High Bandwidth Electrically Small Antennas Through BFSK Direct Antenna Modulation

Santos, Jean Paul; Fereidoony, Foad; Huang, Yikun; Wang, Yuanxun Ethan

doi:10.1109/milcom.2018.8599778

Cited by 3 publications

(4 citation statements)

References 9 publications

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“…A reduction in the charging time * is expected to increase the average energy per bit E bavg radiated from the system (and vice versa) [12]. The concept of peak voltage (or current) switching has been described elsewhere [2,6,13,16] but the simple model presented here illuminates important behaviours that arise when switching an antenna synchronously between frequencies, ultimately placing constraints on the frequency separation as will be discussed in later sections.…”

Section: Theory Of Operationmentioning

confidence: 99%

“…Frequency shift keying (FSK) is of particular interest for DAM schemes because it requires the most bandwidth for a given data rate while being relatively energy efficient. While the DAM concept was originally developed for FSK at very low frequency [7][8][9][10][11][12], it was recently rediscovered for higher frequency FSK systems and demonstrated in several different papers [13][14][15][16][17][18]23]. It is mentioned in several prior studies that energy storage and transfer is fundamental to the scheme but a model and quantitative understanding of how energy storage (or lack thereof) affect the signal characteristics has not been investigated in much detail.…”

Section: Introductionmentioning

confidence: 99%

“…As antennas become small relative to a wavelength, their gain-bandwidth product falls cubically [1]; therefore, a broadband signal cannot be transmitted efficiently from a small passive antenna. However, these bandwidth limitations only apply to linear, time-invariant (LTI) systems and time-varying matching or direct antenna modulation (DAM) techniques have been studied to transmit broadband signals from these narrowband antennas for different modulation schemes [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], pulse-based high-Q receivers [19,20], and for the high speed near-field communication (NFC) system [21]. In many cases, these DAM systems have been shown to significantly outperform LTI transmit antennas.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Theory Of Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Transient analysis of dynamically switched frequency shift keyed transmitters

Srivastava

Adams

2022

IET Microwaves Antenna & Prop

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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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