A Compact Three-Way Power Divider With Third-Harmonic Suppression

This paper presents a compact three-way power divider with third-harmonic suppression. The design of the proposed power divider is accomplished by adding three open-ended stubswhich located at the end of each quarter-wave branch transformer, and two parallel connections of a resistor and an inductor. The schematic and Configuration of the proposed power divider are given. A set of formulas are also given to simplify the design procedure of the divider. The lengths of the open-ended stubs are fixed to lambda/4n, where n is the order of the harmonic component to be suppressed, and. is the wavelength of the operating frequency. An equation is obtained after a series of derivation process in detail. This equation describes the relationship of characteristic impedance of transformer segment and open ended stub With the help of the optimization capability of the software Ansoft HFSS after performing the circuit design using the software AWR, parameters of the divider are found that the optimized values of the design parameters are less than 15% different from those obtained by the described design method, which indicates the high accuracy of the proposed design method. To verify the validity of the solution, a three-way power divider at 1.5 GHz is fabricated and measured. Experimental results show that this power divider can suppress the third harmonic component to less than -42 dB, while maintaining conventional performance at the fundamental frequency. Good experimental performances, including an equal power split, low return loss, and good isolation between the output ports are obtained. In addition, the size of the proposed power divider is about half compared with that of the conventional one. The proposed power divider can reduce the external interference and size of array antenna due to the third harmonic suppression and size reduction. So it can be widely applied to phased array antenna systems.