  The performance of broadband millimeter-wave (mmWave) RF architectures, is
generally determined by mathematical concepts such as the Shannon capacity.
These systems have also to obey physical laws such as the conservation of
energy and the propagation laws. Taking the physical and hardware limitations
into account is crucial for characterizing the actual performance of mmWave
systems under certain architecture such as analog beamforming. In this context,
we consider a broadband frequency dependent array model that explicitly
includes incremental time shifts instead of phase shifts between the individual
antennas and incorporates a physically defined radiated power. As a consequence
of this model, we present a novel joint approach for designing the optimal
waveform and beamforming vector for analog beamforming. Our results show that,
for sufficiently large array size, the achievable rate is mainly limited by the
fundamental trade-off between the analog beamforming gain and signal bandwidth.
