Part 2.  
  This can be employed in two ways: 1. Increasing and 2. Decreasing reflection.  
  Increased reflection.  
  The H2S was a far cry from a hi-resolution radar by to-days standards, but it provided the navigator with a picture of sufficient fidelity to distinguish between surfaces of low reflection (water and other smooth flat surfaces) and high-reflection objects like buildings.  The H2S was used for two purposes: To navigate through radar significant waypoints typically with a good land-water contrast and to identify the aim-point.  It is well described in the literature how radar reflectors (Tarnkörper) were positioned on lakes and rivers in larger German towns in order to remove the radar contrast between the water on the surroundings.  This makes identification of the aim-point difficult if not impossible.  



Shapes used in German corner reflectors.


Modern corner reflector.



A "textbook" example of a H2S display in 20 NM sweep, with a map of the area covered.  The antenna must be set a a fairly high depression angle, judging from the large ground echo in the center.  Additionally the receiver gain must be turned somewhat down in order to produce a clean picture with no clutter and clear returns from built-up areas.

  As previously described Pathfinders distributed in the Stream would navigate to the waypoints, drop a Skymarker and the following bombers would steer for the marker.  When attacking targets in the Baltic or the Northern part of Central Germany the stream was frequently routed through Denmark and Sweden [sic]!  The Danish west coast is not abundant with good radar way points.  Basically there are only those 4 locations indicated on the map below, and accordingly these were used to make landfall.  If the land-water contrast has been eliminated by radar reflectors, the navigator will not get the radar return he expects, as the bomber approaches the coast line.  This would probably result in an interesting conversation between the plane captain and the navigator.  The crew might change course in order to get the way-point on the H2S screen, or they might decide to press on, and drop their marker as they cross the coastline.  Problem was, the crew was unsure about their position, and they were dropping a marker, which the succeeding 50 bombers relied upon for navigation.  
  Probably in an attempt to increase/change the shape of the coastline at Thyborön, a number of corner reflectors were positioned on the water in the fjord east of the coastline.  See illustration below.   
  Map from resistance movement report.  The annotation to the 7 squares in the upper right translates:  "Camouflage objects tethered on shallow water"; no doubt German corner reflectors codenamed TRIBERGE.  There is no information indicating a similar arrangement at Ringkøbing Fjord, but at Esbjerg there is a note in a Kriegsmarine Kriegs Tage Buch (KTB) from January 1944:  "Counter measures implemented against the Rotterdam Gerät [H2S] through deployment of "camouflage objects" (Tarnkörper).  Camouflage of Esbjerg and Hansted initiated.  Work in progress".  See German text below.  

Extract from Adm.Däne KTB, January 1944 ! (sic).

  Part 3.