An antenna which reduces the number of end faces and perpendicular corners, and suffers from little deterioration of performance even if used for high frequency transmission/reception, in particular a microstrip patch antenna which is comprised of a dielectric substrate on the bottom surface of which a conductive ground plate is formed and on the top surface of which a patch antenna part formed by a conductor and a feeder circuit connected to the same are provided, wherein the feeder circuit is connected to the antenna part while offset by exactly a predetermined distance to either end side from a center of one side of said antennas part to which said feeder circuit is to be connected so that a transmission loss of the antenna becomes a predetermined value or less. The predetermined distance can be made 20 to 70% of the longitudinal side of the patch antenna part.
1. A transmission/reception antenna which is provided with:
a dielectric substrate on a bottom surface of which a conductive ground plate is formed; and
a plurality of independent antennas formed by a conductor and arranged on a top surface of the dielectric substrate in parallel;
each of the plurality of antennas comprising:
a feeder terminal; and
two microstrip antennas, each point symmetrically connected to the feeder terminal on opposite sides of the feeder terminal and each extending from the feeder terminal in a direction perpendicular to a direction on which feeder terminals of the plurality of antennas are arranged on the top surface of the dielectric substrate,
wherein for each of the plurality of antennas the feeder terminal thereof is not connected to the feeder terminal of any other of the plurality of antennas on the dielectric substrate, and
wherein each
microstrip antenna comprises:
a rectangular shaped antenna part;
a feeder strip line provided with an input end and a terminal end, whose terminal end is connected inclined by 45 degrees to either the left or right to one side of the antenna part to which the feeder strip line is connected while offset to either end side by a predetermined distance; and
a plurality of rectangular shaped microstrip patch antenna elements connected to at least one side of the feeder strip line, at their corners at predetermined intervals.
2. The transmission/reception antenna according to claim 1 , wherein
the predetermined distance is in a range of 0.2 to 0.7 units when distances to the two ends from a center of one side of the antenna part to which the feeder strip line is to be connected are “1” unit;
a length of the antenna part in a direction perpendicular to the polarization direction is a whole multiple of a guide wavelength by which an operating frequency of a wave received by the antenna is protected;
a length of the antenna part in a polarization direction is a whole multiple of half of the guide wavelength; and
connecting intervals of the microstrip antenna elements at one side of each feeder strip line are the distance of the guide wavelength.