Nippon Telegraph and Telephone Corporation

Toyota Jidosha Kabushiki Kaisha

Junichi Kodate

Ai-ichiro Sasaki

Hiroki Okada

Jumpei Fuke

Hiroko Okuyama

Ai-Ichiro Sasaki

A dual loop antenna is provided which can clearly set a boundary of a communication area and create a well-balanced communication area. A dual loop antenna includes a first loop antenna and a second loop antenna. The first loop antenna and the second loop antenna are formed on an x-y plane. The center of the first loop antenna and the center of the second loop antenna are located at positions on an x-axis at the same distance from the point of origin being the center of the dual loop antenna. A phase difference between currents flowing on the first loop antenna and the second loop antenna, respectively, is a value in a range from 130 degrees to 230 degrees.

Dual loop antenna

Even when at least one of a capacitor (C) connected to a main loop and a capacitor (C) connected to an amplification loop cannot be set to an optimal value, a current value of a current (I) flowing on the amplification loop can be made sufficiently large by setting the capacitors (C, C) based on any of an optimal Ccurved line, an optimal Ccurved line, and an optimal Cstraight line that pass through an optimal point (C, C) of the capacitors (C, C) and extend along a ridge of contour lines each joining the points where the magnitude of the current (I) is equal on a diagram showing a relation of values of the capacitors (C, C) with the magnitude of the current (I).

Loop antenna and design method for loop antenna

In an antenna circuit including an antennaand an antennathat is connected in series with the antennaand includes inductance, a variable capacitor Cand a variable resistor Rconnected in parallel with the antennaare provided. This enables controlling of an actual amplitude ratio r and a phase difference &#x3b8; between currents Iand Iflowing through the two antennasandinto desired values. Flows of the currents Iand Iwith the phase difference &#x3b8; through the antennasandenable forming of a favorable communication area. In addition, setting of the actual amplitude ratio r between the currents Iand Iflowing through the antennasandto a value other than 1 enables forming of an asymmetric communication area.

Growing community of inventors

Atsugi, Japan

Junichi Kodate