If I really had to could go ultra cheap, vacuum silver metalized / or co pper electroplated ABS plastic is very close to the old Rogers Duroid elect rically
@ 10 Ghz...
Duroid 5880 Er @ 50 Ohms stripline, 2.22 +/- 0.02 Dissipation .0009 @ 10 Ghz
Plated ABS Er @ 50 Ohms stripline, 1.89 to 2.12 Dissipation .0024 @ 1
0 Ghz
It has about 1.5x the expansion coefficient, around one half the specific g ravity, similar mechanical properties under tension/compression but 1/3rd t he heat dissipation and one third the maximum usable temperature. Only prob lem is soldering to it... You would have to wirebond everything and glue th e die down.
But its good for antennas and cheap waveguides, as is a specialized low los s plastic such as PREPERM...
That said, I'd look at ISOLA and the Chinese ISOLA clones. Since LNAs /LNBs sell for next to nothing whatever is used for the LNB is probably the tick et.. This is worth a read for losses due to surface quality, etc..
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There is a very private GHZ and Up RF mailing list I subscribe to, I'll as k what the non ceramic cheap PCB du Jour is...
That should settle this..
Steve