Ultra Wideband Antenna for 400 Mhz-800 Mhz frequency range

Hello, I searched for Ultra Wideband Antenna Design, but I found it very hard to find the design for this (400-800 Mhz) frequency range, so I ask to anyone who know about this antenna, and I only know hfss, 4nec2 and MM-Managal software

1. If I use broader range e:g 400-1000 MHZ, will it be any effect that harm the performance?
2. This antenna for electromagnetic harvesting, so whoever know which one will be more effective, wide-band or narrow-band?
3. Is it possible to make Ultra Wide Band antenna that have gain higher than 7 dB and size smaller than 50x32 cm ?

Thanks..

try conical skirt or discone, they have wideband characteristics.

Hello,

I think you will not be able to make a 400..800 MHz antenna with minimum gain of 7 dBi (over the full frequency range), given your size limitations. It will be hard to get an aperture efficiency of over 100%. What is the third dimension? If it must be an omnidirectional antenna, it will have large size, as you need to combine the outputs from several vertically stacked elements.

Regarding wide band or narrow band: If your interesting frequencies are spread across the band (or you don't know them in advance), you need the wide band antenna, or seperate narrow band antennas.

The narrow band approach may be attractive seen from the AC to DC converter. At low power you need careful matching between antenna an rectifier. Depending on what rectifier (schottky diode) you will use, broadband matching together with highest efficiency may not be possible.