Dual-band microstrip antennas using λ/4 parasitic elements stacked on radiation apertures

This paper presents a dual-band microstrip antenna using the stacked λ/4 parasitic elements for GPS applications. The proposed antenna was designed at GPS L
₁
(1.575 GHz) and L
₂
(1.227 GHz) bands. For designing dual-band microstrip antenna, a λ/4 parasitic element was stacked at the radiation apertures on the half-wavelength microstrip patch antenna. Therefore, the proposed antenna had linear polarization and occurs resonance through coupling between the patch and parasitic element. However, the radiation pattern occurring with patch and parasitic element was different commercial patch antenna's pattern. To compensate gain and radiation pattern, two λ/4 parasitic elements were stacked on the patch. The fabricated antenna had dimensions of 0.45λ
_L
× 0.43λ
_L
× 0.04λ
_L
, where λ
_L
is free-space wavelength at 1.227 GHz. Measured -10 dB bandwidths were 25 MHz (1.59%) at L
₁
band, and 39 MHz (3.18%) at L
₂
band, respectively. Each of the designed bands, the broadside radiation patterns were observed.