Design of novel multi-band printed dipole antennas fed by a modified microstrip ring hybrid

In this paper, novel printed dipole antennas fed from end to end are presented for multiple wireless services. Unlike conventional dipole antenna fed from the center, two dipole arms integrated with a modified three-port microstrip ring hybrid, whose sum port is opened, can achieve the model of end-to-end-fed dipole antenna. Because the phase difference and magnitude ratio of signals from two output ports of ring hybrid vary from frequency to frequency, balanced and unbalanced signals can excite dipole antenna with different resonance modes. Dual-band and multi-band novel printed dipole antennas which have simple geometries and can be directly fabricated on PCB board with single microstrip feed are constructed and tested. Proposed antennas are suitable for many wireless communication application, such as WLAN 2.4/5.2GHz, WiMAX 2.6/3.5GHz, ISM band, DCS1800, PCS1900, and UMTS cellular system, etc.