If one antenna operates for Ultra Wideband range (Let 90% BW - 130% BW) with multiple resonances, in that case Is it possible to get a constant gain (With 1 or 1.5 dB variation) over the entire range of frequency ?
Thanking You.
Sounik KIran
Among the various antenna configurations possible, the microstrip fed slot is particularly attractive due to the features like simpler design, low profile planar structure, wider bandwidth, bidirectional/omni-directional radiation patterns and increased degree of freedom for applying impedance matching techniques to get a wider bandwidth. Using a rectangular slot antenna with stepped sections
and fed by an optimally mitred L-shaped microstrip feed terminated by a flared microstrip stub helps in reducing the overall size of the antenna and ensures a better impedance matching over a wider bandwidth. The resonant frequencies for such a configuration can be further altered by loading the microstrip feed
line with open circuit microstrip stub. The stub acts as an open circuit termination
for the microstrip line which increases the capacitance of the structure and can be used to tune the frequency over which the slot resonates. Alternatively, the capacitance of the microstrip line can be increased by increasing the width of the microstrip line. However, changing the width also changes the impedance of the line. To obtain a smoother change in impedance as well as capacitance, the microstrip line is flared from the centre of the slot to obtain the geometry you want.
You can modify the slot and feed line to get the best impedance characteristics.
The impedance bandwidth is from 3 GHz to 27 GHz which is well beyond the UWB range defined by the FCC. In this way, you can obtain a reasonably constant peak gain in the UWB region.
best regards.
The micro strip is popular for narrow band operation. To create wide band, you may have to go for meta material which will provide multiple resonance. However, the flatness in a gain what you are expecting, is difficult task (I would not say impossible), one need to really work on it analytically and experimentally.
Best of luck
No, it is difficult because as frequency increases, directivity of the antenna increases. This thing will make a difference over which you are expecting gain with a variation of 1 or 1.5 dBi.
It is extremely difficult to achieve that is why we prefer horn antennas for constant gain applications for UWB.
Variation is simple patch antenna is approx 1-3 dBi.
Sameer
The basic answer is "Yes, you can."
You can get constant gain (3dB range, i.e. +/- 1.5dBi) from a typical small element UWB antenna across a 3:1 range in frequency. With a bit of work, you can achieve even flatter performance (
Yes, we can.
Metamaterial is one of the options.
Mr. Hans G. is right
gain and BW are two attributes that needs to strike a balance depending on specs and professional requirements - this is the first principle. However, gain and BW enhancing techniques are available such as parasitic loading of patches or radiating elements, or stacking, and even being able to provide wider impedance matching techniques - using curved or stepped transformers particularly when multi octave matching is necessary. metamaterials help, but not so-much that octave bands can be possible. another way is to go for fractals and other progressive geometric structures with suitable matching techniques.
the above is applicable to a single type of polarization only
- Badges
- Science topic