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what kinds of antennas are UWB antennas ? - RF Cafe Forums
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snowpea
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Post subject: what kinds of antennas are UWB antennas ?
Posted: Fri Sep 23, 2005 10:33 pm
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hi all how to define a uwb antenna? and how
many antennas can be seen uwb antennas ?
Thank you all snowpea
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UWB_antenna_guy |
Post subject: Re: what kinds of antennas are UWB antennas ?
Posted: Mon Sep 26, 2005 9:29 am
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
snowpea wrote:
hi all how to define a uwb antenna? and
how many antennas can be seen uwb antennas ?
Thank you all snowpea
by definition a UWB antenna has at least
a 500MHz bandwidth or a fractional BW of 25%.
UWB antennas are usually non-resonant and come
in many different flavors, e.g., magnetic/electric
antenna, omnidirectional, directional, etc.
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Graham |
Post subject:
Posted: Tue Sep 27, 2005 6:47 pm
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Colonel |
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Joined: Fri Sep 02, 2005
7:25 pm Posts: 34 Location: Hampshire UK
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Discone is one style designed to be very wide band.
Another is log periodic, famously wideband. Helical
antennas can also be usefully wide. Making
the dipole elements in a Yagi of wide flat strip
has a broadening effect. I have always wondered
how a common UHF yagi as used for TV reception can
be so wide as to be good for such a large range
of channels. I never actually tested one (maybe
I should - but any I ever handled had to be installed
damn quick before the game started, or whatever
other urgency). They look like they should be
resonant at some favoured frequency, but what they
actually do is not well described amid the hype
about picture quality etc.
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snowpea |
Post subject:
Posted: Thu Sep 29, 2005 10:03 pm
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Graham wrote:
Discone is one style designed to be very wide
band. Another is log periodic, famously wideband.
Helical antennas can also be usefully wide.
Making the dipole elements in a Yagi of
wide flat strip has a broadening effect.
I have always wondered how a common UHF
yagi as used for TV reception can be so wide
as to be good for such a large range of channels.
I never actually tested one (maybe I should
- but any I ever handled had to be installed
damn quick before the game started, or whatever
other urgency). They look like they should
be resonant at some favoured frequency, but
what they actually do is not well described
amid the hype about picture quality etc.
dear Graham: i read some books and find
nearly all the antenna you said belong to the conventional
antennas , while the moden uwb antenna are has some
new characters such as Mr uwb antenna boy' said
. i have more interest in the new uwb antennas
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UWB_antenna_guy |
Post subject:
Posted: Mon Oct 03, 2005 8:47 pm
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
snowpea wrote:
Graham wrote:
Discone is one style designed to be very
wide band. Another is log periodic, famously
wideband. Helical antennas can also be
usefully wide. Making the dipole
elements in a Yagi of wide flat strip has
a broadening effect. I have always
wondered how a common UHF yagi as used for
TV reception can be so wide as to be good
for such a large range of channels. I never
actually tested one (maybe I should - but
any I ever handled had to be installed damn
quick before the game started, or whatever
other urgency). They look like they should
be resonant at some favoured frequency,
but what they actually do is not well described
amid the hype about picture quality etc.
dear Graham: i read some books and
find nearly all the antenna you said belong
to the conventional antennas , while the moden
uwb antenna are has some new characters such
as Mr uwb antenna boy' said . i have more interest
in the new uwb antennas
there are tons of papers in the IEEE transaction
of antennas and propagation. I'd also suggest checking
out the conference proceedings for the annual IEEE
symposium on APS.
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snowpea |
Post subject:
Posted: Wed Oct 05, 2005 10:39 pm
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dear UWB boy : can i ask you some more questions
: except the band width of uwb antenna : 25%
+ or 500MHz + is there more demands for uwb antenna
? for instance , the sizes ? and how about if
we use microstrip antenna to have a uwb antenna
research ? Thanks
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UWB_antenna_guy |
Post subject:
Posted: Thu Oct 06, 2005 9:59 am
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
snowpea wrote:
dear UWB boy : can i ask you some more questions
: except the band width of uwb antenna :
25% + or 500MHz + is there more demands for
uwb antenna ? for instance , the sizes ?
and how about if we use microstrip antenna to
have a uwb antenna research ? Thanks
not quite a boy any more
well, the definition states that the fractional
BW of an UWB antenna shall be at least 25% and that
the absolute BW shall be at least 500MHz.
there are quite a few companies working on UWB
products, e.g., Staccato Communications, Alereon,
Wisair, Intel, Pulse Link, Freescale, T-Zero. Not
all of above companies work actively on antennas,
most of them turn to antenna companies to develop
UWB antennas for them. In most cases, they are interested
in size and care less about performance (as far
as I have seen). In the press, you mostly see LTCC
module antennas mounted over ground planes. I am
not the biggest fan of those but people with little
insight into antennas are fascinated by them...
