a 2.5 epsilon r substrat ?!

ptfe epsilonr

Hi all;

I'm designing a tapered slot antenna, and some one gave me a substrate with epsilon r = 2.5, h=0.35 mm,t= 17 micron, does this substrate exist?

the frequency is 5 to 15 Ghz , is this dielectric acceptable for this design?

thx.

you can check with substrate manufactureres specially rogeres.
but your data is not like the common substrates.

He gave you that substrate? – then apparently exists …
Joke aside; there is no problem with that value of the dielectric constant or the thickness.
For example see some substrates from Rogers that come very close
http://www.rogerscorporation.com/mwu/pdf/5000data.pdf
epsilon is 2.33, thickness can be 0.35mm or even thinner and 17 microns of copper it is the standard ½ oz, some versions of PTFE have eps=2.5
Is it good for your design? Look at the loss also – tan delta, preferably below 0.005
However, your thickness seem to be to big for your highest frequency of 15GHz, you can have significant excitation of surface waves, see the paper by Pozar attached or the tapered slot papers also attached. This energy coupled to surface waves can adversely affect your radiation pattern.
You could still use it if you cut out the dielectric in the taper region or create holes in the dielectric EBG style (see the papers)
Best if you do some simulations to see if the results are acceptable for you with this thickness with or without the extra measures.
Isn’t your frequency range a little too large? How are you going to feed and match the antenna?




RIGOROUS CLOSED-FORM EXPRESSIONS FOR THE SURFACE WAVE LOSS OF PRINTED ANTENNAS
D. M. POZAR
ELECTRONICS LETTERS 21st June 1990 Vol. 26 No. 13



The Tapered Slot Antenna-A New Integrated Element for Millimeter-Wave Applications
IEEE TRANSACTIONS ON MTT. VOI.. 37. NO. 2. Feb l989
K. SIGFRID YNGVESSON, T. L. KORZENIOWSKI, YOUNG-SIK KIM,
ERIK L. KOLLBERG. AND JOAKIM F. JOHANSSON


IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 47, NO. 8, AUGUST 1999
Millimeter-Wave Tapered-Slot Antennas on Synthesized Low Permittivity Substrates
Jeremy B. Muldavin, and Gabriel M. Rebeiz,

Hi all,

thx fekete for your help, I agree with you that this bandwidth is large but I have a paper containing a microstrip to slotline transition wich have less then 1.5 vswr between 2-18Ghz but with a 10 epsilonr substrate. I'm trying to simulate a transtion with 2.5 epsilonr substrate by the tang delta =0.0009.
aze