 which the antenna is placed is such that dm-d is an odd multiple of the half-wavelength. On the receiving side, a combiner is used that combines the signals received from the two antennas, thereby increasing the signal level. The outage probability of such a system can be calculated as in the following steps: 1. Calculate the multipath activity factor n: n=1-e-0.2(Po)075 (3.57)* where P = Pw/100 is the multipath occurrence factor corresponding to the percentage of the time Pw (%) of exceeding A = 0 dB in the average worst month, as calculated in Equation (3.39). 2. Calculate the nonselective outage: Pns==pw/100 (3.58)* 3. Calculate the square of the nonselective correlation coefficient kns from (3.59)* where the improvement Ins can be evaluated from Equation (3.54) for a fade depth A (dB) correspond- ing to the flat fade margin F (dB) and Pns from the equation above. 4. Calculate the square of the selective correlation coefficient ks from for r w 0 0.5 for 0.5 < r   0.9628 (3.60)* for r w > 0.9628 Microwave Propagation where the correlation coefficient rw of the relative amplitudes is given by (3.61)* for k2 < 0.26 5. Calculate the nonselective outage probability Pdns from (3.62)* where Pns is the nonprotected outage given by the equation above. 6. Calculate the selective outage probability Pds from (3.63)* where Ps is the outage due to selective fading as calculated in Equation (3.51). 7. Calculate the total outage probability Pd as follows: (3.64)* The process to calculate the probability of outage in the frequency diversity scheme of things is similar to the above except that the improvement factor due to frequency diversity is considered. The improvement due to frequency diversity is calculated as (3.65)* where of : frequency separation (GHz) f = carrier frequency (GHz) F = flat fade margin For angle diversity, the process is as follows: 1. Estimate the average angle of arrival Mo from MO = 2.89 X 10-5 Gmd deg (3.66)* where Gm m is the average value of the refractivity gradient (N unit/km). When a strong gro