Each house receiving device null for prevention of disasters radio system

摘要

PROBLEM TO BE SOLVED: To make the device low-priced by reducing the size of a rod antenna by connecting a radial and increasing the reception sensitivity of the rod antenna when electric field intensity is weak. SOLUTION: A device main body 1 consists of the rod antenna 11, a jack 12 for external antenna connection, a reception part which amplifies and demodulates the received signal from the antenna 11, a speaker 13 which reinforces the sound signal outputted by the reception part, etc. The radial 2 consists of a metallic round rod 21 of a radial main body which is connected to the jack 12 for an external antenna to increase the sensitivity of the rod antenna 11, and a pin plug 22. The device main body 1 receives a radio wave by using its internal rod antenna 11, but when the electric field intensity is weak, the radial 2 is connected to the external antenna jack 12. At this time, the pin plug 22 of the radial 2 is inserted into the external antenna jack 12 and connected. Thus, the radial 2 is added to the rod antenna 11 instead of a dipole antenna to improve the reception sensitivity of the rod antenna itself.