Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Sidelobe reduction with a GaN active array antenna

Abstract: This work proposes a tunable sidelobe reduction method based on a GaN active-antenna technique, in which the output radio frequency power is controlled by the DC drain voltage of the amplifiers. In this study, a 1 × 4 array of active antenna with GaN amplifiers is designed and fabricated. GaN amplifiers capable of up to 10 W-class power output are fabricated and arranged for a four-way active-array antenna. The fabricated single-stage GaN amplifier offers a maximum power-added efficiency of 59.6% and a maximum output power of 39.3 dBm. The maximum output power is decreased to 36.5 dBm upon decreasing the operating drain voltage from 55 to 35 V. In this study, a 4.5 dB sidelobe reduction is demonstrated in a 1 × 4 active antenna based on this output power difference for each amplifier.

Active antenna phase modulator performance

Abstract: This paper demonstrates experimental and simulated evidence on the extent to which an active microstrip antenna consisting of a rectangular patch radiator peripherally loaded with a GaAs MESFET can be operated as a phase modulator. The results given illustrate that phase modulation can be obtained by applying a variable DC bias to the active antenna in the presence of an injection locking signal. It is shown that the injection locking signal can be applied at the fundamental, second harmonic or at subharmonic frequencies. The pushing characteristics of the active antenna module, together with phase modulation plots and circuit/device sensitivity to injection locking signal magnitude are presented.

Effective Sensitivity of A Non-uniform Phased Array of Short Dipoles

Abstract: Short dipoles are a key element in new low frequency array antennas as proposed for LOFAR and other astronomical applications. Unfortunately standard texts on short dipole antennas are based on the effective area and do not lead to an astronomically useful sensitivity formulation in a straightforward manner. The concept of maximum effective area is applied to arrays of short dipoles and allows expressing the sensitivity as the ratio of this area over the effective sky brightness temperature as long as the output noise power is dominated by the antenna input radiation. For both quantities we only need to know the array directivity pattern that includes the mutual coupling effects when the actual loading conditions of the array elements are taken into account. Short dipole elements have a constant directivity pattern for frequencies below resonance, but they exhibit strong complex impedance variations that provide only narrow band performance when power matching is applied as required in transmit applications. However, in receive applications voltage or current sensing can be realized, for example with an active balun. Assisted by the steep increase of the sky brightness with wavelength for frequencies below 300 MHz, this can provide sky noise dominated performance over at least a three to one frequency range. Still the low frequency limit is determined by the amplifier noise contribution and the losses in the antenna and in the dielectric ground surrounding the elements. We show that for a sparse array with the elements non-uniformly distributed according to an exponential shell model, a constant sensitivity can be obtained over a frequency range of at least two octaves. In addition, such a configuration has a factor of six greater sensitivity than a rectangular array for a large part of the frequency band.

Gain-enhanced distributed amplifier-based CRLH-leaky wave antenna for quasi-resonant power recycling scheme

Abstract: A distributed amplifier combined with CRLH-leaky wave antennas (LWAs) for a new resonant type power recycling scheme is proposed. By connecting a closed loop to the LWA on the drain side of the distributed amplifier, we can obtain gain enhancement compared to the one directly terminated without the loop. Such enhancement fluctuates with respect to the frequency. At some specific frequencies, the enhancement reaches a maximum. The phenomenon will be explained theoretically and validated through the measurement and simulation in this paper.

Calibration Proposal for New Antenna Array Architectures and Technologies for Space Communications

Abstract: In large antenna arrays with a large number of antenna elements, the required number of measurements for the characterization of the antenna array is very demanding in cost and time. This letter presents a new offline calibration process for active antenna arrays that reduces the number of measurements by subarray-level characterization. This letter embraces measurements, characterization, and calibration as a global procedure assessing about the most adequate calibration technique and computing of compensation matrices. The procedure has been fully validated with measurements of a 45-element triangular panel array designed for Low Earth Orbit (LEO) satellite tracking that compensates the degradation due to gain and phase imbalances and mutual coupling.