Azimuthal Variation of Measured HF Noise

Posa, Leonard M.; Materazzi, Daniel J.; Gerson, N. C.

doi:10.1109/temc.1972.303201

Cited by 4 publications

(4 citation statements)

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“…Investigation into the use of arrays of active antennas could further improve the SNR and at the same time reduce cochannel interference by the suppression of signals arriving at lower elevation angles in NVIS reception, as was shown in Section 4.3. Measurements that provide insight in the spatial distribution of ambient noise arriving via skywave, similar to those reported in [18,19], are helpful input to optimize this aspect of receive antennas. For the same reason, ambient noise measurements in Europe to update ITU-R Recommendation P.372 [16] with more recent man-made noise levels are planned.…”

Section: Topics For Further Researchmentioning

confidence: 87%

“…As the levels of man-made noise are highly dependent on electric and electronic equipment quality, equipment density, and geographical distribution, and while these parameters have changed over time, new HF noise measurement campaigns using modern means [17] are desirable. Interesting studies show the nonuniform azimuthal distribution of noise [18,19], which is important for the understanding of HF receive antenna signal-to-noise performance.…”

Section: Nvis Receptionmentioning

confidence: 99%

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Near Vertical Incidence Skywave Propagation: Elevation Angles and Optimum Antenna Height for Horizontal Dipole Antennas

Witvliet

Maanen

Petersen

et al. 2015

IEEE Antennas Propag. Mag.

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Near Vertical Incidence Skywave (NVIS) communication uses the ionosphere as a reflector to cover a continuous area with a radius of at least 150 km around the transmitter, on frequencies typically between 3 and 10 MHz. In developing countries, in areas lacking any other telecommunication infrastructure, it is used on a daily basis for voice and data communication. It may also be used in ad-hoc emergency (disaster) communication in other regions. This paper proposes optimum heights above ground for horizontal dipole antennas for NVIS, based on simulations and empirical data. First, the relationship between elevation angle and skip distance is obtained using ionospheric ray tracing. The high elevation angles found by simulation are confirmed by elevation angle measurements using a professional radio direction finder. The measurements also show the dominance of NVIS over ground wave propagation starting at a short distance. For these elevation angles, the optimum receive and transmit antenna heights above ground are derived using antenna simulations. A distinction is made between optimum transmit signal strength and optimum received signal-to-noise ratio (SNR). These optima are verified experimentally, demonstrating a novel evaluation method that can be used in the presence of the fading typical for ionospheric propagation. For farmland soil ( % 20 mS/m, " r % 17) the optimum height above ground for the transmit antenna is 0.18-0.22. If the antenna is lowered to 0.02 a transmit signal loss of 12 dB occurs. This corresponds with the theory. The receive antenna height, however, while appearing uncritical in the simulations, showed a clear optimum at 0.16 and a 2-7 dB SNR deterioration when lowered to 0.02.

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Section: Topics For Further Researchmentioning

confidence: 87%

Section: Nvis Receptionmentioning

confidence: 99%

Near Vertical Incidence Skywave Propagation: Elevation Angles and Optimum Antenna Height for Horizontal Dipole Antennas

Witvliet

Maanen

Petersen

et al. 2015

IEEE Antennas Propag. Mag.

View full text Add to dashboard Cite

show abstract

“…More measurements that provide insight in the spatial distribution of ambient noise arriving via skywave, similar to those reported in [Posa, et al, 1972;Coleman, 2002], would provide valuable input to optimize this aspect of receive antennas. Similarly, measurements on the propagation of man-made noise from individual sources to the receiver, including skywave, would be helpful to establish a correct picture of the origin of its component and their spatial parameters.…”

Section: Radio Noisementioning

confidence: 85%

“…As the levels of man-made noise are highly dependent on electric and electronic equipment quality, equipment density and geographical distribution, and while the latter have changed over time, new HF noise measurements campaigns using modern means [Van Maanen, 2006] are desirable. Interesting studies show the non-uniform azimuthal distribution of noise [Posa, 1972;Coleman, 2002], which is important for the understanding of HF receive antenna signal-tonoise performance. The central topic of this chapter is the optimization of transmit and receive antennas for fixed or temporary base stations that use NVIS radio wave propagation.…”

Section: Nvis Receptionmentioning

confidence: 99%