OldskoolPirate wrote: ↑
Mon May 20, 2019 4:58 pm
What would you recommend for that setup then Albert ?
It depends on the coverage they're trying to attain. It also is affected by their permitted radiated power. The Lindenblad is supposed to provide "mixed" or "circular" polarisation to the signal, and be omni-directional. Circular polarisation was used by the early commercial FM stations as it was thought to penetrate city buildings better, and be less prone to multipath distortion - at least that was the claim of the manufacturers of these over-priced slightly radiating dummy loads.....
If they are supposed to have coverage that's in one direction from their site, then they can use directional aerials like "H"s which give hemispherical radiation, or three element Yagis if they need a more restricted beam angle. If they want mixed polarisation, they can use an "X-Y" Yagi (constructed for horizontal and vertical operation), and with the use of a phasing harness, they could put spin on the signal and go circular....
If their coverage is to be omnidirectional, then a J-pole or a Slim Jim are good choices. Either gives a marginal gain over a dipole, and are easy to match. A friend of mine in Egypt developed the "MSJ" (Modified Slim Jim) for high sites. The feedpoint is moved up the aerial (to a second resonant point) were the aerial still appears to be 50Ω, but the radiation angle droops - great for a high site that needs very local coverage.
Of course they could try the trick a friend of mine used on his 25W RSL station. When it was inspected, it was running into a J-pole. When the inspector left site, they added the top two sections to the antenna, turning it into a version of the "Super-J" colinear!!! Their ERP quadrupled.