Capacitor-based phase shifter for 8 elements antenna feeding network

This paper deals with the development of 8 elements capacitor-based phase shifter for 2.4GHz antenna feeding network. The phase shifting is achieved by using loaded-line phase shifter technique implemented by placing capacitor chips at the edge between 50Ω and 70.71Ω transmission lines. The feeding network consists of microstrip transmission lines and matching impedance lines designed using a quarter wavelength transformer method and deployed on an FR4 Epoxy dielectric substrate with relative permittivity of 4.3, thickness of 1.6mm and dimension of 50mm × 300mm. The feeding network is configured at 4 different scenarios with various capacitance values. The first scenario is no capacitor chips added into the microstrip lines; while at the second and third scenarios, 1pF and 10pF capacitor chips are put on each line of output port, respectively; and at the forth scenario, capacitor chips with the consecutively value of 10pF, 3pF, 1pF, 1pF, 1pF, 1pF, 3pF, 10pF are placed for each microstrip line. From the result, it shows that the proposed capacitor-based phase shifter for 8 elements antenna feeding network is suitable for 2.4GHz operating frequency with the measured phase shifting up to 40° for capacitance value of 1pF.