@mytec: iter5 ready for test

frontend/public/workers/rf-worker.js

@@ -42,6 +42,13 @@ self.onmessage = function (e) {
 
 /**
  * Calculate RSRP at a specific point (universal formula)
+ *
+ * RSRP = P_tx + G_tx - FSPL - PatternLoss
+ *
+ * Includes:
+ *  - Antenna gain (site.gain)
+ *  - 3GPP sector pattern with back lobe (no hard cutoff)
+ *  - Radio horizon limit based on antenna height
  */
 function calculatePointRSRP(site, point) {
   var distance = haversineDistance(site.lat, site.lon, point.lat, point.lon);
@@ -49,6 +56,14 @@ function calculatePointRSRP(site, point) {
   // Minimum distance to prevent -Infinity
   if (distance < 0.01) distance = 0.01;
 
+  // Radio horizon check: d_horizon = 3.57 * sqrt(h_meters)
+  // Uses 4/3 Earth radius for standard atmospheric refraction
+  var siteHeight = site.height || 10; // default 10m if missing
+  var horizon = calculateRadioHorizon(siteHeight);
+  if (distance > horizon) {
+    return -Infinity;
+  }
+
   // Free space path loss (universal)
   var fspl =
     20 * Math.log10(distance) + 20 * Math.log10(site.frequency) + 32.45;
@@ -56,31 +71,63 @@ function calculatePointRSRP(site, point) {
   // Link budget: RSRP = P_tx + G_tx - FSPL
   var rsrp = site.power + site.gain - fspl;
 
-  // Apply sector antenna directivity: hard cutoff + gradual pattern loss
+  // Apply 3GPP sector antenna pattern (main lobe + side lobes + back lobe)
+  // No hard cutoff — back lobe is attenuated by front-to-back ratio (~25 dB)
   if (site.antennaType === 'sector' && site.azimuth !== undefined) {
     var bearing = calculateBearing(site.lat, site.lon, point.lat, point.lon);
-    var relativeAngle = Math.abs(bearing - site.azimuth);
-    var normalizedAngle =
-      relativeAngle > 180 ? 360 - relativeAngle : relativeAngle;
-
     var beamwidth = site.beamwidth || 65;
+    var frontBackRatio = 25; // dB, typical for sector panel antennas
 
-    // Hard cutoff: no signal outside beamwidth
-    if (normalizedAngle > beamwidth / 2) {
-      return -Infinity;
-    }
-
-    // Gradual 3GPP pattern loss within beamwidth
-    var patternLoss = calculateSectorPatternLoss(
-      normalizedAngle,
-      beamwidth
+    var patternLoss = calculate3GPPPattern(
+      site.azimuth,
+      bearing,
+      beamwidth,
+      frontBackRatio
     );
-    rsrp -= patternLoss;
+    rsrp -= patternLoss; // patternLoss is positive dB
   }
 
   return rsrp;
 }
 
+/**
+ * Radio horizon distance in km.
+ * d = 3.57 * sqrt(h) where h is antenna height in meters.
+ * Accounts for 4/3 Earth radius (standard atmosphere refraction).
+ */
+function calculateRadioHorizon(heightMeters) {
+  return 3.57 * Math.sqrt(heightMeters);
+}
+
+/**
+ * 3GPP TR 36.814 Horizontal Antenna Pattern.
+ *
+ * A(θ) = min[ 12 * (θ / θ_3dB)², A_m ]
+ *
+ * Returns POSITIVE dB loss value (to be subtracted from RSRP).
+ *
+ * - θ       = angular offset from boresight (0-180°)
+ * - θ_3dB   = half-power beamwidth / 2
+ * - A_m     = maximum attenuation = front-to-back ratio
+ *
+ * At 0°  → 0 dB loss (boresight)
+ * At ±θ_3dB → 3 dB loss (half-power points)
+ * At ±90° → capped at A_m (~25 dB)
+ * At 180° → capped at A_m (~25 dB, back lobe)
+ */
+function calculate3GPPPattern(azimuth, bearing, beamwidth, frontBackRatio) {
+  // Normalize angle difference to -180…+180
+  var angleDiff = bearing - azimuth;
+  while (angleDiff > 180) angleDiff -= 360;
+  while (angleDiff < -180) angleDiff += 360;
+
+  var theta = Math.abs(angleDiff);
+  var theta3dB = beamwidth / 2;
+  var Am = frontBackRatio;
+
+  return Math.min(12 * Math.pow(theta / theta3dB, 2), Am);
+}
+
 /**
  * Haversine distance in km
  */
@@ -116,16 +163,3 @@ function calculateBearing(lat1, lon1, lat2, lon2) {
   var bearing = (Math.atan2(y, x) * 180) / Math.PI;
   return (bearing + 360) % 360;
 }
-
-/**
- * Sector antenna pattern loss (3GPP model)
- */
-function calculateSectorPatternLoss(angleOffBoresight, beamwidth) {
-  var theta3dB = beamwidth / 2;
-  var sideLobeLevel = 20;
-
-  return Math.min(
-    12 * Math.pow(angleOffBoresight / theta3dB, 2),
-    sideLobeLevel
-  );
-}