UWB antennas are very often fed by microstrips.
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gnomus |
Post subject:
Posted: Thu Oct 06, 2005 11:48 am
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Antennas like a log periodic and discone have ,
what has been called, ultra-wideband charcteristics,
but they are used to receive
narrow bandwidth
signals!. Their resonant point along their
structure over frequency results in a true UWB signal
being distorted because the phase relationship over
frequency changes. The UWB antennas of today
are intended to receive UWB signals and should have
little phase delay change over frequency so the
UWB signal does not get phase distorted.
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Graham |
Post subject:
Posted: Tue Oct 11, 2005 7:46 am
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Colonel |
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Joined: Fri Sep 02, 2005
7:25 pm Posts: 34 Location: Hampshire UK
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Hmm.. this thread could go far.. OK - a log-periodic
is actually a whole series of antennas in a structure
that also performs that function of a combiner.
But I think all parts of the structure do contribute.
There would probably be "time of arrival" issues
when receiving spread spectrum or widely modulated
stuff, where phase delays between parts of the structure
mess things up. Its usefullness is actually in the
fact the one high gain antenna can transmit and
receive narrowband signals anywhere in a wide band.
Anyways, my mind is already generating alternative
structures to get around this while preserving the
gain. If I can think it, then loads of those cleverer
fellows who write the IEEE transaction papers that
UWB_antenna_guy mentioned will also think it. Lets
not get hung up on log-periodic. It does what it
does real well, and this may not suit a signal with
components that sprawl actoss the band. Explore
the fractal antennas if you want the avant-garde
wideband.
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UWB_antenna_guy |
Post subject:
Posted: Tue Oct 11, 2005 8:55 am
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
I did some work on log-periodics. They are in the
class of so-called frequency independent antennas.
That means, that they are mainly defined by angles
and that the radiation of a certain frequency occurs
from an active region. This region moves along the
antenna with frequency which therefore causes the
phase distortion. These antennas have good use in
GPR and radar applications where antennas are used
at stepped frequencies (basically repeating what
others have said previously). Graham, why
would you think that fractal antennas will be big
in UWB. In my opinion, they are overrated. There
was a huge hype about them years ago and hardly
any outcome...
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Guest |
Post subject:
Posted: Wed Oct 12, 2005 9:21 am
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UWB_antenna_guy wrote:
I did some work on log-periodics. They are in
the class of so-called frequency independent
antennas. That means, that they are mainly defined
by angles and that the radiation of a certain
frequency occurs from an active region. This
region moves along the antenna with frequency
which therefore causes the phase distortion.
These antennas have good use in GPR and radar
applications where antennas are used at stepped
frequencies (basically repeating what others
have said previously). Graham, why would
you think that fractal antennas will be big
in UWB. In my opinion, they are overrated. There
was a huge hype about them years ago and hardly
any outcome...
Dear uwb antenna guy : as you mensioned
the phase distortion of an antenna , then , can
i use software ,for example , HFSS or IE3D , to
simelate an atnenna's phase distortion ? and what
step should i take ? best regards
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UWB_antenna_guy |
Post subject:
Posted: Wed Oct 12, 2005 10:46 am
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
Anonymous wrote:
Dear uwb antenna guy : as you mensioned
the phase distortion of an antenna , then ,
can i use software ,for example , HFSS or IE3D
, to simelate an atnenna's phase distortion
? and what step should i take ? best regards
I don't know IE3D but it should be similar.
In HFSS, you need to setup a far-field analysis
and HFSS will give you a lot of far-field parameters
as output variables. I'd pick a radiated electric
field and plot the phase of that field that gives
you a clue about the phase linearity of the antenna...
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jian@zeland.com |
Post subject: Phase Distortion
Posted: Wed Oct 12, 2005 12:18 pm
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Hi, Guest: In IE3D's patternview, it allows you
to find the 2-port s-parameters and/or transfer
functions between Tx and Rx antennas. From the 2-port
s-parameters of transfer functions, you can investigate
the phase distortion. If you want to check time
domain, you can use MDSPICE to perform a time transient
analysis.
