A few more things at a higher level (make sure you read the previous post, though):
1. The most important result may be for mini-BUDs. If you have enough signal but can't get a good lock because of an adjacent orbital position that has an interfering transponder, this technique with two small antennas might be as or more effective than a larger dish. As the reference points out, canceling undesirable signals is less critical than combining them. See this graph. With two dishes and 20 degrees of mismatch, one has a cancelation potential of 12-16 dB. That's more than big FTA dishes can do at 2 degrees. Gain matching only needs to be very coarse for this to work, which means it might never have to be adjusted.
2. For anyone stuck with 90 cm antennas because of HOA/municipal rules, you could get the equivalent of a 1.27 m antenna with two 90 cm and a 1.8 m antenna with four 90 cm (best case, somewhat less in reality). Perhaps the threat of this might persuade the HOA to grant an exception to their policy. If not, do it.
3. To clarify what I meant by a true PLL LNB, you need something that will phase lock to an external frequency reference. An example would be the Norsat 3000X series for C-band. They are not free and this makes a case for a rotor/corotor. I did find this for $370. Don't get a plain PLL LNB because it will be useless.
1. The most important result may be for mini-BUDs. If you have enough signal but can't get a good lock because of an adjacent orbital position that has an interfering transponder, this technique with two small antennas might be as or more effective than a larger dish. As the reference points out, canceling undesirable signals is less critical than combining them. See this graph. With two dishes and 20 degrees of mismatch, one has a cancelation potential of 12-16 dB. That's more than big FTA dishes can do at 2 degrees. Gain matching only needs to be very coarse for this to work, which means it might never have to be adjusted.
2. For anyone stuck with 90 cm antennas because of HOA/municipal rules, you could get the equivalent of a 1.27 m antenna with two 90 cm and a 1.8 m antenna with four 90 cm (best case, somewhat less in reality). Perhaps the threat of this might persuade the HOA to grant an exception to their policy. If not, do it.
3. To clarify what I meant by a true PLL LNB, you need something that will phase lock to an external frequency reference. An example would be the Norsat 3000X series for C-band. They are not free and this makes a case for a rotor/corotor. I did find this for $370. Don't get a plain PLL LNB because it will be useless.
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