| 摘要 |
PROBLEM TO BE SOLVED: To suppress dispersion of a resonance frequency to be minimum by making arithmetic average roughness (Ra) on the surface of a dielectric ceramic board forming a small planar patch antenna to be not more than a specified value and making water absorption of the dielectric ceramic board to be not more than the specified value. SOLUTION: A radiation electrode 3 is formed on one face of a dielectric ceramic board 2 of a Mg-Ca-Ti system or a Mg-La-Ca-Ti system, and an installed conductor 4 is formed on the other face so as to constitute a planar patch antenna 1. A power feeding pin is jointed to a power feeding point 5 of the radiation electrode 3 by solder and is extended to the side of an installed conductor 4, and it is connected to a coaxial cable. Radio waves transmitted from a GPS satellite are received by the radiation electrode 3 and it is transmitted to the coaxial cable via the power feeding pin. Arithmetic average roughness (Ra) on the surface of a porcelain on the dielectric ceramic board 2 is set not more than 1μm and the water absorption of the dielectric ceramic board 2 to be not more than 0.08%. Thus, a highly reliable and small planar patch antenna 1 can be obtained.
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