating varactor diodes into the texture, we have built a tunable impedance surface, in which an applied bias voltage controls the resonance frequency, and the reflection phase. We can program the surface to create a tunable phase gradient, which can electronically steer a reflected beam over +/- 40/spl deg/ in two dimensions, for both polarizations. We have also found that this type of resonant surface texture can provide greater bandwidth than conventional reflectarray structures. This new electronically steerable reflector offers a low-cost alternative to a conventional phased array.

Two-dimensional beam steering using an electrically tunable impedance surface

An element card for an ultra-wideband array antenna is disclosed. The element card has one or more integrated antennas and can be designed to operate over multiple decades of bandwidth. The element card may be arranged as part of an array of element cards to achieve operation in multiple frequency bands.

Integrated ultra wideband element card for array antennas

Intermodulation and harmonic distortion are calculated for a simple fiber-optic link with a representative set of link parameters and a variety of electrooptic modulators: simple Mach-Zehnder, linearized dual and triple Mach-Zehnder, simple directional coupler (two operating points), and linearized directional coupler with one and two dc electrodes. The resulting dynamic ranges, gains, and noise figures are compared for these modulators. A new definition of dynamic range is proposed to accommodate the more complicated variation of intermodulation with input power exhibited by linearized modulators. The effects of noise bandwidth, preamplifier distortion, and errors in modulator operating conditions are described. >

/pdf/distortion-in-linearized-electrooptic-modulators-3sngj7712c.pdf

Distortion in linearized electrooptic modulators

Low cost millimeter wave imagers using two-dimensional focal plane arrays based on backward tunneling diode (BTD) detectors. Two-dimensional focal arrays of BTD detectors are used as focal plane arrays in imagers. High responsivity of BTD detectors near zero bias results in low noise detectors that alleviate the need for expensive and heat generating low noise amplifiers or Dicke switches in the imager. BTD detectors are installed on a printed circuit board using flip chip packaging technology and horn antennas direct the waves toward the flip chip including the BTD detectors. The assembly of the horn antennas, flip chips, printed circuit board substrate, and interconnects together work as an imaging sensor. Corrugated surfaces of the components prevent re-radiation of the incident waves.

Low cost millimeter wave imager

A method of and apparatus for modulating an optical carrier by an incident electromagnetic field. The electromagnetic field propagates in a dielectric-filled transverse electromagnetic waveguide, At least one slice of an electro-optic material is disposed in the dielectric-filled transverse electromagnetic waveguide, the electro-optic material in the dielectric-filled transverse electromagnetic waveguide having at least one optical waveguide therein which has at least a major portion thereof guiding light in a direction orthogonal with respect to a direction in which the dielectric-filled transverse electromagnetic waveguide guides the incident electromagnetic field. Light is caused to propagate in the at least one optical waveguide in the at least one slice of an electro-optic material in the dielectric-filled transverse electromagnetic waveguide for modulation by the incident electromagnetic field.

James H. Schaffner

Papers

Two-dimensional beam steering using an electrically tunable impedance surface

Integrated ultra wideband element card for array antennas

Distortion in linearized electrooptic modulators

Low cost millimeter wave imager

Microwave receiver front-end assembly and array