Please note that the content of this book primarily consists of articles
available from Wikipedia or other free sources online. Following and
exploiting the concept of SDR, SDA is an idea of antenna system that can
be adjusted in such way, to keep similar characteristics for any
frequency. Once installed, SDA could be used to support any radio-based
telecommunication system in any band, with the same level of
performance. I.e. GSM 900 MHz, then UMTS after migration to 2100 MHZ
followed by LTE in 2600 MHz band. The first mathematical research began
in late 1950s focusing on steering the side lobes of radar receivers to
be less susceptible to jamming, but only recently a rapid development of
SDR technology has caused manufacturers to pay more attention to this
subject.
