Changed to a direct set of the ModuleDataTransmitter packetSize and packetResourceCost instead of our previous attempt at a dynamic overload that wasn't working.
Changed to a direct set of the ModuleDataTransmitter packetSize and packetResourceCost instead of our previous attempt at a dynamic overload that wasn't working.

It seems to be working now!

file:b/AntennaRange.cfg (new)
--- /dev/null
+++ b/AntennaRange.cfg
@@ -1,1 +1,50 @@
+//

+// AntennaRange © 2013 toadicus

+// 

+// This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a

+// copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/

+//

+// This software uses the ModuleManager library © 2013 ialdabaoth, used under a Creative Commons Attribution-ShareAlike

+// 3.0 Uported License.

+//

+// Specifications:

+// nominalRange:	The distance from Kerbin at which the antenna will perform exactly as prescribed by packetResourceCost

+// 					and packetSize.

+// maxPowerFactor:	The multiplier on packetResourceCost that defines the maximum power output of the antenna.  When the

+//					power cost exceeds packetResourceCost * maxPowerFactor, transmission will fail.

+// maxDataFactor:	The multipler on packetSize that defines the maximum data bandwidth of the antenna.

+// 

+

+@PART[longAntenna]

+{

+	@MODULE[ModuleDataTransmitter]

+	{

+		@name = ModuleLimitedDataTransmitter

+		nominalRange = 1500000

+		maxPowerFactor = 8

+		maxDataFactor = 4

+	}

+}

+

+@PART[mediumDishAntenna]

+{

+	@MODULE[ModuleDataTransmitter]

+	{

+		@name = ModuleLimitedDataTransmitter

+		nominalRange = 30000000

+		maxPowerFactor = 8

+		maxDataFactor = 4

+	}

+}

+

+@PART[commDish]

+{

+	@MODULE[ModuleDataTransmitter]

+	{

+		@name = ModuleLimitedDataTransmitter

+		nominalRange = 80000000000

+		maxPowerFactor = 8

+		maxDataFactor = 4

+	}

+}

 

--- a/AntennaRange.cs
+++ b/AntennaRange.cs
@@ -1,128 +1,183 @@
+/*

+ * AntennaRange © 2013 toadicus

+ * 

+ * AntennaRange provides incentive and requirements for the use of the various antenna parts.

+ * Nominally, the breakdown is as follows:

+ * 

+ *     Communotron 16 - Suitable up to Kerbalsynchronous Orbit

+ *     Comms DTS-M1 - Suitable throughout the Kerbin subsystem

+ *     Communotron 88-88 - Suitable throughout the Kerbol system.

+ * 

+ * This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a

+ * copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/

+ * 

+ * This software uses the ModuleManager library © 2013 ialdabaoth, used under a Creative Commons Attribution-ShareAlike 3.0 Uported License.

+ * 

+ */

+

 using System;

-using System.Linq;

 using System.Collections.Generic;

 using KSP;

 

 namespace AntennaRange

 {

+	/*

+	 * ModuleLimitedDataTransmitter is designed as a drop-in replacement for ModuleDataTransmitter, and handles range-

+	 * finding, power scaling, and data scaling for antennas during science transmission.  Its functionality varies with

+	 * three tunables: nominalRange, maxPowerFactor, and maxDataFactor, set in .cfg files.

+	 * 

+	 * In general, the scaling functions assume the following relation:

+	 * 

+	 *     D² α P/R,

+	 * 

+	 * where D is the total transmission distance, P is the transmission power, and R is the data rate.

+	 * 

+	 * */

 	public class ModuleLimitedDataTransmitter : ModuleDataTransmitter, IScienceDataTransmitter

 	{

+		// Stores the packetResourceCost as defined in the .cfg file.

 		protected float _basepacketResourceCost;

+

+		// Stores the packetSize as defined in the .cfg file.

 		protected float _basepacketSize;

+

+		// We don't have a Bard, so we're hiding Kerbin here.

 		protected CelestialBody _Kerbin;

 

-		public float KSCantennaGain = 1f;

-

+		// Returns the current distance to the center of Kerbin, which is totally where the Kerbals keep their radioes.

 		protected double transmitDistance

 		{

 			get

 			{

 				Vector3d KerbinPos = this._Kerbin.position;

-

 				Vector3d ActivePos = base.vessel.GetWorldPos3D();

 

 				return (ActivePos - KerbinPos).magnitude;

 			}

 		}

 

+		// Returns the maximum distance this module can transmit

 		public double maxTransmitDistance

 		{

 			get

 			{

-				return Math.Sqrt (this.maxAntennaPower / this._basepacketResourceCost * this.antennaGain * this.KSCantennaGain) * this.optimalRange;

-			}

-		}

-

+				return Math.Sqrt (this.maxPowerFactor) * this.nominalRange;

+			}

+		}

+

+		// The distance from Kerbin at which the antenna will perform exactly as prescribed by packetResourceCost

+		// and packetSize.

