"Rohit" wrote in message
oups.com...
Hi all,
I have placed 2 similar antennas (3 dB beamwidth = 90deg,
Polarization= LHC) on a PEC box with a small spacing between the 2.
Both antenna's are tilted and the first one is at 45deg and other at
135 deg from the horizontal so that both can cover 180 deg.

With this setup, in the simulation result i am observing heavy
distortion (about 10dB ripple or more) at 90 deg. What is the reason
for this heavy distortion. Is there any way i can remove the
distortion in the pattern without changing the antenna's position??

Thanks in advance,
Rohit


Hi Rohit

I consider your antenna to be one antenna with two driven elements.
Wherever the individual patterns from the elements overlap, they will add or
subtract depending on their relative phase.
Can you consider switching to alternately choose one element or the other?
Can you change the pattern shape so the patterns dont overlap? What are
your choices?

Jerry

Because i need 180 deg coverage i have to use both antennas together.
The 3dB beamwidth of 90deg of both antennas give me 180deg coverage.
And i expect the gain to be 3dB down at 90deg but instead i am getting
gain less by 10 to 15 dB. Is there any way i can get less ripple at
the overlap?

"Rohit" wrote in message
oups.com...
Because i need 180 deg coverage i have to use both antennas together.
The 3dB beamwidth of 90deg of both antennas give me 180deg coverage.
And i expect the gain to be 3dB down at 90deg but instead i am getting
gain less by 10 to 15 dB. Is there any way i can get less ripple at
the overlap?


Hi Rohit

I think this "pattern merging" will become clear to you when you consider
the fact that the signals from each element has equal amplitude at Crossover
(90 degrees). Therefore the signal at that direction will add to twice the
value of either, ir subtract to zero, depending on their phase. That is a
heck of a big difference from In Phase to Out of Phase.

I'd suggest that you include more info about your ultimate goal. There
are some very well informed guys reading this news group who might be
willing to help you.

Jerry