Broadband Printed Dipole Antennas with Shaped Ground Plane

A printed dipole antenna, in spite of its numerous advantages in terms of size, weight, aerodynamic drag etc. suffers from the inherent disadvantage of incompatibility with wide band operation. Both microstrip dipoles and printed dipoles are resonant antennas but printed dipoles are often used to replace microstrip dipoles since they offer somewhat better band width. However, the maximum band width reported to be obtained is not sufficient for many present day high-speed data applications like streaming video, real time navigation and control links, as also applications like medical imaging, broad band EMI measurements etc. A novel yet simple design of printed dipole antenna without flared arms and with shaped ground plane is presented here using which - 10 dB return loss band width as high as 41% in L band and below is achieved, a feat hitherto unachieved. By flaring its arms, the same antenna provides -10dB band width as high as 51% in the same band of frequency. Antennas are designed to operate in L band and below so that these can be used in GSM and CDMA wireless applications. Measured results of both antennas show good agreement with the simulated results.