The working principles of coplanar-waveguide (CPW) -fed, ultra-wideband (UWB) printed antennas are investigated. The behavior of the current distributions at different frequencies are examined. The modifications in the current distributions when the phase of the currents changes lead us to some conclusions on the behavior of UWB antennas.@en

The linear array performance of an ultrawideband (UWB), coplanar waveguide (CPW) fed, printed, loop antenna is investigated by means of simulations and measurements. The UWB properties of the array are demonstrated by synthesizing the array reflection coefficient, starting from the simulated and measured scattering matrices. The array is proven to have a VSWR ¿ 2 fractional impedance bandwidth of 64%, stretching between 7 GHz and 13.6 GHz. The performance of a complete, non-scanning, broadside array are examined by feeding the array via a Wilkinson power divider. The study is completed by radiation pattern measurements that show stable co-polar and low cross-polar characteristics over the operational bandwidth.@en

It is possible to find various antennas in the literature covering the UWB frequency range stretching between 3.1 GHz and 10.6 GHz, as the UWB technology has gained much popularity in the recent years. These antennas have some deficiencies. Some of these antennas are electrically large, so it is difficult to use them in array environments and some of them have acceptable time domain behaviors up to a limited frequency, only. For example, the circular slot antenna investigated in [1] has a width of more than 29 mm, corresponding to 0.64 ¿ at the central frequency of the UWB band (6.6 GHz), which makes it difficult to use this antenna in array environments. Similarly, a planar bell-shaped antenna investigated in [2] has the same electrically big size problem; the maximum size of the antenna is 86 mm which corresponds to 0.89 ¿ at 6.6 GHz.@en