fractal met a material mono pole antenna what we did

8/6/2019 Fractal Met a Material Mono Pole Antenna What We Did

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FRACTAL METAMATERIAL MONOPOLE ANTENNA: The Metacloak Monopole

Fractal Antenna Systems,Inc. 2009 5 October 2009 (rev 6 Oct)

INTRODUCTION

A White Paper on the Metacloak Monopole will be out on 25 October. In the meantime, lots of folks

want to ask what did you do? This summary addresses that. Keep in mind we have many other antenna

and array examples and types (with more expanded radiation characteristics), and we present this one

as the simplest and easiest to learn from. There will be a peer reviewed journal publication that explains

the results and why they are importantscientifically. Right now the best practicaltakeaway is that

this new technology allows you to define a new CLASS of antenna design where antennas are made

from layers of fractal metamaterial circuit boards, that cover without connections and have unusual

properties of bandwidth and control of power pattern. Hence, in this case, a slip-on. Think: walls;

vehicular and vessel sides; clothes; coverings; surfaces in general. Also, we do have patents on this

technology with others pending; weve been doing this for quite a while.

Additionally, we wanted everyone to have a sense of the ahah! moment, so theres no super-slick

super-fabbed antenna held by a squeaky clean grad student in a white labcoat. There is no machine

that goes ping. Certainly we make ISO rated antennas and sell them, and they do look and are slick. This

is the story of the LAB PROTOTYPE. This is how things really get DISCOVERED. If you are an antenna guru

who is offended by an allusion of an antenna looking like a marshmallow, well, we humbly apologize.

We had fun with it and thats what learning should be.

Finally, we will be showing oodles of data in the journal article. The cloverleaf lobes issue refers to the

ELEVATION plots and we havent shown those yet. The point is that a monopole grows cloverleaf

lobesin elevationwhen its length exceeds about 2/3 of a wave. You dont see that here in the slip-

on (metacloak) monopole, and it tells you something interesting.

We understand plasmonics well and that is the fundamental physics in play here. More in the journal

paper: most people go glassy eyed when you talk about plasmonics. And, for informational purposes,

we have not found transformational optics useful in guiding our approaches. We do not use it. Your

approach to metamaterials may differ.

WHAT DID YOU DO?

We took a wave monopole antenna and then placed a specially designed slip-on cloak made of fractal

metamaterials. This cloak or layered collar is made of thin circuit boards around and in an airfoam

cylinder; a small copper fluted base; and blue RF transparent tape. The metacloak literally slips on over


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the wire of the monopole. There is NO DIRECT CONNECTION. There are NO PARTS. There is NO

AMPLIFIER. There is no TRANSFORMER. There is NO BATTERY. Its just a piece that looks like a long

marshmallow covered with a doily copper pattern and blue tape. It could have been shot out from a

Nerf gun, for all appearances.

Here it is below:

Heres a picture of the parts that went into it (in various stages of completion):


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We then measured the power pattern and the SWR of the antenna before and after the slip-on. The

differences were dramatic:

PASSBAND tripled in bandwidth and was CONTINUOUS POWER PATTERN remained OMNI with NO CLOVERLEAF LOBES (in elevation)at the higher

frequencies

GAIN increased monotonically with frequency and was at least 4 dB higher at the high end thanexpected from mismatch correction alone

SECOND HARMONIC of the cloaked monopole was no longer resonant and no longer radiatedwell

Thus the effect of the metacloak were more than a mere impedance matching device. To wit: the

entire radiating properties of the structure changed and NO LONGER were those of the parent

monopole.

Clearly the metacloak has become its own antenna, and is parasitically excited by the monopole. The

current on the metacloak must be in- phase and continuous, with tapering at the end, for the power

pattern and gain conditions to be explained, a totally unexpected result for a monopole. Needless to

say, making a wideband monopole without components or matching is also, to be polite, unusual.

This thus defines a new and unique approach to antennas where their characteristics may be defined by

layers of fractal resonators functioning as a metamaterial composite, thus removing needs for

components; a matching system; multiple elements; and so on. The performance characteristics are

both unique and simple to attain in a practical way.

Below is a nice diagram summarizing the data and results:


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fractal met a material mono pole antenna what we did

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