Four (4) Important News in Rec. ITU-R P.1546-5

Rec. ITU‑R P.1546 is a notorious radiowave propagation model, used for point-to-area predictions for frequency and network planning of terrestrial services in the frequency range 30 MHz to 3 000 MHz. The latest version of this recommendation can be found here: http://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.1546-5-201309-I!!PDF-E.pdf

The first version of Rec. ITU‑R P.1546 was approved already in October 2001. The recommendation has then been updated continuously and the latest version Rec. ITU‑R P.1546‑5 was approved by ITU (International Telecommunication Union) in September 2013.
This blog post will present four (4) important news in Rec. ITU‑R P.1546‑5. A number of comparisons to its previous version, Rec. ITU‑R P.1546‑4 which was approved in October 2009, will also be presented.

Calculation procedure for distances less than 1 km (Changed)

The calculation procedure for distances less than 1 km between the transmitting and receiving antenna has been changed in Rec. ITU‑R P.1546‑5. In Figure 1 the field strength values are presented for both Rec. ITU‑R P.1546‑4 and Rec. ITU‑R P.1546‑5, for an all land path in the distance range 0.1‑250 meter. The field strength values are calculated for a frequency of 600 MHz, 50% of time, and a transmitting and receiving antenna height above ground level of 150 meter and 10 meter respectively. We can clearly see that for short distances there are large discrepancies in field strengths between Rec. ITU‑R P.1546‑4 and Rec. ITU‑R P.1546‑5. At the unreasonable short distance of only 0.1 meter, the deviation is as great as 42.9 dB. The differences then decline rapidly but at 150 meters the deviation is still as large as 2.7 dB.

Figure 1: Calculated field strength values using both Rec. ITU‑R P.1546‑4 and Rec. ITU‑R P.1546‑5, for an all land path in the distance range 0.1‑250 meter, at a frequency of 600 MHz, 50% of time, where transmitting and receiving antenna height above ground level are 150 meter and 10 meter respectively.

Correction for clutter shielding the transmitting antenna (New)

Correction for clutter shielding the transmitting antenna is a new feature in Rec. ITU‑R P.1546‑5. In Figure 2 the cluttered transmitter correction is presented for a transmitting antenna height above ground level range of 1‑35 meter, and at a frequency of 600 MHz, and for three different clutter heights above ground level in the vicinity of the transmitting antenna.

Figure 2: Cluttered transmitter correction for a transmitting antenna height above ground level range of 1‑35 meter, at a frequency of 600 MHz, and for three different clutter heights (R1) above ground level in the vicinity of the transmitting antenna.

Correction for difference in height between transmitting and receiving antenna (New)

Correction for difference in height between transmitting and receiving antenna is a new feature in Rec. ITU‑R P.1546‑5. In Figure 3 the antenna height difference corrections are presented for a horizontal distance range of 0.1‑1.5 km between transmitting and receiving antenna, and for five different transmitting antenna heights above ground level, where receiving antenna height above ground level is 10 meter.

Figure 3: Antenna height difference corrections, for a horizontal distance range of 0.1‑1.5 km between transmitting and receiving antenna, and for five different transmitting antenna heights above ground level (ha), where receiving antenna height above ground level is 10 meter.

Correction for short paths in urban and suburban environments have been removed (Removed)

Correction for short paths in urban and suburban environments has been removed in Rec. ITU‑R P.1546‑5. In Figure 4 the correction for short urban and suburban paths is presented for a horizontal distance range of 0.1‑14.9 km, at a frequency of 600 MHz, for three different transmitting antenna heights above ground level, and where ground cover surrounding receiving antenna is 10 meter.

Figure 4: Correction for short urban and suburban paths at a frequency of 600 MHz, for three different transmitting antenna heights above ground level (ha), where ground cover surrounding receiving antenna is 10 meter.

–

Thank you for reading this article regarding Four (4) Important News in Rec. ITU‑R P.1546‑5. Please share and comment. All feedback is welcome!