A waveguide (100) including at least one outer surface (105, 110, 115, 120) defining a waveguide cavity (140) and at least one inner surface (130, 135) positioned within the waveguide cavity (140). The inner surface (130, 135) includes a frequency selective surface (FSS) having a plurality of FSS elements (145) coupled to at least one substrate. The substrate defines a first propagation medium such that an RF signal having a first wavelength in the first propagation medium can pass through the FSS (130, 135). The FSS (130, 135) is coupled to a second propagation medium such that in the second propagation medium the RF signal has a second wavelength which is at least twice as long as a physical distance between centers of adjacent FSS elements (145). The second wavelength can be different than the first wavelength.

Multi-band horn antenna using frequency selective surfaces

Method for forming a transformer (118) in a ceramic substrate. The method can include the steps of forming at least one conductive coil (119a, 119b) comprising a plurality of turns about an unfired ceramic toroidal core region (120a, 120b) defined within an unfired ceramic substrate (100). The method can also include the step of co-firing the unfired ceramic toroidal core region (120a, 120b), the unfired ceramic substrate (100), and the conductive coil (119a, 119b) to form an integral ceramic substrate structure with the conductive coil at least partially embedded therein.

Embedded toroidal transformers in ceramic substrates

A method for making an embedded toroidal inductor (118) includes forming in a ceramic substrate (100) a first plurality of conductive vias (102) radially spaced a first distance from a central axis (101) so as to define an inner circumference. A second plurality of conductive vias (104) is formed radially spaced a second distance about the central axis so as to define an outer circumference. A first plurality of conductive traces (110) forming an electrical connection between substantially adjacent ones of the first and second plurality of conductive vias is formed on a first surface (106) of the ceramic substrate. Further, a second plurality of conductive traces (110) forming an electrical connection between circumferentially offset ones of the first and second plurality of conductive vias is formed on a second surface of the ceramic substrate opposed from the first surface to define a three dimensional toroidal coil.

Embedded toroidal inductors

An antenna (100) includes at least one antenna radiating element (108, 110) and a dielectric structure (102) defining a cavity containing a fluid dielectric (106). The dielectric structure (102) can be a dielectric circuit board substrate with a ground plane (116) provided opposed to the antenna radiating elements (108, 110). The fluid dielectric (106) is electrically and magnetically coupled to the antenna radiating element. Further, a composition processor (301) is provided for selectively varying a composition of the fluid dielectric (106) so as to dynamically change an electrical characteristic of the antenna radiating element (108) in response to a control signal.

Antenna with dynamically variable operating band

A crossed slot fed microstrip antenna (100). The antenna (100) includes a conducting ground plane (125), which has at least one crossed slot (125), and at least two feed lines (105). The feed lines (105) have respective stub regions (115) that extend beyond the crossed slot (125) and transfer signal energy to or from the crossed slot (125). The antenna (100) also includes a first substrate (150) disposed between the ground plane (120) and the feed lines (105). The first substrate (150) includes a first region and at least a second region, the regions having different substrate properties. The first region is proximate to at least one of the feed lines (105).

High efficiency crossed slot microstrip antenna

This article deals with a new generation of tunable microwave devices using ferromagnetic materials. The sensitivity of the device cut-off frequency to the dc magnetic field was investigated for two filtering resonators (stub resonator and Stepped Impedance Resonator). The stub resonator exhibited a frequency tunability of nearly 40% for a dc magnetic field strength of 250 Oe, whereas the linewidth remained unchanged. A 12.2% tunability of the SIR device was reached under 250 Oe applied.

Ferromagnetic composite-based and magnetically-tunable microwave devices

This paper deals with the design of magnetic tunable microwave filtering functions based on the use of ferromagnetic composites embedded in a polymer substrate of a microstrip transmission line. Our investigation focussed on the relevant design parameters of the composite-loaded microstrip structure to determine its best geometrical parameters in order to increase the device tunability. This analysis was exploited to work out two-stepped impedance filters. The first of them is a single resonator. Its measured scattering parameters evidence a 12 % tenability under a 250-G applied bias field. Through the second-order filter is still under achievement, simulation data let us expect far much lower insertion losses and better performances.

P. Queffelec

Papers

Ferromagnetic composite-based and magnetically-tunable microwave devices

Enhancement of design parameters for tunable ferromagnetic composite-based microwave devices: application to filtering devices