The secret decoder ring:

 

Mode	Uplink	Downlink
Mode A	2m	10m
Mode K	15m	10m
Mode T	15m	2m
Mode J	2m	70cm
Mode B	70cm	2m

 

Mode	Uplink	Downlink
Mode KA	2m *and* 15m	10m
Mode KT	15m	10m *and* 2m

• RS-12/13 (Modes A, K, T, KA, KT–depends on the whim of the "Chief Designer")
• FLASH it appears that RS-12/13 has left us...killed by a solar flare...sad day
  
• RS-15 (Mode A)...Intermittant...I have heard the beacon but never my own downlink (or anyone else's)
• FO-20 and FO-29 (Mode J)
• AO-27 and UO-14 (single-channel FM satellites; both Mode J)
• AO-7!!  Alive again!  Modes A and B, although B seems to be the most common configuration.
  

The beauty about the LEOs is that their orbital altitude is only about 900-1700 km, so a mere 100W ERP and omni antennas will work fine.  The principle limiting factors are receiver sensitivity and the actual antenna pattern(s) realized.

CURRENT LEO STATUS--Click this link to see the LATEST on what's up

 AMSAT-NA Weekly Satellite Report

A distinction of satellite work from HF is that it is "full-duplex".  That is, since two different bands are involved, you can hear yourself sending/talking.  (Split operation is "half-duplex"...the transmit and receive frequencies are different, but you cannot transmit and receive at the same time).  In fact, to tune in another station you HAVE to be able to work full-duplex.  So right off that means--another radio in the truck.  Note that several folks have successfully worked satellites half-duplex, but I think they would admit it's much more difficult that way (but not impossible).

My mobile station already has an FT-100, which will transceive on all these bands.  So by looking at the mode chart, what should the second (CW/SSB) radio be?

1. With another HF-only radio, I could work modes A, K, T, KA, KT                    (RS satellites)
2. With another FT-100 (or a pair of IC-706) I could work all 6 LEO modes!        (RS, FO, and FM satellites)
3. With another 2m all-mode, I could work modes A, T, J, KA, KT.                    (RS except mode-K, FO, and FM)
4. With another 70cm all-mode, I could only work mode J.                                  (FO and FM satellites)

So for option 3 above, I need TX antennas for 15m and 2m, and RX antennas for 10m, 2m, and 70cm.  Being equipped for HF mobile already, the 15m and 10m requirements are already met with the HS-1500 screwdriver.  My initial solution for 2m and 70cm was to use my existing FM dual-band whip, and after some time I migrated to separate 2m and 70cm M2 HO-loops..  With the initial solution you would need a duplexer to split the dual-band antenna out to separate 2m and 70cm ports.

A significant consideration is antenna polarization (linear v. circular).  The FM sats, RS-12/13, and RS-15 are all linearly polarized, while FO-20 and FO-29 use circularly polarized antennas.  Where this makes a difference is that all the LEO satellites "tumble" in their orbits, so that for the linearly polarized ones, the polarization as seen from earth will switch from horizontal to vertical and back (perhaps several times during a pass).  The circularly polarized ones will change "sense" from right-hand to left-hand and back during their passes as well (this is because of the specific design of the circularly polarized antenna on the satellite).

When antenna polarizations don't match, there is additional loss:
 

So what's the best way to minimize the fades?  Well, for the linearly polarized satellites, it's actually best to use a circularly-polarized antenna.  You lose 3dB (from the table) but it's a constant.  For circularly polarized antennas, there are two choices:  (1) use a linear polarized antenna for constant 3dB loss (the opposite of the case for the linearly polarized satellites), or (2) use a circularly polarized antenna with switchable "sense".  There are several ways to go about this, Jerry K5OE has some really great info on how to "roll your own" switchable sense circularly polarized antennas.

There is a bit of additional hardware to consider as well:

• A 2m brick amp would be a useful option to make 100W ERP and easily overcome cable loss etc., but actually is a bit overkill for the LEOs (and too much overkill can damage the satellite!  Be careful!).  In my instance I used a 30Win/160W out amp and adjusted the output of the IC-290H to give me 50W at the antenna input (for approx. 100W ERP, assuming 3dB gain).
• A 2m preamplifier for mode T.  This requirement can be fairly well met if the 2m brick above already has a preamplifier internally.  It's not optimum (lower noise figures and antenna-input mounting are) but given that there isn't a dedicated mode T satellite, it is the most economical route if you decide to go the brick route.  Without a brick/preamp combination, an RF-switching preamp will be needed (to accomodate the fact that 2m can be both an uplink and a downlink).  Mirage and Advanced Receiver Research both make good RF-switching preamps.  Or, you can skip the preamp entirely and accept marginal (or no) Mode T performance.
• A 70cm preamplifier for mode J.  If you want to work this mode, you really have to have the preamplifier.  "It Can Be Done" without one but then you can paint your house with a toothpick too if you want.  The good news is that for mode J the preamp doesn't need to be an RF-switched one; a receive-only model will be fine.
• For Mode J, a desense bandpass filter may (will most likely) be needed for the 70cm receive path.

Since we're not using steerable arrays in mobile satellite work, we don't have to "track" satellites per se.  But we do need to know when they're visible.  There are several tracking programs available that will generate printed lists of AOS (satellite rise) and LOS (satellite set) times, so you know when to operate.  I just print out a list every week for the coming week and keep it in the truck.

LEO Satellite Links and further operating information

 AMSAT-NA  The Mother Ship
 ARRLWeb: Amateur Satellite Communications

 RS-12/13 Operator's Forum
 AC5DK's RS-12/13 page

 K5OE, Eggbeater II Antenna
 ON1CAU Satellite Page

 Nova For Windows  my personal favorite satellite tracking software

 The ABS Pipe Mount--fits in the front of the pickup bed
 The VHF-UHF Lineup...70cm Eggbeater, 6m Halo, 2m HO-Loop  (note the Eggbeater has been replaced with a 70cm HO-loop)