Nippon Telegraph and Telephone Corporation

Yohei Toriumi

Jun Kato

Go Itami

Ken Okamoto

Tatsuya Iizuka

Fumihiko Ishiyama

A radar apparatus of the present embodiment includes a transmitting unit that transmits a frequency chirp signal whose frequency linearly changes with time, a receiving unit that receives a reflected wave that is the frequency chirp signal reflected by an object, a mixer that mixes the transmitted frequency chirp signal and the received reflected wave to obtain a beat signal, a frequency estimation unit that estimates a frequency of the beat signal, and a distance estimation unit that estimates a distance to the object based on the frequency of the beat signal. The frequency estimation unit calculates an autoregressive coefficient of an autoregressive model from a sequence of discrete signal values of the beat signal and estimates the frequency of the beat signal using a base frequency that is based on a pole of the autoregressive model.

Radar apparatus and distance measurement method

An electromagnetic field band-stop filter includes a plurality of unit structures that have reflection characteristics on an electromagnetic wave of a predetermined frequency. Each of the plurality of unit structures includes: a plurality of electrode parts each of which is disposed along a side of a polygon in a non-contact manner with another electrode part; and a plurality of conductor parts which are provided for the plurality of electrode parts on a one-to-one basis and each of which has at least one bent portion between one end and other end, the one ends of the plurality of conductor parts being connected to the electrode parts on a one-to-one basis and the other ends of the plurality of conductor parts being connected at one point on an inner side of the electrode parts in the individual unit structure. The plurality of unit structures are regularly and two-dimensionally disposed by disposing electrode parts of the plurality of unit structures to be adjacent to each other with a spacing that reflects the predetermined frequency.

Electromagnetic field band-stop filter

A frequency selective surface having a steep attenuation slope (high sharpness) characteristic is provided without decreasing the line width of a conductive pattern nor the pattern interval thereof. In a frequency selective surface having a structure in which resonators kxy having identical shapes are periodically arrayed on a dielectric substrate, each resonator kxy includes a cross-shaped conductive pattern formed on the dielectric substrateand a lateral patternand a longitudinal patternforming a cross are shaped such that each pattern is extended by a predetermined length in respective directions, each pattern extended by the predetermined length is further extended in both directions orthogonal to each other on the dielectric substrate, and leading end parts of the respective further extensions face each other at a predetermined interval d.

Frequency selective surface

To provide a frequency selective surface of which an operating frequency and a bandwidth thereof can be readily adjusted. A frequency selective surface structured such that resonators kformed by conductive patterns with a same shape are periodically arranged on a dielectric substrate, wherein the resonator kincludes: a conductor wire part with a lateral patternand a longitudinal patternwhich form a cross above a dielectric substrate; and an electrode plate part created by extending, in directions in which the lateral pattern and the longitudinal pattern are orthogonal to each other, respective both end parts of the lateral pattern and the longitudinal pattern having been extended by a prescribed length, the electrode plate part being shaped such that a tip portion thereof opposes a tip portion extended from another direction at an interval above a diagonal line, and the electrode plate part is shaped such that a central portion opposing an electrode plate part of another adjacent resonator is notched in a width of the lateral pattern, the electrode plate part being joined with the electrode plate part of the other adjacent resonator by being extended from a center of the notched portion in a width that is narrower than the width of the lateral patternand in a length that is shorter than the prescribed length, and the interval of the tip portion is wider than an interval with the electrode plate part of the other adjacent resonator.

To accurately estimate frequency characteristics from structural parameters of a frequency selective surface. A frequency selective surface design apparatus includes an LC generation unitthat receives an input of a structural parameter, and generates an inductance L and a capacitance C of a unit cell, a corrected resonance point calculation unitthat receives the number n of times of calculation input from an outside, the inductance L, and the capacitance C, models a correction circuit by using a circuit in which a virtual capacitance is connected in parallel via a transmission line to each distribution inductance obtained by division of the inductance L by the calculation number n and the transmission line is terminated at the capacitance C, and calculates a corrected resonant frequency fC from the impedance of the correction circuit, and a characteristic calculation unitthat receives inputs of the inductance L, the capacitance C, and the corrected resonant frequency fC, calculates a pre-correction resonant frequency from the inductance L and the capacitance C, obtains a correction coefficient by dividing the corrected resonant frequency fC by the pre-correction resonant frequency, and calculates a corrected return loss and a corrected insertion loss.

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Tokyo, Japan

Yohei Toriumi