@article{srivastava_adams_2022, title={Transient analysis of dynamically switched frequency shift keyed transmitters}, volume={4}, ISSN={["1751-8733"]}, DOI={10.1049/mia2.12237}, abstractNote={A dynamically switched matching network for transmitting a wideband frequency shift keyed (FSK) signal from an electrically small monopole antenna is studied. The effects of switch synchronization, frequency deviation, the antenna's impedance, and Q-factor at the two carrier frequencies are studied. It is found that the average energy per bit of the transmitted FSK waveform is maximum when the loss of reactive energy between states transition is minimised by switching it at the instant of peak voltage across the antenna's terminals. However, a switching network topology that stores more energy is shown to be less sensitive to the synchronization condition. In addition, we show that this dynamically switched system transmits more bit energy when the carriers are closely spaced due to a smaller change in stored energy levels between states. Results are presented using a detailed analytical study and full wave simulation. Near field measurements from a monopole antenna circuit model show that under proper conditions, an FSK signal can be transmitted at a rate 7 times greater than the bandwidth of the transmit antenna with minimal signal quality degradation.}, journal={IET MICROWAVES ANTENNAS & PROPAGATION}, author={Srivastava, Shruti and Adams, Jacob J.}, year={2022}, month={Apr} }
 @article{srivastava_adams_2020, title={Transmission of a broadband FSK signal from a dynamically tuned narrowband antenna}, volume={14}, ISSN={["1751-8733"]}, DOI={10.1049/iet-map.2020.0387}, abstractNote={: A frequency reconfigurable patch antenna is dynamically tuned to transmit frequency-shift keying (FSK) signals over a range of frequencies much broader than the static impedance bandwidth of the antenna. Experiments are conducted for two binary FSK schemes having different carrier spacing. In both cases, dynamic tuning of the antenna is shown to increase the amplitude of the radiated signal by providing a better match than the static antenna. However, the average energy of the radiated bit at each carrier frequency decreases as the symbol rate increases beyond the 3 dB bandwidth of the antenna. Therefore, the bandwidth of the antenna is found to be a limiting factor for the maximum achievable data rate in this scheme. As an alternative to shorter bit durations, the authors show that a higher level FSK scheme using dynamic tuning is able to increase throughput beyond what is possible with a static antenna.}, number={13}, journal={IET MICROWAVES ANTENNAS & PROPAGATION}, author={Srivastava, Shruti and Adams, Jacob J.}, year={2020}, month={Oct}, pages={1651–1654} }