antenna-theory.com

[4sshol3e]

Hi all!

Can somebody help me?
I have got an asigment at college to design in HFSS UWB antenna that covers 3 bandwidths:

450MHz - 830 MHz
800 MHz - 970 MHz
1800 MHz - 1900 MHz.

Can anybody help me or point me in the right way?
I'm new at this and don't know anything about it...
All i can find is antenna that covers 1 bandwidth.

Thank you!

[helix]

were you given no other constraints (i.e., size, pattern, polarization, efficiency?)

two of your bands are cell phone bands. but obtaining 450-830MHz operation with any kind of decent radiation efficiency and impedance match is going to be just about impossible in a hand-held device.

look up chu's limit on electrically small antennas, it says that the minimum antenna Q = 1/(ka)^3 + 1/(ka) where k is the wave number and a is the radius of the minimum sized sphere bounding your antenna geometry. the fractional 3dB impedance BW is approximately 1/Q.

[4sshol3e]

no, i haven't.
it is just to theoretically process uwb antennas and choose one to make.
430-830 MHz iz DVBT frequency i think.
this two bands (450-830 and 870-900) are overlapping. should i consider it as one bandwidth? 450-900 MHz?

[hagster]

There are various ultra wide band antennas on the Antenna Theory site that you could try.

http://www.antenna-theory.com/antennas/wideband/log-periodic.php

http://www.antenna-theory.com/antennas/aperture/vivaldi.php

http://www.antenna-theory.com/m/antennas/travelling/spiral.php

[4sshol3e]

thank you

[helix]

yeah you have a lot of options if there's no other requirements!! the types suggested by hagster are good places to start. you can cover the entire bandwidth (from lowest frequency to highest frequency) contiguously with these designs, it doesn't have to be a "multi-band" antenna.