Coupler having arbitrary impedance transformation ratio and arbitrary coubling ratio

A microstrip circuit operable at microwave frequencies for power combining two amplifiers in which the optimum input impedance of at least one of said amplifiers differs from the input impedance of said circuit, said circuit comprising:

• a power dividing coupler consisting essentially of four series-connected microstrip branches and having two input ports and two output ports;
• wherein
• a first branch has a normalized admittance equal to 1/.sqroot.k;
• second branch has a normalized admittance equal to 1/(Z.sqroot.k);
• and
• a third and fourth branch each have normalized admittances equal to .sqroot.1/(Zk)+(1/Z);
• where Z is the desired impedance transformation ratio of the coupler and k is the desired power coupling ratio, k not being equal to one;
• two amplifiers, the input of each of which is connected to a different one of said output ports of said power dividing coupler;
• and
• a power combining coupler having two input ports and two output ports;
• wherein
• the outputs of each of said amplifiers are connected to a different one of said input ports of said power combining coupler;
• wherein a different amount of power flows through each of said amplifiers;
• and
• said power dividing coupler has a power division ratio other than one and simultaneously matches the input impedance of the circuit to the optimum input impedances of said amplifiers.

A microstrip circuit operable at microwave frequencies for power combining two amplifiers in which the optimum output impedance of at least one of said amplifiers differs from the output impedance of said circuit, said circuit comprising:

• a power dividing coupler having two input ports and two output ports;
• two amplifiers, the input of each of which is connected to a different one of said output ports of said power dividing coupler;
• and
• a power combining coupler consisting essentially of four series-connected microstrip branches and having two input ports and two output ports;
• wherein
• a first branch has a normalized admittance equal to 1/.sqroot.k;
• second branch has a normalized admittance equal to 1/(Z.sqroot.k);
• and
• a third and fourth branch each have normalized admittances equal to .sqroot.1/(Zk)+(1/Z);
• where Z is the desired impedance transformation ratio of the coupler and k is the desired power coupling ratio, k not being equal to one;
• wherein the outputs of each of said amplifiers are connected to a different one of said input ports of said power combining coupler;
• wherein a different amount of power flows through each of said amplifiers;
• and
• said power combining coupler has a power combination ratio other than one and simultaneously matches the output impedance of the circuit to the optimum output impedances of said amplifiers.