@article{huang_schab_dusenbury_sluss_adams_2021, title={DC-Assisted Stabilization of Internal Oscillations for Improved Symbol Transitions in a Direct Antenna Modulation Transmitter}, volume={8}, ISSN={["1557-9670"]}, DOI={10.1109/TMTT.2021.3103209}, abstractNote={Internal oscillations in switched antenna transmitters cause undesirable fluctuations of the stored energy in the system, reducing the effectiveness of time-varying broadbanding methods, such as energy-synchronous direct antenna modulation. To mitigate these parasitic oscillations, a modified direct antenna modulation system with an auxiliary DC source is introduced to stabilize energy storage on the antenna. A detailed circuit model for a direct antenna modulation system is used to identify the origin of the oscillations and to justify the selection of the DC source. Measured phase shift keyed waveforms transmitted using the modified system show significant increases in signal fidelity, including a 10–20-dB reduction in error vector magnitude compared to a time-invariant system. Comparison to an equivalent, scalable time-invariant antenna suggests that the switched transmitter behaves as though it has 2–3 times lower radiation Q-factor and 20% higher radiation efficiency.}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Huang, Danyang and Schab, Kurt and Dusenbury, Joseph K. and Sluss, Brandon and Adams, Jacob J.}, year={2021}, month={Aug} }
 @article{dusenbury_huang_adams_2020, title={A Circuit Model for Energy Synchronous Direct Antenna Modulation Using an Electrically Small Loop}, ISSN={["1522-3965"]}, DOI={10.1109/IEEECONF35879.2020.9329560}, abstractNote={A simple circuit model for a broadband electrically small loop transmitter using energy synchronous direct antenna modulation (DAM) is presented. The concept of energy-synchronous DAM using a loop antenna is briefly described and compared to a conventional narrowband transmitter, via time domain simulations of the current on the loop. A brief analysis of the affect of ohmic loss on the stored current is presented. Initial results suggest that the dissipation in the loop is negligible over short symbol durations, but motivates a discussion about the need for a more comprehensive parametric study for this class of DAM transmitters.}, journal={2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING}, author={Dusenbury, Joseph and Huang, Danyang and Adams, Jacob J.}, year={2020}, pages={459–460} }
 @article{schab_huang_adams_2020, title={An Energy-Synchronous Direct Antenna Modulation Method for Phase Shift Keying}, volume={1}, ISSN={["2637-6431"]}, DOI={10.1109/OJAP.2020.2972842}, abstractNote={A novel scheme for transmitting broadband phase shift keyed signals from electrically small antennas using energy-synchronous direct antenna modulation is described. We outline fundamental operating principles of the method and experimentally compare its performance to that of a conventional band-limited transmit antenna with the same electrical size and radiation efficiency. Transmitted waveforms are analyzed in the time domain both at RF and baseband. Results show significant increases in signal quality, suggesting a larger effective transmit bandwidth and greater potential throughput when the proposed direct antenna modulation scheme is used.}, journal={IEEE OPEN JOURNAL OF ANTENNAS AND PROPAGATION}, author={Schab, Kurt and Huang, Danyang and Adams, Jacob J.}, year={2020}, pages={41–46} }
 @article{huang_adams_schab_2020, title={Investigation of Ringing Effects on Phase Shift Keyed Direct Antenna Modulation Transmitters}, ISSN={["1522-3965"]}, DOI={10.1109/IEEECONF35879.2020.9330246}, abstractNote={In this paper, a method of direct antenna modulation (DAM) transmitting phase shift keyed (PSK) high data rate signals using a narrowband antenna is described. We analyze the result of an over the air DAM PSK measurement and degradation are observed in QPSK DAM compared to the ideal case. We demonstrate that it is the parasitics of the circuit that reduce the ability of the system to store voltage and achieve fast transitions, particularly between certain combinations of symbols. This degradation is studied and it can be predicted by circuit model simulation.}, journal={2020 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION AND NORTH AMERICAN RADIO SCIENCE MEETING}, author={Huang, Danyang and Adams, Jacob J. and Schab, Kurt}, year={2020}, pages={1817–1818} }
