Frequency-diverse multimode millimetre-wave constant-ϵr lens-loaded cavity

Abstract

This paper presents a physical frequency-diverse multimode lens-loaded cavity, designed and used for the purpose of the direction of arrival (DoA) estimation in millimetre-wave frequency bands for 5G and beyond. The multi-mode mechanism is realized using an electrically-large cavity, generating spatio-temporally incoherent radiation masks leveraging the frequency-diversity principle. It has been shown for the first time that by placing a spherical constant dielectric lens (constant-ϵr) in front of the radiating aperture of the cavity, the spatial incoherence of the radiation modes can be enhanced. The lens-loaded cavity requires only a single lens and output port, making the hardware development much simpler and cost-effective compared to conventional DoA estimators where multiple antennas and receivers are classically required. Using the lens-loaded architecture, an increase of up to 6 dB is achieved in the peak gain of the synthesized quasi-random sampling bases from the frequency-diverse cavity. Despite the fact that the practical frequency-diverse cavity uses a limited subset of quasi-orthogonal modes below the upper bound limit of the number of theoretical modes, it is shown that the proposed lens-loaded cavity is capable of accurate DoA estimation. This is achieved thanks to the sufficient orthogonality of the leveraged modes and to the presence of the spherical constant-ϵr lens which increases the signal-to-noise ratio (SNR) of the received signal. Experimental results are shown to verify the proposed approach.

Lens-Loaded Cavity Antenna With Detector Diode as a Direction-of-Arrival Estimator

“…The randomly oriented scatterer produces enough disorder in the chaotic cavity that for a specific fabricated lens-loaded cavity, the quasi-random radiation modes are very subjective and device specific. A detailed explanation of the construction of the lens-loaded cavity and rationale behind the use of the lens can be found in [16]. The estimator module in Fig.…”

“…One of the main drawbacks of the aforementioned studied techniques is their reliance on a high bandwidth. In this contribution, we show that DoA estimation is possible using significantly less bandwidth compared to computational techniques proposed in [15] and [16]. This is made possible using the proposed estimation technique which exploits the classical concept of power detection to translate the DoA information at the output of a lens-loaded cavity antenna into a detectable voltage.…”

“…However, this was limited by the use of a hypothetical frequency-diverse antenna with high-Q factor. In [16], a numerical and experimental validation of DoA estimation using a lens-loaded cavity aperture was presented. These works use computational methods for the DoA estimation.…”

Millimeter-wave Channel Sounding Technique Using Oversized Lens–loaded Cavity

“…This is true for a radiating wall backed by an over-sized cavity with sub-wavelength holes, also referred to as metasurface in computational imaging literature [6]. When excited from the input of the cavity, the metasurface radiates spatially orthogonal fields that can illuminate a coverage area, while quasi-randomness of the cavity provides bases for encoding the back-scattered data [8,9]. Fig.…”

“…1 to built the lens loaded mode-mixing cavity. Further details on the cavity structure can be found from [9].…”