O
oopere
- Jan 1, 1970
- 0
I am playing with two antennas which are know to be useful for sending
and receiving UWB pulses. Essentially I am reproducing the cone and TEM
horn antennas described in http://www.picosecond.com/objects/AN-14a.pdf
Fig.4.
From the time domain S11 parameter of the cone antenna, it follows that
the antenna exhibits a nice resistive impedance until the pulse hits the
end of the cone. Something similar happens with the TEM horn.
I was wondering what would be a good way to "terminate" the cone or the
horn to avoid (or minimize) the reflections from the antenna end.
If I had "ground" nearby, this would be easier.
Do you think I should solder a number (1 every cm) of 0805 resistors
from the cone end to a dummy cone continuation? Perhaps a dummy ring
would suffice? Or better a dummy flat hat?
\ / <- Dummy cone
\ /
R ... R
\ /
\ / <--- "Active" cone
\/
==============
If so, what value should the resistors be?
Would this also work for the TEM horn?
Would it be a better idea to fold back the TEM horn like this?
__
/ /
/ / <- Horn (inclination is excessive in ASCII art)
/ /
R |
=*========== Ground
| <- Coax input
What should be the terminating resistor value?
If no answers are available, any comments are welcome!
Pere
and receiving UWB pulses. Essentially I am reproducing the cone and TEM
horn antennas described in http://www.picosecond.com/objects/AN-14a.pdf
Fig.4.
From the time domain S11 parameter of the cone antenna, it follows that
the antenna exhibits a nice resistive impedance until the pulse hits the
end of the cone. Something similar happens with the TEM horn.
I was wondering what would be a good way to "terminate" the cone or the
horn to avoid (or minimize) the reflections from the antenna end.
If I had "ground" nearby, this would be easier.
Do you think I should solder a number (1 every cm) of 0805 resistors
from the cone end to a dummy cone continuation? Perhaps a dummy ring
would suffice? Or better a dummy flat hat?
\ / <- Dummy cone
\ /
R ... R
\ /
\ / <--- "Active" cone
\/
==============
If so, what value should the resistors be?
Would this also work for the TEM horn?
Would it be a better idea to fold back the TEM horn like this?
__
/ /
/ / <- Horn (inclination is excessive in ASCII art)
/ /
R |
=*========== Ground
| <- Coax input
What should be the terminating resistor value?
If no answers are available, any comments are welcome!
Pere