Printed quasi-Yagi antenna with folded dipole driver

A design for a new quasi-Yagi antenna suitable for fabrication on low-cost, low dielectric constant materials such as LCP was developed by replacing the half-wavelength dipole driver element with a folded dipole. The input impedance of the folded dipole quasi-Yagi antenna and its resonance frequency may be tuned by properly adjusting the parameters of the folded dipole giving more freedom for optimization of a single element compared to a standard quasi-Yagi antenna. The new antenna achieves a predicted impedance bandwidth (|S₁₁|<-10dB) of 24% and the radiation characteristics are similar to the conventional quasi-Yagi antenna fabricated on high dielectric permittivity substrates. The front-to-back ratio of the new antenna is greater than 13dB across the bandwidth and the realized gain is in the range of 3-7dBi. On low dielectric permittivity substrates, the folded dipole is more compact compared to the standard quasi-Yagi antenna and so is more suitable for applications requiring phased arrays where the length of a half-wavelength dipole becomes close to the commonly used 0.5 lambda₀ spacing between the array elements.