Patent
Varactor tuned helical resonator for use with duplex filter
TLDR
In this article, a radio frequency filter comprising several resonator circuits, such as duplex filter, is provided with a given passband, where signal frequencies generating spurious response, mirror frequencies, etc. can be effectively attenuated so that the filter comprises one more resonator circuit connected as a bandstop circuit.Abstract:
A radio frequency filter comprising several resonator circuits, such as duplex filter, is provides with a given passband. Signal frequencies generating spurious response, mirror frequencies, etc. can be effectively attenuated so that the filter comprises one more resonator circuit connected as a bandstop circuit. That comprises a transmission line resonator (Res), a series connection of an inductive element (MLIN2) and a capacitance diode (D), one end of the series connection being couples to a coupling point in the transmission line resonator, dividing it into two parts (TLIN1, TLIN2), and the other end being couples to the output connector (1) of the radio frequency filter. In addition, means are provided for carrying the direct voltage (V+) to the cathode of the capacitance diode, whereby the series resonance frequency changes according to the control voltage.read more
Citations
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Patent
Method of channel frequency allocation for rf and microwave duplexers
Xiao-Peng Liang,John Robinson +1 more
TL;DR: In this article, a method for operating a duplexer including a first tunable bandpass filter, a second tunable BS filter and a second BS filter is presented. But the method is not suitable for duplexing in the presence of a single antenna.
Patent
Chassis-excited antenna apparatus and methods
TL;DR: In this article, a distributed loop antenna configuration is used within a handheld mobile device (e.g., cellular telephone), where the antenna comprises two radiating elements: one configured to operate in a high frequency band and the other in a low frequency band.
Patent
Adjustable multi-band antenna and methods
TL;DR: An adjustable multi-band planar antenna especially applicable in mobile terminals is discussed in this article, where the feed of the antenna is connected by a multiple-way switch to at least two alternative points of the radiator element.
Patent
Antenna, component and methods
TL;DR: In this article, an antenna component and antenna component with a dielectric substrate and a plurality of radiating antenna elements on the surface of the substrate is presented, where the lower edge of one of the antenna elements is galvanically coupled to the antenna feed conductor on a circuit board, and at another point to the ground plane.
Patent
Adjustable multiband antenna and methods
TL;DR: An adjustable multi-band planar antenna especially applicable in mobile terminals and a radio device was proposed in this paper. But it was not shown that the antenna can adjust the positions of at least two operating bands.
References
More filters
Patent
Filter with electrically adjustable attenuation characteristic
TL;DR: A tunable bandstop/bandpass filter, particularly suitable for use in duplex applications where the transmit and receive bands are closely located, comprises two or more reactively coupled quarter wavelength resonators e.g. dielectric resonators.
Patent
Circuit for coupling radio receiver and radio transmitter to a common antenna for duplex operation
TL;DR: In this article, an antenna coupling circuit for duplex radio transmission and reception by use of a common antenna (duplexer), including plurality of helical resonator sections provided within conductive enclosures in a conductive housing, is described.
Patent
Tunable notch filter for image frequency and conducted local oscillator leakage rejection
TL;DR: In this article, a tunable notch filter for the front end of an RF receiver includes magnetically coupled input and output tunable stages each responsive to a tuning voltage provided by the receiver.
Patent
Electronically tunable band reject filter
TL;DR: In this paper, an electronically tunable band reject filter is proposed to reject only frequencies of a signal that are in the reject band around its center frequency, where an output directional coupler combines the second signal with the filtered signal.
Patent
Varactor tunable coupled transmission line band reject filter
TL;DR: In this article, a D.C. bias voltage across the varactor diodes controls the center frequency of the resulting notch filter, which is used in the microwave frequency range.