Broadband planar antenna on dielectric half-space

Planar log-periodic (toothed) antennas are a beautiful thing in a free space, but on a dielectric half-space their radiation patterns (not to mention impedance) are very bad, useless I should say.

What kind of (planar or other flat) antenna on (or close to) a dielectric half-space would you recommend? Desired bandwidth 10:1. Application: mm-wave to THz antenna on a semiconductor substrate+lens.

Greetz,
rfmw

well a patch is probablly the best way to go,
but you can use a printed dipole, it has a nice BW.