PURPOSE: To obtain a small sized low posture antenna capable of diversity communication by incorporating an inverse-F shaped antenna and a meandering antenna or the like, feeding power individually to transmission and reception parts, using one as a transmission/reception common antenna and using the other as a reception exclusive antenna while replacing antenna with a filter of branching filter structure.

CONSTITUTION: A reception section (not shown in figure) is connected to a feeding coaxial line 6 and a transmission section is connected to balanced feeders 7, 8 via a balancer 9, then the sneak of a transmission wave radiated from a transmission section via an antenna to a reception section is reduced remarkably. Then the transmission wave is replaced by a simple filter of branching filter constitution and the inverse- F shaped antenna covers only a reception frequency band, then the broadwise direction perpendicular to the symmetrical axis is reduced to attain the small sized antenna. Then the transmission/reception section including a branching filter is connected to the feeding coaxial line 6 and another reception section is connected to balanced feeders 7, 8 via a balancer 9, then the directivity diversity reception is attained by the difference in the directivity between the inverse-F shaped antenna 3 and the zigzag strip line antenna 4 and the diversity communication is realized by a small sized antenna system.