Abstract: A method for securing the operation of a receiver in a two-way radio apparatus by enhancing the isolation between the transmitter and receiver, and a radio apparatus employing said method. The transmitter and receiver in a radio apparatus have separate antennas (320, 330). The transmitter has at least two mutually alternative filters which have different attenuations in the receive band. Transmitting antenna matching is monitored by measuring the strength of the field (re) reflected from the antenna (320) towards the power amplifier (PA). When the strength of the reflected field in proportion to the strength of the propagating field is above a certain threshold, the filter (312) which has a greater stop-band attenuation in the receive band will be used as the transmitting filter. Otherwise, the filter (311) which has a smaller stop-band attenuation and, hence, smaller pass-band attenuation will be used as the transmitting filter.

Abstract: A method and device for achieving space diversity reception in a system that has a first antenna and a second antenna disposed apart from each other over a quarter wavelength of the operating frequency, wherein the first antenna is optimally tuned to a first frequency for receiving signals in an operating mode. In its first function, the second antenna is optimally tuned to a second frequency for transmitting signals in the same mode or for receiving signals in a different mode. In its second function, the second antenna can be tuned to the first frequency so that it also receives signals in the first frequency in the same mode as the first antenna. The signals in the first frequency received by the second antenna are combined with the signals received by the first antenna.

Abstract: In an antenna structure having a transmit antenna disposed over a first section of a ground plane and a receive antenna disposed over a second section of the ground plane, a cut is provided between the first and second sections of the ground plane. The length of the cut is substantially equal to one quarter-wavelength of the operating frequency band of transmit/receive antenna pair so as to provide isolation between the transmit antenna and the receive antenna. If the antenna structure also has a transceiver antenna operated in a further frequency band disposed over the same ground plane and straddling over the first section and the second section, a switch is provided over the cut. The switch is operating in a closed position when the transceiver antenna in the further frequency band is used, and in an open position when the transmit/receiver antenna pair is used.

Abstract: In an antenna structure having a transmit antenna disposed over a first section of a ground plane and a receive antenna disposed over a second section of the ground plane, a cut is provided between the first and second sections of the ground plan The length of the cut is substantially equal to one quarter-wavelength of the operating frequency band of transmit/receive antenna pair so as to provide isolation between the transmit antenna and the receive antenna. If the antenna structure also has a transceiver antenna operated in a further frequency band disposed over the same ground plane and straddling over the first section and the second section, a switch is provided over the cut. The switch is operating in a closed position when the transceiver antenna in the further frequency band is used, and in an open position when the transmit/receiver antenna pair is used.

Abstract: A method and device for achieving space diversity reception in a system that has a first antenna and a second antenna disposed apart from each other over a quarter wavelength of the operating frequency, wherein the first antenna is optimally tuned to a first frequency for receiving signals in an operating mode. In its first function, the second antenna is optimally tuned to a second frequency for transmitting signals in the same mode or for receiving signals in a different mode. In its second function, the second antenna can be tuned to the first frequency so that it also receives signals in the first frequency in the same mode as the first antenna. The signals in the first frequency received by the second antenna are combined with the signals received by the first antenna.

Abstract: A method for securing the operation of a receiver in a two-way radio apparatus by enhancing the isolation between the transmitter and receiver, and a radio apparatus employing said method. The transmitter and receiver in a radio apparatus have separate antennas (320, 330). The transmitter has at least two mutually alternative filters which have different attenuations in the receive band. Transmitting antenna matching is monitored by measuring the strength of the field (re) reflected from the antenna (320) towards the power amplifier (PA). When the strength of the reflected field in proportion to the strength of the propagating field is above a certain threshold, the filter (312) which has a greater stop-band attenuation in the receive band will be used as the transmitting filter. Otherwise, the filter (311) which has a smaller stop-band attenuation and, hence, smaller pass-band attenuation will be used as the transmitting filter.