 		[KSPField(isPersistant = false)]

-		public double optimalRange;

-

+		public double nominalRange = 1500000d;

+

+		// The multiplier on packetResourceCost that defines the maximum power output of the antenna.  When the power

+		// cost exceeds packetResourceCost * maxPowerFactor, transmission will fail.

 		[KSPField(isPersistant = false)]

-		public float maxAntennaPower;

-

+		public float maxPowerFactor = 8f;

+

+		// The multipler on packetSize that defines the maximum data bandwidth of the antenna.

 		[KSPField(isPersistant = false)]

-		public float antennaGain = 1f;

-

-		[KSPField(isPersistant = false)]

-		public new float packetSize

-		{

-			get

-			{

-				if (this.transmitDistance >= this.optimalRange)

+		public float maxDataFactor = 4f;

+

+		// Build ALL the objects.

+		public ModuleLimitedDataTransmitter () : base() { }

+

+		public override void OnStart (StartState state)

+		{

+			base.OnStart (state);

+

+			if (state >= StartState.PreLaunch && this._Kerbin == null)

+			{

+				// Go fetch Kerbin, because it is tricksy and hides from us.

+				List<CelestialBody> bodies = FlightGlobals.Bodies;

+

+				foreach (CelestialBody body in bodies)

 				{

-					return this._basepacketSize * this.antennaGain * this.KSCantennaGain;

+					if (body.name == "Kerbin")

+					{

+						this._Kerbin = body;

+						break;

+					}

 				}

-				else

-				{

-					return this._basepacketSize * (float)Math.Pow (this.optimalRange / this.transmitDistance, 2) * this.antennaGain * this.KSCantennaGain;

-				}

-			}

-			set

-			{

-				this._basepacketSize = value / (this.antennaGain * this.KSCantennaGain);

-			}

-			

-		}

-

-		[KSPField(isPersistant = false)]

-		public new float packetResourceCost

-		{

-			get

-			{

-				if (this.transmitDistance <= this.optimalRange)

-				{

-					return this._basepacketResourceCost / (this.antennaGain * this.KSCantennaGain);

-				}

-				else

-				{

-					return this._basepacketResourceCost * (float)Math.Pow (this.transmitDistance / this.optimalRange, 2) / (this.antennaGain * this.KSCantennaGain);

-				}

-			}

-			set

-			{

-				this._basepacketResourceCost = value * (this.antennaGain * this.KSCantennaGain);

-			}

-

-		}

-

-		public ModuleLimitedDataTransmitter () : base()

-		{

-			List<CelestialBody> bodies = FlightGlobals.Bodies;

-

-			foreach (CelestialBody body in bodies)

-			{

-				if (body.name == "Kerbin")

-				{

-					this._Kerbin = body;

-					break;

-				}

-			}

-		}

-

+			}

+		}

+

+		public override void OnLoad(ConfigNode node)

+		{

+			base.OnLoad (node);

+			this._basepacketSize = base.packetSize;

+			this._basepacketResourceCost = base.packetResourceCost;

+		}

+

+		// Post an error in the communication messages describing the reason transmission has failed.  Currently there

+		// is only one reason for this.

 		protected void PostCannotTransmitError()

 		{

-			string ErrorText = String.Format ("Unable to transmit: out of range!  Maximum range = {0}; Current range = {1}.", this.maxTransmitDistance, this.transmitDistance);

+			string ErrorText = string.Format (

+				"Unable to transmit: out of range!  Maximum range = {0}; Current range = {1}.",

+				this.maxTransmitDistance,

+				this.transmitDistance);

 			ScreenMessages.PostScreenMessage (new ScreenMessage (ErrorText, 4f, ScreenMessageStyle.UPPER_LEFT));

 		}

 

+		protected void PreTransmit_SetPacketResourceCost()

+		{

+			if (this.transmitDistance <= this.nominalRange)

