Switching of Reactive Elements in High-Q Antennas

Galejs, Janis

doi:10.1109/tcom.1963.1088740

Cited by 25 publications

(24 citation statements)

References 1 publication

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“…This work focuses on the analysis of an energy-synchronous DAM scheme for transmitting broadband OOK signals using electrically small dipole antennas, originally proposed in [4]. Here, we simply denote this scheme as DAM OOK and provide a brief explanation of the concept.…”

Section: Energy-synchronous On-off-keyingmentioning

confidence: 99%

Pulse Characteristics of a Direct Antenna Modulation Transmitter

2019

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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 frequencydomain 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. INDEX TERMS Antenna measurements, electrically small antennas, narrowband antennas, time varying circuits.

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Section: Energy-synchronous On-off-keyingmentioning

confidence: 99%

Pulse Characteristics of a Direct Antenna Modulation Transmitter

2019

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“…To avoid the aforementioned limitations imposed by a conventional narrowband transmitter, we propose the following technique based on direct antenna modulation (DAM). The core concepts of this method are adapted from an energysynchronous technique for on-off-keying [5], [12], [13]. The key element of that technique (discussed in detail in [13]) is the use of a precisely-synchronized switched matching network to capture and release electric energy on the antenna structure to facilitate rapid transitions between a radiating and non-radiating state, thus avoiding detrimental charging and discharging times similar to those appearing in (1).…”

Section: Energy-synchronous Psk Schemementioning

confidence: 99%

“…Extension to modulation classes involving both amplitude and phase modulation (e.g., QAM) are not directly implementable using this method because the amplitude changes necessitate increases or decreases of stored energy on the antenna. However, implementing DAM versions of QAM-like modulation may be possible in the future using a combination of the binary amplitude control applied in DAM OOK [5], [13] and the phase control method presented here.…”

Section: Extension To Higher Order Modulationmentioning

confidence: 99%

An Energy-Synchronous Direct Antenna Modulation Method for Phase Shift Keying

Schab

Huang

Adams

2020

IEEE Open J. Antennas Propag.

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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. INDEX TERMS Electrically small antennas, direct modulation, antenna measurements, phase shift keying, time-varying circuits.

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“…However, neither of these sophisticated matching techniques, which can be applied to increase the bandwidth of any single-resonance ESA, will be considered in this study. Also, increasing the bandwidth with active, non-linear, or time-varying matching networks [24][25][26] will not be considered here.…”

Section: Fundamental Relations Between Impedance Bandwidth and Qualmentioning

confidence: 99%

Overcoming the Chu lower bound on antenna Q with highly dispersive lossy material

Yaghjian

2018

IET microw. antennas propagation

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Beginning with a brief overview of the history of lower bounds on the quality factor Q of antennas and the fundamental relationships between the impedance, bandwidth, and Q of antennas, it is demonstrated by means of RLC circuit models of electrically small antennas that their isolated‐resonance quality factors obtained from the ‘Q‐energy’ predicts their bandwidths with greater accuracy than the ‘equivalent‐circuit’ energies or the ‘electrodynamic’ energies. A generalisation is obtained for quasi‐static fields of antennas that facilitate the evaluation of the expressions for the Q‐energy. It is verified that the Q‐energy cannot be considered stored energy in the highly dispersive lossy material. Nonetheless, using tuning elements containing highly dispersive lossy material, the bandwidth of fifty‐per cent (for example) efficient electrically small dipole antennas can be designed with twice the bandwidth predicted by the Chu lower bound for the quality factor of fifty‐per cent efficient antennas.

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Switching of Reactive Elements in High-Q Antennas

Cited by 25 publications

References 1 publication

Pulse Characteristics of a Direct Antenna Modulation Transmitter

Pulse Characteristics of a Direct Antenna Modulation Transmitter

An Energy-Synchronous Direct Antenna Modulation Method for Phase Shift Keying

Overcoming the Chu lower bound on antenna Q with highly dispersive lossy material

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