| 摘要 |
PURPOSE:To improve the characteristic of band at shoulder and skirt and to suppress the out-band response by connecting the 2nd electrodes transmitting/ receiving an elastic surface wave with a weighted electrode being the 1st electrode in series or parallel mutually and forming the electrodes as a group of plural identical electrodes in a main lobe. CONSTITUTION:The 2nd electrodes A1, A2, B1, B2 are formed as an electrode group where NA-set of small pair number (m) of normal electrodes is arranged so that the interval between the centers of adjacent electrodes is constant (DELTAxA) on the same transmission line, electrical outputs of each electrode are extracted while being connected in series or parallel, and a periodical peak or a trap is formed on the frequency axis by adding electric outputs of each electrode whose phase is changed sequentially with an equal difference so as to interfere with each other, one of the main peaks is located to the center frequency f0 of the 1st, that is, the weighted electrode C or its vicinity (that is, within the main lobe) and the trap at both sides of the main peak is located to the 1st side lobe of the 1st electrode C or its vicinity. Thus, the radiation conductance of the 2nd electrode is decreased and the 1st side lobe is suppressed effectively. |
