Stable End-fire Radiation Patterns Research Articles

Planar Wideband Loop-Dipole Composite Antenna

A novel planar wideband balanced composite antenna is presented. The proposed antenna consists of a symmetrical dipole and an antipodal loop radiator. The return loss, radiation pattern, and gain of the antenna are numerically and experimentally studied. An impedance bandwidth of 129% (20 log |S11| <; -10dB) from 3.26 to 15 GHz has been obtained. Stable end-fire radiation patterns with good polarization purity and flat gain performances are obtained across the operating frequency range. In addition, the time domain responses of the proposed antenna are investigated. The proposed antenna can be used in compact wireless devices for point-to-point applications.

Wideband Self-Complementary Quasi-Yagi Antenna for Millimeter-Wave Systems

Novel wideband quasi-Yagi antennas, each featuring a self-complementary structure together with a triangular notch on the ground plane, are proposed. The optimized proposed antenna offers an improved relative bandwidth of 74%, gain of 4-8 dBi, and stable endfire radiation patterns within the passband. Good agreement between simulation and measurement is shown.

A Double Rhombus Antenna Fed by 180$^{\circ}$ Phase Shifter for Ultrawideband Phased Array Applications

A double rhombus antenna fed through a microstrip 180deg phase shifter is presented. The 180deg phase shifter is a novel design of microstrip-to-coplanar waveguide (CPW)-to-microstrip transition. The proposed phase shifter is obtained without changing the layer of the second microstrip line for an easy embedding into the feedline. Via holes are used to transfer the current from the top to the bottom substrate layer and vice versa. The antenna with the phase shifter is operating in a wide bandwidth from 5.7 and 18.6 GHz (106%), and provides stable endfire radiation patterns. This design is tested in a modified two-element array configuration and proved to have a wide usable bandwidth.