396 IEEE TRANSACTIONS ON BROADCASTING, VOL. 50, NO. 4, DECEMBER 2004 Height Gain Measurements for DTV Reception in Singapore J. T. Ong, S. V. B. Rao, Yan Hong, and G. Shanmugam Abstract—Very few height-gain measurements have been made especially in built-up areas. Measurements made in Singapore con- firm that the height-gain is different in different locations and de- pends on the local clutter, ground reflection and the radiation pat- tern of the transmitting antenna. In high rise HDB (Housing De- velopment Board) estates, height loss is observed instead of gain. Index Terms—Digital broadcasting, DTV, DVB-T, height gain, radio wave propagation. I. INTRODUCTION I N MOST CITIES, the area covered by the Central Business District (generally the high rise areas) is very small while the area covered by the low-rise (suburban) districts is large. In Singapore, 75% of the population lives in the high-rise (50–60 meters high) housing apartments built by the Housing Develop- ment Board (HDB). The buildings, which are clustered together in large estates, have virtually the same height. The HDB en- vironment occupies about 50% of the built-up areas. This is a hostile environment for the reception of DTV signals. This envi- ronment is quite different from the so called urban environment defined by the ITU-R. One of the important parameters to be monitored is the signal strength at 10 m level. The propagation prediction method of ITU-R P.1546 [1] prescribes a standard receiving antenna height of 10 meters and a correction formula is provided to predict field strength values for different receiving antenna heights in dif- ferent environments. The representative clutter heights used in the recommendations are 20 m for urban and 30 m for dense urban areas. The elevation angle of the arriving ray is also in- cluded in the calculations to estimate the modified representa- tive clutter height, which depends on the height of the transmit- ting antenna and the distance from the transmitting antenna to the mobile unit. Using this recommendation, for a transmitting antenna height of 284 m amsl and at a distance of 9.2 km from the transmitter, it was found that for a dense urban environment, a correction of 33 dB is required at 2 m level. This value is very high when compared to the earlier recommendations at UHF; a height loss of 12 dB is used, based on measurements in Nether- lands [2]. For VHF, a height loss of 10 dB is used, taken from ITU-R 1203 [3]. Chester 97 [4] adopted the ITU-Recommendations [2], [3] and prescribes the minimum required field strength of 65 dB V m at 10 m level for Digital TV reception using a directional antenna for 95% of coverage. However, due to the Manuscript received May 19, 2004; revised June 18, 2004. This work was supported by the Media Development Authority of Singapore (MDA). J. T. Ong, Y. Hong, and G. Shanmugam are with the Positioning and Wireless Technology Centre, Nanyang Technological University, Singapore-637553. S. V. B. Rao was with the Sri Venkateswara University, Tirupati, India and is now with Nanyang Technological University. Digital Object Identifier 10.1109/TBC.2004.837872 introduction of the new ITU-Recommendations [1], there is need to verify Chester 97 recommendations in different clutter types and for Single frequency networks (SFN). If necessary some corrections has to be made in the Chester 97 recom- mendations. However, this can only be done based on some experimental results on height gain. The other important issue is that the urban, and dense urban conditions defined in ITU-R may not applicable to Singapore and probably to other similar cities, where the built areas were covered with high density and high rise buildings. Characterization of signal reception in such environment is required for the future fixed DTV reception. In view of the above observations, the present study is un- dertaken to study the height-gain between 2 and 10 meters high antennas in 14 locations with different clutter types and in 11 locations inside an HDB estate and also signal variation with height (from 3 to 45. meters) in an apartment building for DTV reception in Singapore. Measurements were carried out using different receiving antennas to study the relative change in the received field strength at 2 m and 10 m levels. Results are pre- sented in Section III. II. EXPERIMENTAL DETAILS The measurements were carried out using a Van with a hy- draulic mast, which can be extended to 10 meter level. The field strength values were recorded using R&S EFA receiver for TV Mobile (Ch37, centre frequency 602 MHz). The technology is based on DVB-T, and the configuration is 2 k, QPSK, 1/2; rates, 1/4; guard interval. Omni directional antenna (dual polar with 5 dBi gain), log-periodic directional antenna (6 dBi gain) and 6-element directional Yagi antenna (10 dBi gain) were used to record the field strengths at 2 and 10 m levels in different loca- tions. The locations are selected to cover different clutter types. Measurements carried in 14 locations and inside an HDB estate are presented based on the field strength values recorded at 2 & 10 m levels. The transmitting antenna height is 284 m amsl and there are 10 gap fillers (repeaters) and whole set up operates as single frequency network (SFN). The main transmitting antenna is horizontally polarized, with a very high gain, and provides an effective radiated power (ERP) of 47 Kw. The main beam is down tilted by about 0.7 degrees. The repeaters are vertically polarized and transmit less power, ranging from few watts to 1 Kw e.r.p. III. RESULTS AND DISCUSSIONS Measurements were carried out at 14 locations with different clutter types. These measurements were made at fixed points. A van with hydraulic mast was used. Results of the height gain measurements are shown in Table I. It also provides a brief de- scription about the clutter around the measurement location. It can be observed from these studies that the height gain is 0018-9316/04$20.00 © 2004 IEEE