function?[gammaO2?gammaH2Orange]?=?absorption_range（heightWvd?freqbeta）
%?This?function?computes?the?atmospheric?absorption?as?a?function?of
%?target?height?and?range
%?
%?Inputs
????%?height????==?target?height?array?in?Km
????%?Wvd???????==?water?vapor?density?array?in?g/m^3
????%?freq??????==?radar?operating?frequency?in?Hz
????%?beta??????==?intial?elevation?angle?in?degrees
%
%?Outputs
????%?gammaO2???==?atmospheric?absorption?due?to?oxygen?in?dB
????%?gammaH2O??==?atmospheric?absorption?due?to?water?vapor?in?dB
????%?A_km??????==?atmospheric?absorption?versu?range
%
format?long
ro?=?6375;
v1?=?0.018;
v2?=?.05;
v3?=?0.1;
v4?=?0.3;
lambda?=?3e10/freq;?%?wavelength?in?cm
height?=?height?./1000;
T?=?288?-6.7?.*?height;?%?compute?temperature?array?at?different?heights
pressure?=?1015?.*?（1-0.02275.*height）.^5.2561;%?compute?air?pressure?array?at?different?heights
%?implement?Eq.?（8.115）
P?=?（v1?*?0.4909?.*?pressure.^2）?./?（T.^（5/2））;?
Q?=?v1^2?*?2.904e-4?.*?pressure.^2?./?T;
gammaO2?=?P?.*?（1./（1+Q.*lambda^2））?.*?（1+?（1.39/lambda^2））;
%?implement?Eq.?（8.117）
P?=?1.852?*?3.165e-6?.*?Wvd?.*pressure.^2?./?（T.^（3/2））;
Q1?=?（1?-?0.742?*?lambda）^2;
Q2?=?（1?+?0.742?*?lambda）^2;
Q?=?2.853e-6?.*?pressure.^2?./T;
gammaH2O?=?P?.*（（1./（Q1?+?Q?.*lambda^2））?+?（1./（Q2?+?Q?.*lambda^2））?+?3.43/lambda^2）;
%?convert?beta?into?radian?
beta?=?beta?*?pi?/180.;?
%?calcualte?array?of?r0?plus?target?height
r?=?ro?+?height;
alpha?=asin（cos（beta）?*?ro?./r）;
theta?=?（pi/2）?-?beta?-?alpha;
%?range?=?sqrt（ro^2?+?r.^2?-?2?*?cos（theta）?*?ro?.*?r）;
range?=?r?.*?sin（theta）?/?cos（beta）;?
end