Electrically Small Antennas in High-Density, Broadband Arrays

A design concept for transmitting and receiving antenna arrays that allow for less mutual coupling and close proximity of components is described. The suggested approach employs the Bode matching theory to connect electrically small antennas with high reactance and low radiation resistance to front ends with high/low impedance. This method permits the concurrent achievement of miniaturization, proximity, and broadband properties. Finally, the suggested method is implemented by an array of four-element electrically small antennas in a 25mm-by-25mm ground plane over a frequency range of 1 GHz to 7 GHz. The proposed array can be used over a broad frequency band while the mutual coupling is below -20 dB. This approach applies to MIMO/SIMO and sensor system applications.