Methods and apparatus for providing a frequency selective limiters (FSL) having a free-standing Yttrium Iron Garnet (YIG) film with first and second opposing surfaces. A metal plane is disposed on one surface of the YIG film to provide the YIG film with a metalized surface. At least one transducer is disposed on the other surface of the YIG film with a respective ends coupled to the metalized surface of the YIG film.

Described is a frequency selective limiter (FSL) module comprising a cascade of an FSL and a functional limiter (e.g. a conventional semiconductor limiter comprising a PIN diode) with steady state limiting and power threshold values selected such the FSL module provides suppression of a spike leakage power and while still enabling frequency selective limiting.

A directional coupler includes an input connector, an output connector, and at least one tap connector. The directional coupler also includes a primary line connecting the input connector to the output connector and configured to carry an RF signal and an AC signal, and a secondary line connecting the primary line to the at least one tap connector and configured to carry a split off portion of the RF signal. The directional coupler also includes a tapped line circuit which is inhibited from carrying the AC signal. The mainline transformer includes a ferrite element surrounding the primary line and which is split in at least one location to include a gap of non-magnetic material that inhibits saturation of the ferrite element.

A wireless communication system including an electrically conductive passive medium capable of simultaneously propagating therealong electromagnetic first and second currents at different respective frequencies F1 and F2, the electrically conductive passive medium including an electrically conductive first passive linear medium portion adjacent an electrically conductive first passive nonlinear medium portion, the first passive nonlinear medium portion capable of generating an intermodulation current based on a nonlinear interaction between the first and second currents, the intermodulation current having a frequency Fi equal to nF1+mF2 and propagating along the first passive nonlinear medium portion, m and n being positive or negative integers; and a first magnetic film disposed proximate an electrically conductive external surface of the first linear medium portion, such that when the first and second currents propagate along the first passive linear medium portion toward the first passive nonlinear medium portion, the magnetic film reduces or prevents the generation of the intermodulation current in the first passive nonlinear medium portion by attenuating at least portions of the first and second currents.

A wireless communication system including an electrically conductive passive medium capable of simultaneously propagating therealong electromagnetic first and second currents at different respective frequencies F1 and F2, the electrically conductive passive medium including an electrically conductive first passive linear medium portion adjacent an electrically conductive first passive nonlinear medium portion, the first passive nonlinear medium portion capable of generating an intermodulation current based on a nonlinear interaction between the first and second currents, the intermodulation current having a frequency Fi equal to nF1+mF2 and propagating along the first passive nonlinear medium portion, m and n being positive or negative integers; and a first magnetic film disposed proximate an electrically conductive external surface of the first linear medium portion, such that when the first and second currents propagate along the first passive linear medium portion toward the first passive nonlinear medium portion, the magnetic film reduces or prevents the generation of the intermodulation current in the first passive nonlinear medium portion by attenuating at least portions of the first and second currents.

A tunable frequency selective limiter is disclosed. In one or more embodiments, the tunable frequency selective limiter includes a first electrically conductive path. The tunable frequency selective limiter also includes a ferrimagnetic layer disposed adjacent to the first electrically conductive path. The tunable frequency selective limiter further includes a second electrically conductive path coiled around the first electrically conductive path and the ferrimagnetic layer. An electromagnetic current transmitting through the second electrically conductive path produces a magnetic field coupled to the ferrimagnetic layer. The tunable frequency selective limiter further includes a dielectric layer, wherein the ferrimagnetic layer is disposed on the dielectric layer. The portions of the second electrically conductive path that are at the interface of the dielectric layer and the ferrimagnetic layer may be embedded into the dielectric layer or may be disposed on the surface of the dielectric layer.

A tunable frequency selective limiter is disclosed. In one or more embodiments, the tunable frequency selective limiter includes a first electrically conductive path. The tunable frequency selective limiter also includes a ferrimagnetic layer disposed adjacent to the first electrically conductive path. The tunable frequency selective limiter further includes a second electrically conductive path coiled around the first electrically conductive path and the ferrimagnetic layer. An electromagnetic current transmitting through the second electrically conductive path produces a magnetic field coupled to the ferrimagnetic layer. The tunable frequency selective limiter further includes a dielectric layer, wherein the ferrimagnetic layer is disposed on the dielectric layer. The portions of the second electrically conductive path that are at the interface of the dielectric layer and the ferrimagnetic layer may be embedded into the dielectric layer or may be disposed on the surface of the dielectric layer.

A wireless communication system includes a transmitter configured to transmit at least first and second radio waves having respective different frequencies F1 and F2, an electrically conductive first passive substantially linear medium, an electrically conductive first passive substantially nonlinear medium disposed proximate the first passive substantially linear medium, and a first magnetic film covering at least a portion of the first passive substantially linear medium. When the transmitter transmits the first and second radio waves, the first passive substantially linear and nonlinear media receive the first and second radio waves and generate first and second signals propagating therein at the respective frequencies F1 and F2. At least one intermodulation signal having a frequency F3 equal to nF1+mF2, where m and n positive or negative integers, is generated in the first passive substantially nonlinear medium. The first magnetic film reduces the at least one intermodulation signal by at least 2 dB.

A wireless communication system includes a transmitter configured to transmit at least first and second radio waves having respective different frequencies F1 and F2, an electrically conductive first passive substantially linear medium, an electrically conductive first passive substantially nonlinear medium disposed proximate the first passive substantially linear medium, and a first magnetic film covering at least a portion of the first passive substantially linear medium. When the transmitter transmits the first and second radio waves, the first passive substantially linear and nonlinear media receive the first and second radio waves and generate first and second signals propagating therein at the respective frequencies F1 and F2. At least one intermodulation signal having a frequency F3 equal to nF1+mF2, where m and n positive or negative integers, is generated in the first passive substantially nonlinear medium. The first magnetic film reduces the at least one intermodulation signal by at least 2 dB.

In an embodiment, a microwave circuit (circuit) includes an attenuator configured to attenuate a plurality of frequencies in a microwave signal. In an embodiment, the attenuator comprises a component of a first material, the first material exhibiting superconductivity in a cryogenic temperature range. In an embodiment, the circuit includes a magnet configured to generate a magnetic field at the attenuator, wherein the magnetic field is at least equal to a critical magnetic field strength of the first material. In an embodiment, the critical magnetic field strength causes the first material to become non-superconductive in the cryogenic temperature range.