Patent ID: 6985114

Claim:
A constituting method of a multi-frequency antenna for transmitting and receiving electric waves having the wavelengths of λ a and λ b , the method comprising; setting an orthogonal coordinate X, Y, making the lengthwise direction of a first antenna element ( 21 ) having an electric length of λ a /4 in parallel to the X axis, positioning and arranging one edge in the lengthwise direction of said first antenna element ( 21 ) near the Y axis, making the lengthwise direction of a second antenna element ( 22 ) having an electric length of λ b /4 in parallel to the X axis, positioning and arranging one edge in the lengthwise direction of said second antenna element ( 22 ) near the Y axis, connecting electrically a point ( 0 ), where an impedance is 0 , at the one edge of each of said two antenna elements with a short-circuit line ( 4 ) along the Y axis, connecting electrically said short-circuit line ( 4 ) with a ground plate ( 8 ), making a point of impedance being 50 Ω ( 50 ) of each of said two antenna elements to be a power feed point, and connecting electrically a center conductor ( 7 a ) of a coaxial cable ( 7 ) with said power feed points, while an external conductor ( 7 b ) of the coaxial cable is grounded.