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balanita
Antenna-Theory.com Newbie

Joined: 17 Sep 2009
Posts: 2

 Posted: Thu Sep 17, 2009 9:27 am    Post subject: SLL sidelobe level: for instance, is better to have an SLL of -17dB or -27dB? my professor said that it is better to have an SLL of -17dB and it is a bit confusing... please help!
bigSteve
Antenna Wizard

Joined: 14 Mar 2009
Posts: 265

 Posted: Thu Sep 17, 2009 4:00 pm    Post subject: Side Lobe Level Typically, for a fixed array size (or fixed antenna size), if the sidelobe level is lower, the beamwidth will be higher (less directive). Hence, for very low sidelobes you might end up with a beamwidth larger than you would like. You can't say -17 dB sidelobes is better than -27 dB sidelobes or vice versa. Engineering is all about tradeoffs, and it depends on the particular application.
Mohammed
Antenna Theory Regular

Joined: 10 Nov 2009
Posts: 14
Location: malaysia

 Posted: Tue Nov 10, 2009 5:04 am    Post subject: talking about sidelobe level is a bit confusing and the more l read about it the more confusion i got ... anyhow, what should be my expected sidelobe level for a smart broadband antenna and how will that reflect in my throughput .... your hlep is highly appreciated regards
bigSteve
Antenna Wizard

Joined: 14 Mar 2009
Posts: 265

 Posted: Tue Nov 10, 2009 5:55 am    Post subject: The sidelobe level depends on how many antennas (or elements) are in the array. If there is a single antenna, the sidelobe level depends on how large the antenna is (for instance, a horn antenna that is 5 wavelengths long will have higher sidelobes than a horn that is 10 wavelengths long). There is no way to estimate the sidelobe level for a "smart broadband antenna". Throughput cannot be estimated by just the antenna pattern alone. You need to know what modulation scheme you are using, what bandwidth, what range...etc
SamuraiNeophyte
Antenna-Theory.com Newbie

Joined: 03 Dec 2009
Posts: 1

 Posted: Tue Dec 08, 2009 11:09 pm    Post subject: You can also change sidelobe levels in an array by changing the amplitude levels in the elements, phase, element positions, etc. There are many degrees of freedom to work with and the more elements the more degrees of freedom. Certain amplitudes will give you the most gain for a required SLL.... The desired SLL can be application dependent, location dependant, and gain dependent.
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