I am not a fan of omni antennas for the current LEO satellites. The eggbeater or moxons are marginal performers at best.
Short, quality feedlines and RX preamps are good ways to minimize ineffectiveness of omnis but there’s no silver bullet.
If you have no other choice but omnis, you may find yourself limited to certain satellites** and certain passes. SO-50, for example, is not going to be favorable. Compensating for lack of hearing ability by running full power won’t make you many friends.
Working satellites on an almost daily basis, one can often identify an eggbeater or omni user by their inability to hear a very strong signal from the satellite. Usually these operators have a strong signal but can’t hear themselves or another strong station calling them.
A set of small yagis at a fixed elevation with an azimuth rotor will yield far better results. The trick is not using longer, high-gain yagis. You’ll have more beam width with smaller ones. Considering what many stations achieve with an Arrow or Elk antenna (7,000+ km contacts,) bigger isn’t always better.
- Omnis are okay as long as you understand the shortcomings.
- You may make some contacts with omnis. Try it but don’t invest much money or effort into them.
- Omnis are an okay choice if you have no other option but to eliminate the need for a rotor. I realize sometimes there are operational constraints.
- Don’t expect consistent AOS to LOS performance with an omni unless you have a great view of the horizon and sky in all directions and a very low-noise RF environment.
** The best satellites for omni’s are likely going to be mode B (U/V) SSB transponders like AO-73, XW-2A, XW-2C, XW-2F. AO-7 will be okay at times depending on health and elevation of pass. FO-29 will be marginal if you pick the right passes.