Series-Fed Microstrip Antenna Arrays and Their Application to Omni-Directional Antennas

The analysis of a series feed approach for N-element slot-coupled microstrip antenna arrays is presented. A cylindrical arrangement of six four-element arrays using this feeding mechanism is shown to achieve optimum omni-directional beam characteristics and exhibit pattern stability over frequency in the C-band. The cylindrical arrangement is measured to have a gain of 6 dB over 750 MHz of bandwidth. A closed-form omni-directional pattern analysis is also developed.