Cross-Polarized Null-Steering in Over-the-Horizon Radar with Planar Monopole Array on Finite Radial Ground Plane

Henault, S.; Morin, G.A.

doi:10.1109/apusncursinrsm.2018.8609423

Cited by 5 publications

(5 citation statements)

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“…In a transmit beamformer where null steering is implemented and radiation is maximized toward a target at ( θ t , ϕ t ), weights or excitations can be determined using

boldw = {R_{x x}}^{- 1} {boldE}_{θ} false(θ_{t}, ϕ_{t} false)

R_{x x} = true \sum_{l = 1}^{L} ((), {boldE}_{θ} false(θ_{l}, ϕ_{l} false) {boldE}_{θ} {false(θ_{l}, ϕ_{l} false)}^{H} + {boldE}_{ϕ} false(θ_{l}, ϕ_{l} false) {boldE}_{ϕ} {false(θ_{l}, ϕ_{l} false)}^{H}) + σ_{o}^{2} I

where θ l and ϕ l are the elevation and azimuth angles of the l th null. As discussed in Henault and Morin (), cross‐polarization needs to be considered, otherwise null depths can degrade due to the finite ground plane of the antenna system. The formulation given in can deal not only with point clutter but also with volumetric or angularly distributed clutter if a suitable number L of nulls cover the entire clutter distribution at sufficient angular intervals.…”

Section: Theorymentioning

confidence: 99%

“…Null steering is inherently very sensitive to antenna calibration accuracy (Henault & Morin, , ), and various calibration error mechanisms must be carefully considered. Calibration refers to the correction of amplitudes and phases of each individual array element in the array.…”

Section: Introductionmentioning

confidence: 99%

“…This investigation attempts to determine the best way to use the 256‐planar monopole array for operation over the entire 3‐ to 18‐MHz band. Significant challenges exist at lower frequencies in a single antenna array covering this whole band due to the limited electrical size with decreasing frequency and increased sensitivity to array calibration errors (Henault & Morin, , ). This paper looks at different calibration error mechanisms and proposes an approach to optimize beamforming performance over the whole band.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of a 256‐Monopole Transmit Antenna Array for Over‐the‐Horizon Radar in Canada

Henault

Riddolls

2019

Radio Science

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A 256‐monopole planar array is investigated as a potential transmit antenna covering the entire 3‐ to 18‐MHz band in an over‐the‐horizon radar (OTHR) operating at high latitudes in Canada. This array is relatively inexpensive, simple to build, and offers the azimuth and elevation resolutions necessary to defeat the auroral clutter which has traditionally limited the operation of OTHR at high latitudes. It is demonstrated that excellent clutter rejection ratios are possible with this antenna array and accurate calibration, but significant performance degradation occurs with calibration errors in particular in the lower portion of the operating frequency band. Various calibration approaches and error mechanisms are studied. A new approach combining multiple‐input‐multiple‐output (MIMO) radar techniques at lower frequencies and conventional transmit null steering at higher frequencies is proposed and evaluated. This approach enhances the robustness of the array to calibration errors while preserving the radar unambiguous range‐Doppler space across the operating frequency band.

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“…In a transmit beamformer where null steering is implemented and radiation is maximized toward a target at ( θ t , ϕ t ), weights or excitations can be determined using

boldw = {R_{x x}}^{- 1} {boldE}_{θ} false(θ_{t}, ϕ_{t} false)

R_{x x} = true \sum_{l = 1}^{L} ((), {boldE}_{θ} false(θ_{l}, ϕ_{l} false) {boldE}_{θ} {false(θ_{l}, ϕ_{l} false)}^{H} + {boldE}_{ϕ} false(θ_{l}, ϕ_{l} false) {boldE}_{ϕ} {false(θ_{l}, ϕ_{l} false)}^{H}) + σ_{o}^{2} I

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of a 256‐Monopole Transmit Antenna Array for Over‐the‐Horizon Radar in Canada

Henault

Riddolls

2019

Radio Science

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“…While a negative SNR is insufficient for target detection, target detection is not the focus of this study. Additionally, real operational scenarios could improve the SNR level for these frequencies by optimizing radar parameters, such as the configuration, number, and power of the transmitter antennas [48], [52], [53]. Some general conclusions can be found from Fig.…”

Section: A Output Of the Environmental Monitor Including The Output F...mentioning

confidence: 92%

“…In the future, a spread Doppler clutter model should be added to this FMS's SNR calculation. Other transmitter antenna configurations and power are being tested with the FMS, such as a 16 by 16 array with 256 monopoles [52], [53].…”

Section: Limitations and Future Workmentioning

confidence: 99%

Frequency Management System (FMS) for Over-the-Horizon Radar (OTHR) Using a Near-Real-Time Ionospheric Model

Thayaparan

Villeneuve

Themens

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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Sky-wave over-the-horizon radar (OTHR) propagates radio waves off the ionosphere to provide long-range surveillance around the Earth's curvature. Frequency selection for high-latitude and polar OTHRs is challenging unless there is an environmental monitor that addresses the significant ionospheric variability in high-latitude regions, a spectrum monitor that finds unoccupied frequencies in the high-frequency (HF) radio waveband, and a frequency management system (FMS) that selects an optimal frequency from the merged results of the environmental monitor and spectrum monitor. This article describes the first FMS for high-latitude OTHR that merges results from the environmental monitor and spectrum monitor in realtime. The environmental monitor uses the assimilative Canadian high-arctic ionospheric model (A-CHAIM), which assimilates near-real-time data and is, to date, the most advanced ionospheric model for high-latitude regions. Despite remaining limitations, demonstrations of this real-time FMS between a transmitter and four targets during the day and night and during fall and summer show that it could be one of the tools for selecting frequencies for operational scenarios.

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Using MIMO to Extend the Operating Band of Over-the-Horizon Radar Transmit Beamformers to Lower Frequencies

Henault

2019

2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting

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Cross-Polarized Null-Steering in Over-the-Horizon Radar with Planar Monopole Array on Finite Radial Ground Plane

Cited by 5 publications

References 4 publications

Investigation of a 256‐Monopole Transmit Antenna Array for Over‐the‐Horizon Radar in Canada

Investigation of a 256‐Monopole Transmit Antenna Array for Over‐the‐Horizon Radar in Canada

Frequency Management System (FMS) for Over-the-Horizon Radar (OTHR) Using a Near-Real-Time Ionospheric Model

Using MIMO to Extend the Operating Band of Over-the-Horizon Radar Transmit Beamformers to Lower Frequencies

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