Rhombic Grid Array Antenna

A rhombic grid array antenna (RGAA) is proposed and its frequency-scanning performance is discussed. The RGAA has numerous bent radiation elements, forming rhombic cells and loops. As the frequency is increased, the radiation beam from the RGAA becomes a forward-fire beam. It is found that, as the bend angle of the radiation elements is decreased, the useful antenna characteristics shift to a lower frequency region. It is also found that the RGAA provides a more stable gain within a frequency band bounded by the 3- and 4-guided-wavelength resonances of the loops, compared with a conventional grid array antenna having non-bent radiation elements. Further investigation reveals that the VSWR is small within a frequency band bounded by the 3- and 4-guided wavelength resonances, as desired, and the bend radiation elements of the RGAA contribute to increasing the radiation efficiency.