论坛上关于PBG/EBG LHM/DNG的文章1

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Hi, everyone!

The last time I chat about PBG topic, people posted really fundamental a
nd simple

questions. Today, it seems very have had experiences and knowledge of PB
G. So,

I feel PBG has been actively studied by many people.

Since most questions have been taken care of, I will join in <jinfoxhe>'
s discussion.

I think when <Why> quoated 光子晶体 as PBG, I think <Why> meant Photonic
Crystal

which should be the appropriate translation. While PBG is 管子带隙 (as y
ou refer to

correctly). The name "Photonic Crystal" was the first to introduced. The
y were very

small in size, only a few microns. Their applications were in the optica
l regime and they

are usually 3-dimensional. Later on, many researchers follow-on the rese
arch and they

were mainly interested in 2-dimensional structure because they are easie
r to make.

Since when we think of "crystal", we think 3-D, so for the newly 2D stru
ctures,

researchers generalise that structure to the more appropriate Photonic B
andgap. These

were discussed in the meeting with all the leading research group to agr
ee on a

conventional name. For those designing 3D structure and for opticl appli
cations are still

refer to Photonic Crystals (PCs).

On the other hand, the microwave engineers have been redesigning the str
uctures

since 1996 such that they are applied in the millimetre-wave and microwa
ve region.

These work were mostly carried out in Europe, mainly by European Space A
gency and

a few institutions in Spain and UK. They have called it the Electromagne
tic Bandgap

(EBG) Structure. Then we had the High-Impedance Surfaces by Sievenpiper  
et. al,

which behaves like a Perfect Magnetic Conducting Surface (理想导磁面) as
described

by <Son_of_wind>. Some researchers now would call it Artificial Impedanc
e Surfaces.

So, as you can see, there are many names. These names are necessary, bec
ause they

are constructed differently. Their idea are similar but they behaviour a
ren't.

But PBG and EBG are moving on now. Have you heard of the new "Negative R
efractive

Material", or "Left-handed Material" or "Double Negative Material"? Thes
e materials has

either -ve permittivity or -ve permeability or both -ve. Allowing a plan
e-wave to enter

from one side and exit on the side in a converged manner, therefore ante
annas can

be made more directive. While in Astronomy, we can achieve the so-called


"Perfect Lens". These materials, plus the materials discussed above (PBG
, EBG etc...)

are set to become the "Metamaterial". This will be the general name for  
all of the

above materials.

In my mind, I always consider them as just periodic structures. However,
my interest is

with the EBG, high-impedance surfaces and negative refractive material.

I hope the above comment answered your question and sorry to write so mu
ch.