Patent ID: 7577416

Claim:
A single balanced mixer for converting an input RF signal to an IF (intermediate frequency) signal by mixing the input RF signal with a local signal, comprising: a first hybrid coupler for, upon receiving the local signal, producing two local signals of same amplitude and opposite phase; a pair of mixing elements each receiving a corresponding one of the two local signals from the first hybrid coupler; a pair of λ/4 strip lines for transmitting the input RF signal to the mixing elements, one end of each of the λ/4 strip lines being connected to one another at a point where the input RF signal is supplied and other end of each of the λ/4 strip lines being connected to the corresponding mixing element; a pair of IF filters for filtering the IF signals of opposite phase produced at the mixing elements; and a second hybrid coupler for combining the IF signals from the IF filters to produce the IF signal of same phase; wherein a length of each of the λ/4 strip lines is one fourth of a wave length λ of the IF signal.