Antenna apparatus having individual transmitting and receiving antenna elements for different frequencies

#1. Field of the Invention

#The present invention relates to a mobile satellite communication system, and more particularly, to an antenna apparatus provided at a mobile station for communication with a satellite.

#2. Description of the Related Art

#The present invention will be more clearly understood from the description as set forth below, as compared with the prior art, with reference to the accompanied drawings, wherein:

#FIG. 1 is a circuit diagram illustrating a prior art antenna apparatus;

#FIG. 2 is a diagram showing a directivity characteristic of the apparatus of FIG. 1;

#Before the description of the preferred embodiment, a prior art antenna apparatus will be explained with reference to FIGS. 1 and 2.

#In FIG. 1, which illustrates a prior art antenna apparatus, the antenna apparatus includes a single antenna element 1 for carrying out communication with a satellite SAT, a high frequency unit 2, a radio control unit 3, and a meter 4 for monitoring a receiving state of the antenna element 1. In more detail, the high frequency unit 2 is comprised of a synthesizer 21, mixers 22T and 22R, a high power amplifier 23T, a low noise amplifier 23R, and band pass filters 24T and 24R. The mixer 22T, the high power amplifier 23T and the band pass filter 24T generate a signal having a transmitting frequency TX, and transmit it via the antenna element 1 to the satellite SAT. On the other hand, the band pass filter 24R, the low noise amplifier 23R and the mixer 22R receive a signal having a receiving frequency RX via the antenna element 1 from the satellite SAT.

#Also, the radio control unit 3 is comprised of a baseband processor 31 and the like. Further, the meter 4 is connected to the low noise amplifier 23R.