Frequency agile small smart antenna

In this paper, a frequency agile small smart antenna composed of a compact Electronically Steerable Passive Array Radiator (ESPAR) antenna is presented. The frequency agile range from 2.3GHz to 2.6GHz is examined in terms of return loss, antenna gain and radiation pattern. Proposed frequency agile smart antenna is electrically small in size. Tightly coupled top-disk loaded monopole and folded monopoles are used to reduce height of ESPAR antenna. The height of proposed ESPAR antenna is lower than 1/10 wavelength. The radius of proposed ESPAR antenna is smaller than 1/4 wavelength. Proposed antenna reports a maximum gain of 4.0dBi and a front-backratio about 12dB. Fluctuation of antenna gain over different frequencies is studied and presented in this paper. Beamforming can be achieved by tuning reactive loads in series with those parasitic folded monopoles surrounding centre driven top-disk loaded monopoles.