Anyone having material related to spiral antenna?
Does anyone of you have some material related to the history, characteristics and working of spiral antenna? Any basic info would be useful. So, if you have some, please do share.
Thank you.
This material is related to helical antenna not spiral.
Hi,
may be this will be use full.
Hello,
Do a search on "cavity backed spiral" and you will get useful info on wide band spiral antennas.
I have the book of casewell but this doesn't explain the basic quick facts about spiral.
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Do you know any quick facts about spiral? Also, am I finding difficult to find the material on spiral or this is happening with you as well. I believe I am pretty good at Googling :)
Hello,
I don't have quick facts, but for large bandwidth you need a flared structure, like the logarithmic spiral (log spiral). The Archimedian spiral is also used.
Try Antenna Engineering handbook (Johnson, Jasik). It has more on the spiral then Kraus. Note that spiral antennas are not small with respect to wavelength
But i have seen IEEE papers on spiral with dimension of around 85 mm and freq of 2.45 GHz.
Hello,
You can have small spiral antennas, but the relative bandwidth (BW/CenterFreq) will not be large anymore, or you have to sacrifice radiation efficiency, gain.
Most realy wide band antennas have their lowest usable frequency dictated by half wave or quarter wave electrical length. At their highest frequency, their size is many wave length. Wideband spiral antennas are related to traveling wave antennas.
I suppose there is a relation with your posting on bandwidth ratio?
The lowest freq is 1.2 GHz and the highest freq is around 20 GHz but the gain is just 4-5 dB. Yes, it is related to the bandwidth ratio