1. Rainer Grosskopf Institut für Rundfunktechnik GmbH
Propagation Considerations Overview of the activities within Task Group 6/8 BR Information Meeting on RRC-04/05
Rainer Grosskopf
Institut für Rundfunktechnik GmbH

2. Propagation Considerations
History
Recommendation ITU-R P.1546
Propagation curves for non-European areas
Requirements for terrain data
Receiving antenna height loss correction
Miscellaneous
Conclusions

3. Introduction
It seemed to be a simple task to provide propagation information for the planning to be undertaken by the RRC 04/05
There is just one ITU-R-Recommendation dealing with propagation for terrestrial point-to-area services in the frequency range 30 MHz to 3GHz
Recommendation ITU-R P (replacing former Recs. 370, 529, 1146)
Unfortunately the Task Group 6/8 did not fully support that idea

4. History Chairman’s Report, Doc. 14 (Jan 2002)
The recommended point-to-area prediction method for the planning to be undertaken by the RRC is Recommendation ITU-R P Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz
Task Group 6/8 is of the opinion that this will be a satisfactory basis for developing a plan by the Conference

5. History Chairman’s Report, Doc. 142 (July 2003)
The currently recommended point-to-area prediction method for the planning to be undertaken by the RRC is Recommendation ITU-R P Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz
Task Group 6/8 is of the opinion that this will be a satisfactory basis for developing a plan by the Conference

6. History But life was not as easy as it looks like
Some countries and/or delegates wished to use
the former Rec. 370
the GE89 curves for their regions (Africa)
curves based on former Rec. 370 for T-DAB planning in Band III (CEPT)
Rec only in Band V
path specific methods with terrain profile data

7. History Unfortunately there are still some anomalies in Rec. 1546
WP 3K is aware of the problem and works to solve it
The main problem is the mixed land-sea path approach
WP 3K tried to avoid the mixed land-sea path anomaly (unphysical recovery effect) in former Rec. 370
But new anomalies were built in by the new approach
Unfortunately there are still some anomalies in Rec. 1546
(also in former Rec but nobody cares)

8. Recommendation ITU-R P.1546
Extended range of applicability :
All frequencies between 30 to 3000 MHz
Distances between 1 to 1000 km
All time percentages between 1% and 50%
New curves for 10 m and 20 m transmitting antenna height h1
Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz

9. Recommendation ITU-R P.1546
Curves are considered applicable in temperate climates
Variation of field strength with distance is to a large extent controlled by the vertical refractivity gradient
Rec. 453 contains global database of the vertical refractivity gradients dN in N-units/km in the lowest 65 m of the atmosphere (in electronic form)
Applicable for all climatic regions of the world :

10. Recommendation ITU-R P.453
dN values for 1 % of time

11. Recommendation ITU-R P.1546
The field strength curves of Rec are considered to represent temperate climate with a reference value of gradient dN0 , e.g.
dN0= / / N-units/km for 50/ 10/ 1 % of time
For a different radio-climatic region of the world, calculate the difference in gradient  = dN0 – dN
 is used to adjust curves for other climatic regions

12. Curves for non-European areas
Propagation curves are needed for regions prone to extreme super-refractivity and ducting
To get a consistent set of propagation curves for various climatic regions it is advisable to use only one method
Rec.1546 provides a procedure to extend the applicability of the field strength curves for various regions of the world
This procedure was used to derive propagation curves for the geographical zones defined in Geneva 89

13. Curves for non-European areas
dN-values were chosen in a way to fit the curves based on Rec.1546 as good as possible to the original curves of GE89
Parameters used to derive the new curves based on Rec.1546 for various climatic zones are
Description of the geographical zones in GE89
Path type
Refractivity gradient
Effective transmitting antenna height

14. Curves for non-European areas
Geographical division of the planning area into propagation zones
GE89

15. Curves for non-European areas

16. Curves for non-European areas
GE89 curves can be reproduced, largely, using the procedures for modifying the temperate zone curves found in Rec.1546
Necessary to adopt somewhat extreme values of dN (Rec.453)
However, recent measurements in the Gulf area indicate:
dN  –2000 for 1 % of time (-1780 lowest value in Rec. 453)
The values of dN can be widely variable in any climatic zone
RRC may find it advisable to recommend appropriate refractive index lapse rates as parameters in Rec.1546 for each Zone

17. Requirements for terrain data
Rec.1546 can be used with or without terrain height data
Worldwide terrain data (~1 km) are available: GLOBE
Due to the increase in computation time it is not practical to use terrain data in the context of RRC calculations
Detailed prediction methods can be used on a bilateral or multilateral agreement or for coverage area calculations
Higher resolution of terrain data (~100 m) necessary

18. Requirements for terrain data
Not intended to use TCA-correction in RRC calculations
heff values should be provided by administrations
Terrain data could be used to provide heff values
Ground cover data (urban, open) not necessarily needed
Type of propagation path, such as land, sea or mixed land-sea paths can be derived from digital maps, such as IDWM
Information on cold sea/warm sea divisions and geographic data for other propagation areas are needed

19. Receiving antenna height loss correction
For planning purposes the ground cover at rx is not known
Receiving antenna at 10 m in open area is assumed
Height loss correction for a receiving height of 1.5 m a.g.l.
Height loss from 10 m to 1.5 m is approximately:
13 dB at VHF and 16 dB at UHF (Rec. 1546, former 370)
For planning purposes, other values may be used
In bilateral negotiations when the ground cover type is known, the height loss correction formula may be used (Rec.1546)

20. Miscellaneous Several subsections did not cause much discussion
Mixed paths over Zones of different propagation characteristics
Prediction of wanted and unwanted signal levels
Location statistics
Propagation information for shared services

21. Conclusions Most discussions were on choice of prediction method
Final decision will be made at first session of RRC in 2004
Factors influencing the choice of a prediction method
Impact on existing plans
Usage of various methods may be confusing
Desirable to have one single method for the whole planning area and for all frequency bands
 Rec.1546
However, Rec.1546 has still some anomalies

22. Conclusions Alternative methods in the Report to RRC are:
Recommendation ITU-R P.1546
Curves based on Rec.1546 for various climatic zones
Former Recommendation ITU-R P.370 (used for ST61)
GE89 curves based on former Rec.370 (derived and used for the planning in the African Broadcasting Area)
VHF curves based on former Rec.370 (derived and used for T-DAB allotment planning in Wiesbaden 95

23. Conclusions Further alternative:
There is still a lack of propagation data in some parts of the planning area affected by ducting phenomena (e.g. the Gulf, the Red Sea and the East Mediterranean area)
If any new reliable data for those areas show anomalies with the prediction methods used by the Conference
Propagation predictions for requirements affected are to be re-calculated and the matter dealt with as the RRC decides

24. Acknowledgement
I would like to thank all participants of TG 6/8 and WP 3K for their contributions and fruitful discussions
Good luck to WP 3K in November
Good luck to all those who will participate in the first session of the RRC in 2004
- and make wise decisions