Antena reach to other planet

[KerbolExplorer]

So im having this problem

I need to sent a probe to Moho in carrer but i dont exacly know what antena to put on the probe

So can somebody say how many G`s are from Kerbin to other planets in the sistem

thanks in advanced

[mk1980]

take a look at the wiki page here:

https://wiki.kerbalspaceprogram.com/wiki/Kerbol_System

the image "Orbits of planets and dwarf planets" should solve your question.

According to that image Moho orbit is (roughly) between 4-6 Gm from the sun and kerbin is about ~13 Gm. An antenna with ~19 Gm range should be enough to reach your probe even when Moho and Kerbin are on opposite sides of the sun.

[Superfluous J]

You can get the limits in the game too. Go into map mode and select a planet (Moho) and you'll see it's Pe and Ap markers. Then check out Kerbin's as well. You'll see the values that mk1980 said above.

[Deddly]

Question about gameplay moved to Gameplay Questions

[ThreePounds]

@mk1980 has already provided a really good answer but I thought I'd follow this up with a precise measurement over the course of little over five kerbin years. In this diagram, I've plotted the distance between Kerbin and all the inner planets and Dres. As you can get from a glance, Moho is never further than 2.00E+07km away. 

The exact numbers are as follows:

Distance between Kerbin and Moho

Minimum Distance	7.29E+06km
Maximum Distance	1.99E+07km

According to the wiki to span the distance of 2E+07km, or 20Gm, you either need a 15G antenna paired with a lvl2 tracking station, a 2G antenna paired with a lvl3 tracking station, two 100G antennas talking to each other or a 15G antenna talking to a 100G antenna. Or anything better.

[Kryxal]

Also note that if you've increased the difficulty, it may have decreased the effective range.

[ThreePounds]

1 hour ago, Kryxal said:

Also note that if you've increased the difficulty, it may have decreased the effective range.

Oh yeah, you're absolutely right. I have uploaded a spreadsheet that calculates the maximum distance of any given connection. There is a multiplier field for both sides that can take those values specified by the difficulty setting.

https://docs.google.com/spreadsheets/d/1PLS1UkVRR-qqUluIlyEweaqRFZqAJjp4sLgIiixqdFY/edit?usp=sheets_home

[Snark]

On 9/4/2017 at 1:25 AM, KerbolExplorer said:

So can somebody say how many G`s are from Kerbin to other planets in the sistem

It's a good, simple question, but unfortunately the answer is one of those "it depends" things.

Useful discussion is here:

https://wiki.kerbalspaceprogram.com/wiki/CommNet

...if you'd like the verbose Snark-take on this, read on. 

The detailed blow-by-blow is below, but if you'd like to skip all the nattering and just answer the "never mind the math, what darn antennas do I need to go to Moho?" question, you can just skip straight to the end.

 

On 9/4/2017 at 2:38 AM, mk1980 said:

According to that image Moho orbit is (roughly) between 4-6 Gm from the sun and kerbin is about ~13 Gm.

^This.  Which means that the farthest apart Kerbin and Moho ever get is about 19 Gm.

However,

On 9/4/2017 at 2:38 AM, mk1980 said:

An antenna with ~19 Gm range should be enough to reach your probe

^ here's the rub.  This statement is correct, as far as it goes... but matters are a little more complex than it implies.  The reason is that "How far can I communicate" depends on the power at both ends of the connection.

That is, let's say you want to talk to something that's 19 Gm away (e.g. from Kerbin to Moho, at their greatest separation).  You would need an antenna with a power of 19G... if you had the SAME antenna at both ends.  That is, if you had a 19G antenna on your probe out at Moho, you would also need a 19G antenna back at Kerbin to talk to it.

But if the Kerbin-side antenna is more (or less) powerful than 19G, then your probe antenna would need to be less (or more) powerful, accordingly.

Here's how it works:  distance = sqrt(power1 * power2), where power1 and power2 are the antennas on the two sides of the connection.

Or, another way to put it is, "if I have a ship with power1, and it's some distance away from me, how much power2 do I have to have here?"  And the answer would be, power2 = distance² / power1.

So, let's see how much antenna power you'd have to have on your Moho probe, if it's talking to KSC.  The antenna power of KSC depends on your upgrade level of the tracking station.  It's 10G at level 1, 50G at level 2, and 250G at level 3.

So,

• Tracking station level 1:  (19G)² / 10G = 36G power needed on probe.
• Tracking station level 2:  (19G)² / 50G = 7.22G power needed on probe.
• Tracking station level 3:  (19G)² / 250G = 1.44G power needed on probe.

So, that tells you how much antenna power you need.  So, how to get that much power?  How many of what kind of antennas?

"How many" matters, because most antennas are stackable.  Most of them "stack" with a combinability exponent of 0.75:  that is, if you have N antennas and each one has power P_antenna, then your overall antenna power for the ship P_total = P_antenna * N^0.75.  Or, put another way:  "I need a certain P_total, so how many antennas of power P_antenna do I need to get that?"  And the answer would be, N = (P_total / P_antenna)^1.333.

(Obligatory caveat:  There are some exceptions.  The Communotron-16S doesn't stack at all.  And the Communotron-16 stacks linearly, i.e. if you have 10 of them then you have 10 times the power.  And if you stack antennas that have different power levels, then the formula gets complicated.  But you're not going to be using the Communotron-16S or Communotron-16 for interplanetary communications, so we can set those aside for purposes of this discussion.  And every single stock antenna except those two has the default exponent of 0.75, so let's go with that.  0.75 is also what you'll usually get from modded antennas, unless the mod author has taken the trouble to specifically assign some other exponent to the antenna.)

 

The bottom line:  What antennas do I need on my probe so I can go to Moho?

Depends on your tracking station.

• Tracking station level 1:  You need 36G power on the probe.  You can get that from a single tier-5 antenna (Communotron 88-88, RA-100), or by stacking four tier-4 antennas (HG-55, RA-15).
• Tracking station level 2:  You need 7.22G power on the probe.  You can get that from a single tier-4 antenna (HG-55, RA-15) or by stacking six tier-3 antennas (DTS-M1, RA-2).
• Tracking station level 3:  You need 1.44G power on the probe.  You can get that from a single tier-3 antenna (DTS-M1, RA-2).  (Technically, you could also do it by stacking tier-2 antennas, but since you'd need 1902 of them-- that's right, nearly two thousand-- I won't bother suggesting it.) 

The above assumes that you have a default difficulty setting.  It also assumes that your probe is talking straight to the tracking station.  If you're using a relay, you'd need to plug in the relay's strength instead of the tracking station's, in the above calculations.