**7. Conclusions**

180 Ultra Wideband – Current Status and Future Trends

*6.3.2. Transmission amplitude dispersion* 

*6.3.3. Transmission phase delay and group delay* 

the magnitude plot (fig.18a).

To evaluate the amplitude spectral dispersion of the prototype 4, the measured time-domain transmission scattering coefficients of the three co-polar configurations (00, 450, and 900 configurations displayed in fig.16) were Fourier-transformed in to frequency domain. The measured magnitudes are plotted in fig.18a, the measured results show a smooth and flat

The measured phase responses of the transmission parameter for the three co-polar configurations are plotted in Fig.18b. In narrowband technology, the phase delay defined as τP =– ө/ω, is a metric for judging the quality of the transmission is the phase delay between the input and output signals of the system at a given frequency. In wideband technology, however, group delay is a more precise and useful measure of phase linearity of the phase response (Chen, 2007). The transmission group delays for the three above-mentioned configurations are plotted in Fig.18c. The plots show an excellent and negligible group delays in the order of sub-nanosecond, this is no surprise because the phase responses of the prototype are almost linear (fig.18b), thus the group delay, which is defined as the slope of the phase with respect to frequency τG =– dө/dω, resulted accordingly. Note: although the group delay (fig.18c) is mathematically defined as a constituent directly related to the phase, but it was impossible to visually observe directly from the phase plot (fig.18b), but well from

**Figure 18.** Measured in-band transmission coefficients a) magnitude, b) phase, c) group delay.

amplitude distribution in the designated band, and all are lower than -42dBm.

The intent message of this report focusses on the concept, the design methodology and the pragmatic simplification of MVO process in to a SVO one.

Distinct concepts and definitions are defused and corrected. An SWB-antenna topology with simplest structure is proposed. The single layer topology paved the way for the creating of the obtained SWB antenna architecture. The antenna architecture supported, in turn, the FSD. The introduced design methodology and conceptual concept are consolidated by the developed prototypes.

The antenna architecture provides powerful isolated-parameters to control the antenna characteristics, such as resonance-shifting, resonance matching, bandwidth broadening, diffraction reduction, and SWB pattern maintaining.

The FSD approach is introduced to obtain the required performance, whilst keeping the overall dimension of the radiator fixed, the separated sections provide engineering insights, and can be designed or optimized almost independently.

Parameter order and SVO methodology are elaborated in details, the priority and role of separable parameters are identified, and so, instead of multivariable-optimization, the optimization process can be accelerated by carry out sequence of SVOs. The proposed design, optimization procedure can possibly be used as a gauging-process for designing or optimizing similar SWB structures.

Although the prototype 4 comprised a simplest structure and shape, however superior SWB impedance bandwidth is obtained and stable SWB-patterns are uniquely preserved.

This structure, although, can be modified to obtain huge frequency bandwidth, but cannot be one-size-fit-all for gain-size requirement. However, the architecture is flexible enough for scaling up/down its dimensions to match customer's gain-size requirement.

SWB prototype is designed, fabricated and evaluated for the super wideband impasse, and could possibly be used as an alternative radiator for the sub-millimeter-wave regime.

Performances of the prototype are tested and evaluated. Good agreements between numerical predictions and measurements are obtained.

Due to editorial limits, we exclusively report here only the design methodology and conceptual approach; detailed mathematical formulation and numerical aspects related to this SWB prototype will be published in another occurrence.
