Broadband Stub-Loaded Integrated Filtering Antenna for Base Station Applications

This letter presents a broadband stub-loaded integrated filtering antenna with a simple structure for 2G/3G/4G/IMT base station applications. By adding stubs to the dipole arms, new current paths and radiation nulls are introduced, effectively suppressing the radiations outside the passband. Two L-shaped stubs with different lengths introduce controllable radiation nulls at out-of-band to achieve frequency-selective characteristics. Moreover, parasitic patch stubs surrounding the radiator serve to enhance the suppression level at high frequencies. The measured results indicate that impedance bandwidth is 65% and out-of-band suppression performance is more than 16 dB. Stable realized gain of around 8.4 dBi and high isolation of more than 25 dB are obtained within the passband. Moreover, the integrated controllable filtering performance has been validated with filtering antenna array for modern base station applications.