The invention relates to a transmitting / receiving arrangement (11) for a temperature-resistant
radar-based level measuring device (1) which is designed for the efficient transmission and reception of
radar signals (S HF1,2 , R HF1,2 ) in different frequency bands. For this purpose, the transmitting / receiving arrangement (11) is based on a
waveguide (111), by means of which the temperature-sensitive high-frequency units of the level measuring device (1) are spaced from the possibly hot filling material (2). In this case, the
radar signals (S HF1,2 , R HF1,2 ) are transmitted or received via the end region of the
waveguide (111). According to the invention, the
waveguide (111) has an internal cross-section (D) through which only the radar or reception signals (S HF1 , R HF1 ) of the lowest
frequency band propagate exclusively in the fundamental mode, while the radar or reception signals (S HF2 , R HF2) of the higher
frequency band must propagate predominantly in a higher-order mode. In order to ensure that all frequency bands are nevertheless transmitted at the end region with a common
phase center and thus efficiently, a matching element (112) is arranged there according to the invention, which matches the
radar signals (S HF2 ) of the
high frequency band into lower
modes in the direction of
radiation. This design allows the transmit / receive arrangement (11) to be compact and efficient at the same time.