Abstract
A non-Foster circuit (NFC) is known as an active broadband matching technique to improve the impedance matching bandwidth of an electrically small antenna (ESA). There has been a vast amount of papers that report the generation of negative impedance using an NFC and its effectiveness on broadband antenna matching. However, only a few discussed its impact on the signal-to-noise-ratio (SNR), which is one of the most important figures-of-merit for a wireless communication system. In this paper, the SNR enhancement due to an NFC was measured and discussed. An NFC was carefully designed to have a low dissipation loss and to meet the stability conditions. The optimized NFC design was fabricated and applied to an ESA length of λ⁄15 at a frequency range of 150 to 300 MHz. The measured results showed that the NFC enhanced the received power of the antenna system by more than 17 dB. However, due to the noise added by the NFC, the SNR enhancement was not guaranteed for some frequency points. Nevertheless, an average of 7.3 dB of SNR improvement over the frequency band of interest is possible based on the experiment result.
Highlights
Due to the noise added by the non-Foster circuit (NFC), the SNR enhancement was not guaranteed for some frequency points
The demand for miniaturized communication systems has tremendously increased for many applications such as mobile devices, medical wearables, military radios and vehicles, etc
A vast amount of research has been conducted on the so-called electrically small antenna (ESA), which is defined by an antenna whose maximum dimension is less than λ/2π [1,2]
Summary
The demand for miniaturized communication systems has tremendously increased for many applications such as mobile devices, medical wearables, military radios and vehicles, etc. The matching bandwidth is extremely narrow, since the passive L, C, and the antenna itself follow the Foster’s reactance theorem [3]. The latter asserts that the reactance must increase as the frequency increases. The ESA’s capacitance is completely cancelled by the inductance at a single frequency, implying the matching Both the C and L increase as the frequency increases, following Foster’s reactance theorem. The operation principle of an NFC is simple, as depicted in non-Foster has circuit matching technique employing active components (e.g., transistor) has been. It generates a broad reactance cancellation bandwidth be achieved. To improve the stability of the of observing the stability condition both frequency and time applied
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