Study of Ultra-wideband Antenna with Multi-notch Band Loaded with a Multimode Electric Ring Resonator and a Complementary Resonance Structure

A multi-notch ultra-wideband (UWB) planar antenna designed as a circular metallic patch fed by a coplanar waveguide (CPW) is of high interest. The antenna provides a stable radiation pattern and impedance bandwidth of the wideband response in the frequency range 2.5 - 12 GHz. To achieve the band-notched characteristics of the planar UWB antenna, the multi-mode electric ring resonator (ERR) is used. The ERR is placed beneath the CPW structure of the antenna. Each of the notched frequency band is tuned by proper changing the dimensions of the ERR structure. The UWB antenna exhibits multi-notch characteristics in the 2.5–12 GHz frequency band at 3.5, 5.8, and 7.5 GHz. Reconfigurability of the notched band is provided by using variable capacitors instead of ERR quasi-lumped capacitances. As an alternative approach a circular metallic patch antenna fed by a microstrip transmission line may be used. In this case, the notch is provided by a complementary inductance-capacitance (C-ELC) resonator in the ground plane of the microstrip line. The notch frequency depends on the dimensions of the C-ELC resonator.