High-Power Wideband Transmission of Modulated Signals Using an Integrated Class-E Active Electrically-Small Antenna

Core Concepts

The proposed active electrically-small antenna design can radiate wideband HF signals with bandwidths of 24 kHz or more, with total efficiencies up to 80%, and radiated power levels approaching 100 W, by integrating a highly-efficient, class-E switching circuit with the antenna.

Abstract

The content describes the design and experimental characterization of a high-power, active electrically-small antenna (ESA) that can efficiently radiate wideband HF signals with bandwidths of 24 kHz or more. Key highlights: Conventional passively-matched ESAs are fundamentally limited in their bandwidth-efficiency products due to the high quality factor of the antenna. The proposed design integrates a highly-efficient, class-E switching circuit with the ESA to overcome these limitations. In the sub-optimum mode of operation, the class-E amplifier can achieve bandwidths exceeding 100 kHz with efficiencies up to 78%. Experimental results demonstrate the ability to generate binary ASK, PSK, and FSK modulations with bandwidths ≥24 kHz and radiated power levels up to 64 W. The bandwidth-efficiency product of the proposed active antenna is 5.4-9.8 dB higher than that of an equivalent passive design for the same data rate and bit-error-rate. The maximum achievable radiated power level is estimated to be up to 700 W by operating the transistor at its maximum voltage rating.

Stats

Radiated power up to 64 W Efficiency up to 78% Bandwidth exceeding 100 kHz

Quotes

"The proposed active ESA can radiate wideband HF signals with banwidths of 24 kHz or more, with total efficiencies up to 80%, and radiated power levels approaching 100 W." "Experimental results indicate that the bandwidth-efficiency product of this class-E active antenna is 5.4-9.8 dB higher than that of an equivalent passive design with the same data rate, and bit-error-rate (BER)."

Key Insights Distilled From

Class-E, Active Electrically-Small Antenna for High-Power Wideband Transmission at the High-Frequency (HF) Band

by Nathan Strac... at arxiv.org 04-05-2024

https://arxiv.org/pdf/2404.03468.pdf

Deeper Inquiries

How can the proposed active antenna design be further optimized to achieve even higher radiated power levels and bandwidths

To further optimize the proposed active antenna design for higher radiated power levels and bandwidths, several strategies can be implemented. One approach is to enhance the efficiency of the amplifier circuit by reducing losses in the components and improving the matching between the amplifier and the antenna load. This can be achieved by using high-quality components with lower losses and optimizing the impedance matching network. Additionally, increasing the DC supply voltage to the amplifier can boost the radiated power levels, as the radiated power is proportional to the square of the supply voltage. Careful tuning of the bias inductor and the amplifier circuit can also help in achieving higher efficiency and power levels. Moreover, exploring advanced modulation techniques and signal processing algorithms can enable the transmission of higher data rates within the available bandwidth, thereby maximizing the utilization of the active antenna's capabilities.

What are the potential challenges and limitations in scaling this design to higher frequencies beyond the HF band

Scaling the design to higher frequencies beyond the HF band presents several challenges and limitations. One major challenge is the increased reactance of the antenna at higher frequencies, which can lead to impedance mismatch issues and reduced efficiency. The components used in the circuit, such as the transistor and inductors, may exhibit different behaviors at higher frequencies, requiring careful selection and tuning for optimal performance. Additionally, the parasitic elements in the circuit can become more significant at higher frequencies, affecting the overall performance of the active antenna. Another limitation is the availability of components that can operate efficiently at higher frequencies while maintaining the desired power levels and bandwidth. Designing for higher frequencies also requires more stringent RF design considerations and may involve complex electromagnetic simulations to ensure proper functionality and performance.

What other applications beyond HF communications could benefit from the high-power, wideband capabilities of the integrated class-E active antenna

The high-power, wideband capabilities of the integrated class-E active antenna can benefit various applications beyond HF communications. One potential application is in radar systems, where the ability to radiate high power levels over a wide bandwidth can enhance detection and tracking capabilities. The active antenna can also be utilized in wireless power transfer systems, enabling efficient energy transmission over extended distances. In satellite communications, the high-power, wideband transmission capabilities of the active antenna can improve data transfer rates and signal reliability. Furthermore, in scientific research applications such as radio astronomy or ionospheric studies, the active antenna's performance can facilitate the collection of high-quality data over a broad frequency range. Overall, the integrated class-E active antenna has the potential to revolutionize various communication and sensing systems that require high-power, wideband transmission capabilities.