Do I understand it correctly that one of the advantages of (conductor-backed) coplanar waveguide over microstrip is the possibility of making (with a suitable gap) the former narrower than the latter, all other things being equal? (Which is to say, R _c, dielectric thickness and \epsilon _r.)
What'd be the disadvantages? (Other than the need for a lot of vias along the trace and the potentially increased losses precisely due to traces being narrower.)
Trying a few samples with a network analyzer, we've found that a 2.83 mm microstrip (1.5 mm / 36 um FR-4) matches 50 Ohm perfectly. Now, as we go for higher frequencies (from about 50 MHz now towards up to 3 GHz), the design calls for a SPDT signal relay, and HF3, whose specs look rather promising, is apparently designed with a coplanar waveguide in mind, and wouldn't be a good fit for a board employing 2.83 mm microstrips.
(Though, as we've found, the considerably cheaper IM03 works rather well up to 50 MHz or so -- with just such microstrips.)
Any comments on the use of coplanar / HF3 in , perchance? (In particular, is \epsilon _r = 4.6 FR-4 a thing? I've thought it's more like 4.2 to 4.4.)
Thanks in advance.