ABSTRACT
This study presents the design of a uniplanar crossed-dipole antenna with broadband characteristics. The antenna comprises a pair of identical crossed-dipole arms printed on the same plane of a dielectric substrate. The crossed-dipole arms are corner-cut fat dipoles that are perpendicular to each other and connected with a bent stripline to generate circularly polarised (CP) radiations. A wide dipole arm was used to improve impedance matching and widen the axial ratio (AR) bandwidth. Additionally, the corner of each dipole arm was cut into a triangular shape to broaden the impedance and AR bandwidths further. The antenna in free space is excited via a wideband microstrip-to-parallel stripline tapered balun to reduce the effect of leakage current on the coaxial cable. Experiments and full-wave electromagnetic simulations were employed to design, verify, and validate the antenna design. The antenna, having an overall size of 45 × 45 × 0.508 mm3 (0.4 × 0.4 × 0.0045 λL3 where λL is the lowest frequency in the 3-dB AR bandwidth), demonstrates the following measured performances: an |S11|< - 10 dB impedance bandwidth of 2.53-9.14 GHz (113.3%), a 3 dB AR bandwidth of 2.65-7.75 GHz (98.1%), and peak gain of 3.7 dBic at 6.6 GHz.
ABSTRACT
This paper presents an ultra-low-profile copper indium gallium selenide (CIGS) based solar cell integrated antenna with a high form factor. A tiny slot was etched from the solar cell to develop an ultra-low-profile solar-cell-integrated antenna. This tiny slot increases the form factor due to the small clearance area from the solar cell. A ground-radiation antenna design method was applied in which lumped elements were employed inside the tiny slot for antenna operation. Another substrate was used under the solar cell for designing the feeding structure with lumped elements connected to the tiny slot using via holes. A prototype was fabricated and measured to verify the operation of a built-in solar-cell antenna and validate the simulated results. The measured results demonstrate that the solar-cell-integrated antenna covers the entire frequency range of the Industrial Scientific Medical band, from 2.4 to 2.5 GHz, with a maximum gain of 2.79 dBi and radiation efficiency higher than 80% within the impedance bandwidth range. Moreover, the proposed design has an ultra-low-profile structure of only 0.0046 λo, where λo represents the free space wavelength at 2.45 GHz, and a high form factor of 99.1% with no optical blockage. The antenna and solar cell were designed to avoid affecting the performance of each other using the radio-frequency decoupler.
