A door approach transmission apparatus comprises an outside door handle 20
having a conductor with a slit 23 disposed in the door handle surface. A
slot antenna 21, 23, 24, 25 is disposed at the slit 23, and includes
feeding points 24, 25 installed on the conductor. The apparatus also
includes a transmitter 26 for applying voltage for radio wave oscillation
to the feeding points 24, 25. The above-described door approach
transmission and reception apparatus can be used in a door lock control
apparatus where a search radio wave is emitted from a vehicle, a portable
wireless device 10 receives the search radio wave, and returns an ID
signal. An electrically driven door lock apparatus 40 is driven to unlock
the door when the returned ID signal coincides with a registered ID
signal. The search radio wave is irradiated from the slot antenna. Either
of a transmitter 26 and a receiver 33 is selectively connected to the
feeding points 24, 25. By virtue of the above-described features, the
emission and reception of radio waves is realized, and in the case of a
door handle made of a metal, the number of parts for emission and
reception of the radio waves are reduced.