Longley Rice propagation model and reciprocity

Code snippet below seems to show that MATLAB's Longley-Rice propagation model may not always be reciprocal - is this correct? Thanks!

close all; clear all;
% A test to show that the Matlab LR functions don't seem to be reciprocal
pm   = propagationModel('longley-rice','AntennaPolarization','vertical');
freq =                  469e6;     % Tx freq (MHz) 
S1   = [39.420200,-82.875300];     % Lat/Lon of Site 1
S2   = [39.413000,-82.896111];     % Lat/Lon of Site 2
s1ht =                   1:50;     % Antenna height @ site 1
s2ht =                   2.08;     % Antenna height @ site 2
% Link from S1 to S2
tx   = txsite('Latitude',S1(1),'Longitude',S1(2),'AntennaHeight',s1ht,'TransmitterFrequency',freq);
rx   = rxsite('Latitude',S2(1),'Longitude',S2(2),'AntennaHeight',s2ht);
PL1  = pathloss(pm,rx,tx);

% Now reverse the link
tx   = txsite('Latitude',S2(1),'Longitude',S2(2),'AntennaHeight',s2ht,'TransmitterFrequency',freq);
rx   = rxsite('Latitude',S1(1),'Longitude',S1(2),'AntennaHeight',s1ht);
PL2  = pathloss(pm,rx,tx);

plot(PL1,s1ht,'linewidth',2); set(gca,'Xdir','Reverse'); set(gca,'Fontsize',20); xlabel('Path loss (dB)'); ylabel('Tx Antenna height (m)')
hold on
grid on
plot(PL2,s1ht,'x','linewidth',2);
legend('S1 to S2','S2 to S1')

[Joel Johnson]

I subsequently noticed that there is no difference in the two in R2021b so probably this got fixed somewhere between R2018 and R2021.

Answer 1

[Tanmay Das]

Hi,

As pointed out by Joel, the bug has been fixed in the future releases. So it is recommended to update the MATLAB version in order to leverage its full functionality.

[Joel Johnson]

Thanks!