 @article{yu_lu_huang_2020, title={MODELING AND ESTIMATION OF CONTAGION-BASED SOCIAL NETWORK DEPENDENCE WITH TIME-TO-EVENT DATA}, volume={30}, ISSN={["1996-8507"]}, DOI={10.5705/ss.202018.0222}, abstractNote={: Social network data consists of social ties, node characteristics and behaviors over time. It is known that people who are close to each other in a social network are more likely to behave in a similar way. One of the reasons they act similarly is due to the peer influence and social contagion that acts along the network ties. A primary interest of social network data analysis is to identify the contagion-based social correlation. In this work, we model and estimate the contagion-based social network dependence based on time-to-event data. A generalized linear transformation model is proposed for the conditional survival probability at each observed event time, which uses a time-varying covariate to incorporate the network structure and quantify the contagion-based social correlation. We develop the nonparametric maximum likelihood estimation for the proposed model. The consistency and asymptotic normality of the resulting estimators for the regression parameters are established. Simulations are conducted to evaluate the empirical performance of the proposed estimators. We further}, number={4}, journal={STATISTICA SINICA}, author={Yu, Lin and Lu, Wenbin and Huang, Danyang}, year={2020}, month={Oct}, pages={2051–2074} }
 @article{su_lu_song_huang_2020, title={Testing and Estimation of Social Network Dependence With Time to Event Data}, volume={115}, ISSN={["1537-274X"]}, DOI={10.1080/01621459.2019.1617153}, abstractNote={Abstract Nowadays, events are spread rapidly along social networks. We are interested in whether people’s responses to an event are affected by their friends’ characteristics. For example, how soon will a person start playing a game given that his/her friends like it? Studying social network dependence is an emerging research area. In this work, we propose a novel latent spatial autocorrelation Cox model to study social network dependence with time-to-event data. The proposed model introduces a latent indicator to characterize whether a person’s survival time might be affected by his or her friends’ features. We first propose a score-type test for detecting the existence of social network dependence. If it exists, we further develop an EM-type algorithm to estimate the model parameters. The performance of the proposed test and estimators are illustrated by simulation studies and an application to a time-to-event dataset about playing a popular mobile game from one of the largest online social network platforms. Supplementary materials for this article, including a standardized description of the materials available for reproducing the work, are available as an online supplement.}, number={530}, journal={JOURNAL OF THE AMERICAN STATISTICAL ASSOCIATION}, author={Su, Lin and Lu, Wenbin and Song, Rui and Huang, Danyang}, year={2020}, month={Apr}, pages={570–582} }
 @article{schab_huang_adams_2019, title={Pulse Characteristics of a Direct Antenna Modulation Transmitter}, volume={7}, ISSN={["2169-3536"]}, DOI={10.1109/ACCESS.2019.2902365}, abstractNote={Direct antenna modulation (DAM) methods using time-varying matching networks offer the possibility to reduce the detrimental effects on broadband signal transmission from a narrowband antenna. We propose time- and frequency-domain models for the effects of a DAM scheme for the transmission of ON–OFF-keyed RF signals and test the validity of the proposed models through over-the-air measurements at 27.12 MHz. Random bit sequences are transmitted separately using both a switched-mode DAM transmitter and a conventional transmitter and received in the far field. Comparison of measured data with our frequency-domain models shows that the DAM transmission method partially removes the effects of narrowband filtering due to the transmit antenna. Models and measurements also demonstrate that the removal of this filter improves the signal quality as observed in eye diagrams of the demodulated received signals. Finally, a simple time-domain model of the DAM transmitter is shown to predict the radiated transient signal under varying synchronization conditions.}, journal={IEEE ACCESS}, author={Schab, Kurt and Huang, Danyang and Adams, Jacob J.}, year={2019}, pages={30213–30219} }
 @article{hedin_huang_wu_zhang_2019, title={Substrate Integrated E-Plane Waveguide (SIEW) to Design E-Plane and Dual Polarized Devices}, volume={67}, ISSN={["1558-2221"]}, DOI={10.1109/TAP.2018.2885459}, abstractNote={Substrate-integrated waveguide (SIW) uses rows of plated through holes to emulate the intact vertical walls of a waveguide circuit. It succeeds in the design of H-plane circuits but not the E-plane circuits because an E-plane circuit requires longitudinal current on the vertical walls that is not supported by SIW. In this paper, a novel substrate-integrated E-plane waveguide (SIEW) is presented. In SIEW, additional copper strips are inserted at the middle layer of the structure while the copper plated through holes remain unchanged. Consequently, the vertical current flows on the through holes and the longitudinal current flows along the middle strips to meet the wave propagation requirement in the E-plane waveguide circuit. The insertion loss, cutoff frequency, and propagation constant of the SIEW are investigated. As examples, an empty SIEW, a bandpass septum SIEW filter, and a dual-polarized SIEW horn antenna are designed using the SIEW technique. All of them are constructed and their performance is measured to validate the design.}, number={3}, journal={IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION}, author={Hedin, Michael and Huang, Danyang and Wu, Xuan Hui and Zhang, Qun}, year={2019}, month={Mar}, pages={1844–1853} }