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

Schab, Kurt; Huang, Danyang; Adams, Jack A.

doi:10.1109/ojap.2020.2972842

Cited by 10 publications

(5 citation statements)

References 17 publications

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“…Curves are shown in Fig. 6 illustrating the efficiency ratios in (5) for two bandwidths B 0 using tuning elements defined by a realistic frequency dependent Q-factor for air-coil inductors [14], [24] Q L = 150 ω/(2π • 30 • 10 6 ).…”

Section: Driven Wire Dipolementioning

confidence: 99%

“…Notably, direct antenna modulation (DAM) techniques based on the energy-synchronous modulation of time-varying components have been proposed, simulated, and measured as viable strategies for exceeding the conventional bandwidth-efficiency product limitations of small antennas, e.g., the Chu limit [1]. Energy-synchronous DAM methods in the literature are typically specific to a signal type and antenna topology, with examples including on-off-keying for dipoles [2]- [4], phase-shift-keying for dipoles [5], and frequency shift keying on small loops [6], [7]. A theme common across these methods is the use of a time-varying matching network (varying on time scales much less than the carrier period) to impress broadband radiating currents onto the LTI portion of the antenna (e.g., metallic areas supporting conduction currents), thereby bypassing the filtering effects of the LTI radiator's impedance bandwidth.…”

Section: Introductionmentioning

confidence: 99%

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Radiation Efficiency Limits in Direct Antenna Modulation Transmitters

Schab

2020

Antennas Wirel. Propag. Lett.

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Relative bounds on radiation efficiency are established for time-modulated antenna systems where radiation is generated by broadband conduction currents impressed using idealized non-radiating time-varying subsystems, such as those found in direct antenna modulation (DAM) transmitters. Analytical and numerical examples demonstrate that the condition of quasi-resonance, common in nearly all practical direct antenna modulation transmitters, imposes severe restrictions on the otherwise unbounded gains in effective efficiency theoretically achievable by this class of time-modulated transmitters.

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Section: Driven Wire Dipolementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radiation Efficiency Limits in Direct Antenna Modulation Transmitters

Schab

2020

Antennas Wirel. Propag. Lett.

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“…In other words, depending on the type of modulation used (e.g., amplitude, frequency, or phase keying) the electromagnetic fields, currents, and voltages are forced to be the same as the steady‐state conditions in the upcoming state. For example, for on‐off keying this involves holding reactive energy on the antenna during the non‐radiating state [6], and in phase‐shift keying this requires very brief periods of energy storage that realign the phase of the antenna's oscillation [22].…”

Section: Introductionmentioning

confidence: 99%

Transient analysis of dynamically switched frequency shift keyed transmitters

Srivastava

Adams

2022

IET Microwaves Antenna & Prop

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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.

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“…The basis of DAM overcomes the high Q-factor of ESAs traditionally limited by linear time invariant (LTI) matching circuits through time-varying operation. The time-varying operation enables the RF energy on the antenna to be directly modulated through the direct integration of switching circuits on an ESA, which enables transmission of highbandwidth signals such as amplitude shift keyed [9,[11][12][13][14][15][16][17], phase shift keyed [18,19] and frequency shift keyed (FSK) [10,[20][21][22][23][24][25][26][27][28][29] signals.…”

Section: Introductionmentioning

confidence: 99%

Onto a higher power handling for very high frequency direct antenna modulation

Santos

Bhakta

Fereidoony

et al. 2022

IET Circuits, Devices & Syst

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Antennas constrained to platforms that require miniaturisation, significantly smaller than the wavelength of the desired frequency, are inefficient radiators and limited to narrowband operations. To overcome these limitations, a technique called direct antenna modulation (DAM), is incorporated with electrically small antennas to enable transmission of high-bandwidth signals through narrowband antennas. DAM utilises switching circuitry to directly modulate the antenna at its corresponding peak energy moments all while being synchronised to the input signal, yet previous iterations were susceptible to low transmit powers due to limitations in the switching network's power handling capability and tremendous coupling between transistor ports that results in an ambiguous switching signal at the gate. A frequency shift keyed (FSK) DAM antenna topology is proposed, which is capable of high-power transmission through a geometrically symmetrical switching circuitry integrating pairs of complementary GaN transistors. The symmetry assists in removing coupling among transistor ports to effectively switch the transistors OFF and ON without regard to the input RF power. The authors' theoretical analysis agrees with our simulations and far-field measurements which show the FSK DAM antenna topology is capable of transmit powers up to −1 dBm given a 42 dBm of input RF power.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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

Cited by 10 publications

References 17 publications

Radiation Efficiency Limits in Direct Antenna Modulation Transmitters

Radiation Efficiency Limits in Direct Antenna Modulation Transmitters

Transient analysis of dynamically switched frequency shift keyed transmitters

Onto a higher power handling for very high frequency direct antenna modulation

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