+			{

+				base.packetResourceCost = this._basepacketResourceCost;

+			}

+			else

+			{

+				base.packetResourceCost = this._basepacketResourceCost

+					* (float)Math.Pow (this.transmitDistance / this.nominalRange, 2);

+			}

+		}

+

+		protected void PreTransmit_SetPacketSize()

+		{

+			if (this.transmitDistance >= this.nominalRange)

+			{

+				base.packetSize = this._basepacketSize;

+			}

+			else

+			{

+				base.packetSize = Math.Min (

+					this._basepacketSize * (float)Math.Pow (this.nominalRange / this.transmitDistance, 2),

+					this._basepacketSize * this.maxDataFactor);

+			}

+		}

+

+		// Override ModuleDataTransmitter.GetInfo to add nominal and maximum range to the VAB description.

 		public override string GetInfo()

 		{

 			string text = base.GetInfo();

-			text += "Optimal Range: " + this.optimalRange.ToString() + "\n";

+			text += "Nominal Range: " + this.nominalRange.ToString() + "\n";

 			text += "Maximum Range: " + this.maxTransmitDistance.ToString() + "\n";

 			return text;

 		}

 

+		// Override ModuleDataTransmitter.CanTransmit to return false when transmission is not possible.

 		public new bool CanTransmit()

 		{

-			if (this.packetResourceCost > this.maxAntennaPower)

+			if (this.transmitDistance > this.maxTransmitDistance)

 			{

 				return false;

 			}

 			return true;

 		}

 

+		// Override ModuleDataTransmitter.TransmitData to check against CanTransmit and fail out when CanTransmit

+		// returns false.

 		public new void TransmitData(List<ScienceData> dataQueue)

 		{

+			PreTransmit_SetPacketSize ();

+			PreTransmit_SetPacketResourceCost ();

+

+			Tools.PostDebugMessage (

+				"distance: " + this.transmitDistance

+				+ " packetSize: " + this.packetSize

+				+ " packetResourceCost: " + this.packetResourceCost

+			);

 			if (this.CanTransmit())

 			{

 				base.TransmitData(dataQueue);

@@ -133,8 +188,18 @@
 			}

 		}

 

+		// Override ModuleDataTransmitter.StartTransmission to check against CanTransmit and fail out when CanTransmit

+		// returns false.

 		public new void StartTransmission()

 		{

+			PreTransmit_SetPacketSize ();

+			PreTransmit_SetPacketResourceCost ();

+

+			Tools.PostDebugMessage (

+				"distance: " + this.transmitDistance

+				+ " packetSize: " + this.packetSize

+				+ " packetResourceCost: " + this.packetResourceCost

+				);

 			if (this.CanTransmit())

 			{

 				base.StartTransmission();

@@ -143,6 +208,47 @@
 			{

 				this.PostCannotTransmitError ();

 			}

+		}

+

+		#if DEBUG

+		[KSPEvent (guiName = "Show Debug Info", active = true, guiActive = true)]

+		public void DebugInfo()

+		{

+			PreTransmit_SetPacketSize ();

+			PreTransmit_SetPacketResourceCost ();

+

+			string msg = string.Format(

+				"'{0}'\n" + 

+				"_basepacketSize: {1}\n" +

+				"packetSize: {2}\n" +

+				"_basepacketResourceCost: {3}\n" +

+				"packetResourceCost: {4}\n" +

+				"maxTransmitDistance: {5}\n" +

+				"transmitDistance: {6}\n" +

+				"nominalRange: {7}\n" +

+				"CanTransmit: {8}",

+				this.name,

+				this._basepacketSize,

+				base.packetSize,

+				this._basepacketResourceCost,

+				base.packetResourceCost,

+				this.maxTransmitDistance,

+				this.transmitDistance,

+				this.nominalRange,

+				this.CanTransmit()

+				);

+			ScreenMessages.PostScreenMessage (new ScreenMessage (msg, 30f, ScreenMessageStyle.UPPER_RIGHT));

+		}

+		#endif

+	}

+

+	public static class Tools

+	{

+		[System.Diagnostics.Conditional("DEBUG")]

+		public static void PostDebugMessage(string Str)

+		{

+			ScreenMessage Message = new ScreenMessage (Str, 4f, ScreenMessageStyle.UPPER_RIGHT);

+			ScreenMessages.PostScreenMessage (Message);

 		}

 	}

 }