Revise FoV cones for dishes...

[AdmiralTigerclaw]

...Using MATHS.

(Low priority for balancing later. This is not for player-side examination or consumption and should never be forced on them.)

I've been looking around for this and finally found it in my Communications textbook.

Beam Width in degrees from one half power point to the other (AKA: Cone size or 'angle') is 70 times wavelength over mouth diameter of the dish.

Bw° = (70 ƛ) / D

So now we can compute the cone widths of the dishes based on the actual model shapes instead of arbitrary connections. (Assuming this wasn't already done. But I don't know.)

The range of frequencies available to 'choose' from ranges from 136 MHz in the VHF band, all the way to 27 GHz in the Ka band.

Example.

If we take a 8.1 GHz transmission (X Band) and use a 2 meter diameter dish...

(70 * 0.031) / 2 = 1°

If we take 136 MHz from the bottom end of the used range and put it on a 1-meter dish

(70 * 2.205) / 1 = 154.35°

Again, this is from half-power point on one side of the cone to the other half-power point.

It would probably be good to 'pick' a frequency that Kerbals use and use this as the base of the equations. Picking the frequency that's too low results in huge beam cones, while picking one that's too high... Well, see the X band transmission math I pulled out.

In relation, there's also the power gain equation, which is how much power gain you get because of the antenna within the beam width. (Passive gain)

Gain [Power With respect to half-length Dipole antenna] = 6 (D / Wavelength)^2

The example in the textbook shows this produces a 47 dB gain in power along the beam width just from the antenna.

[Starstrider42]

For the record, Cilph said at some point that the original cones were set to have a constant width at maximum range, rather than trying to be realistic. If you do the math (dish diameters are in the online documentation), each antenna does in fact operate at a different frequency.

Likewise, power consumption does not scale with beam attenuation (2π R² (1-cos θ/2) for both dishes and omnis). Otherwise, all dishes would have the same power requirements because of Cilph's criterion, and omnis would need either much larger ranges or much smaller power drains.

But after experimenting with some tweaks along these lines in my main game, I decided that trying to make these parameters realistic would be very hard to balance. And only a communications engineer or an astronomer would ever notice that something was wrong. :wink:

[AdmiralTigerclaw]

Still something to be looked into at some point. It may be hard to balance, but we only have to balance it once. And it's something that can be afforded to take one's time with.