 express the free-space loss as just 40 log dm (dm is distance in meters). 18.3.2.2 The Okumura Model. Okumura et al. (Ref. 3) carried out a detailed anal- ysis for path predictions around Tokyo for mobile terminals. Hata (Ref. 4) published an empirical formula based on Okumura's results to predict path loss. The Okumura/Hata model is probably one of the most widely applied path loss models in the world for cellular application. The formula and its application follow. Ldb = 69.55 + 26.16 log f - 13.82 log h - A(hr) + (44.9 - 6.55 log ht) log d, (18.1) CELLULAR AND PCS RADIO SYSTEMS where r is between 150 MHz and 1500 MHz, ht is between 30 m and 300 m, and d is the path distance and is between 1 km and 20 km. A(hr) is the correction factor for mobile antenna height and is computed as follows: For a small- or medium-size city, A(hr) = (1.1 log f - 0.7)hr - (1.56 log f - 0.8) (dB), (18.2a) where hr is between 1 and 10 m. For a large city, A(hr) = 3.2[log(11.75h,)]2 - 4.97(dB), (18.2b) where f > 400 MHz. Example. Let f = 900 MHz, ht = 40 m, hr = 5 m, and d = 10 km. Calculate A(hr) for a medium-size city. A(hr) = 12.75 - 3.8 = 8.95 dB Ldb = 69.55 + 72.28 - 22.14 - 8.95 + 34.4 = 145.15 dB. 18.3.2.3 Building Penetration. For a modern multistory office building at 864 and 1728 MHz, transmission loss (LdB) includes a value for clutter loss L(v) and is expressed as follows: Ldb = L(v) + 20 log d + nfaf + nwaw, (18.3) where the attenuation in decibels of the floors and walls was af and aw, and the number of floors and walls along the line d were Nf and nw, respectively. The values of L(v) at 864 MHz and 1728 MHz were 32 dB and 38 dB, with standard deviations of 3 dB and 4 dB, respectively (Ref. 2). Another source (Ref. 5) provided the following information: At 1650 MHz the floor loss factor was 14 dB, while the wall losses were 3-4 dB for double plasterboard and 7-9 dB for breeze block or brick. The parameter L(v) was 29 dB. When the propagation frequency was 900 MHz, the first floor factor was 12 dB and L(v) was 23 dB. The