Maybe just have different axis for each radar. There are a few ways, but tiledlayout is easiest:
heatvals = rand(4,40); % random data for 1 radar
% labels with prefix
y_labels = split(num2str(1:4));
y_labels = strcat('Target',{' '}, y_labels);
% tiledlayout with tight spacing
tlo = tiledlayout(2,1,'TileSpacing','tight');
% using imagesc to show colormaped data
h(1)=nexttile(tlo);
imagesc(heatvals)
yticklabels(y_labels)
xticklabels([]); % hide xlabels here
ylabel('Radar1')
h(2)=nexttile(tlo); % for radar2
imagesc(heatvals);
yticklabels(y_labels)
ylabel('Radar2')
% same colormap for the tiles
cb = colorbar;
set(h, 'Colormap', flipud(hot), 'CLim', [0 1])
cb.Layout.Tile = 'east';