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Woshifanka' |
Post subject: Re: Phase Distortion
Posted: Thu Oct 13, 2005 9:53 am
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jian@zeland.com wrote:
Hi, Guest: In IE3D's patternview, it allows
you to find the 2-port s-parameters and/or transfer
functions between Tx and Rx antennas. From the
2-port s-parameters of transfer functions, you
can investigate the phase distortion. If you
want to check time domain, you can use MDSPICE
to perform a time transient analysis.
Dear Sir Jian: Nice to meet you here.
According to your words , i take the uwb antenna
model:oval_dipole.geo as an example, which is
introduced in the ie3d manual in chapter 11, section
7. yes , i can use PatterView to get the transfer
functions , also get the "TX_RX_0.SP", which contain
the s-paremeters of Tx and Rx antennas . now
, i have my question : is the the phase about the
antenna's voltage's phase , or about other parameters'
, i want to know clearly the full defination of
the 'phase' . then, how to deal with the "TX_RX_0.SP",
to get the phase ? Thanks in advance . kaka
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jian@zeland.com |
Post subject:
Posted: Thu Oct 13, 2005 11:29 am
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Hi, Fanka: The resulting 2-port s-parameters between
the Tx and Rx antennas contains all the information.
They govern the relationship between the incident
field and reflected field between the Tx and Rx
antenna. Certaily, you can convert it to Z or Y-parameters
(on MODUA) for the relationship between V and I.
Basicallly, they contain all the information between
the linear network (considering the Tx and Rx antennas
as one single system). You can find the phase differences
between the input and output under ANY excitaiton
and termination conditions as long as they are linear.
If they are not linear, you can use SPICE to find
the time transient. In fact, MDSPICE can do jobs.
Regards.
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Graham |
Post subject:
Posted: Thu Oct 13, 2005 7:55 pm
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Colonel |
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Joined: Fri Sep 02, 2005
7:25 pm Posts: 34 Location: Hampshire UK
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Hi Guys Firstly, reading some of the postings,
I feel I might rapidly get out of my depth here.
My antenna experience was in exploring all kinds
of quadrifilar helix using NEC2. That is, I find
the radiation pattern and the feedpoint impedances.
Time domain simulation is not where I have been,
and I have not met IE3D or HFSS. For UWB_antenna_guy
Quote:
Graham, why would you think that fractal antennas
will be big in UWB. In my opinion, they are
overrated. There was a huge hype about them
years ago and hardly any outcome...
At the time, I thought it was all hype also,
but it seems they are still around, and may have
developed to actual product. I don't know if any
have made it to patent. Try a search using "fractal
antenna" and we find Fractal Antenna Systems Inc
has a load of new wideband product. (BTW - I have
no commercial interest in this company).
Also, I see it asserted here
https://www.hbci.com/~wenonah/cfa/fractal.htm
that a log-periodic
is actually fractal in nature, but supposedly misunderstood
until fractal techniques were applied. The main
proponent is a Dr. Nathan Cohen. I begin to wonder
if he is also the fellow known as "Chip" who posted
into antenna groups some years back about fractal
antennas.
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UWB_antenna_guy |
Post subject:
Posted: Thu Oct 13, 2005 9:08 pm
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
@Graham I have not followed patents too much
since I don't see much value in an antenna patent.
Based on my observations at antenna conferences,
fractal antennas still don't play a major role in
UWB antennas. I have seen two or three antenna companies
specializing in fractal antenna designs but only
one has announced a UWB antenna. I am still waiting
to see a spec sheet on it though...
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UWB_antenna_guy |
Post subject: Re: Phase Distortion
Posted: Thu Oct 13, 2005 9:17 pm
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
Woshifanka' wrote:
Dear Sir Jian: Nice to meet you here.
According to your words , i take the uwb
antenna model:oval_dipole.geo as an example,
which is introduced in the ie3d manual in chapter
11, section 7. yes , i can use PatterView
to get the transfer functions , also get the
"TX_RX_0.SP", which contain the s-paremeters
of Tx and Rx antennas . now , i have my question
: is the the phase about the antenna's voltage's
phase , or about other parameters' , i want
to know clearly the full defination of the 'phase'
. then, how to deal with the "TX_RX_0.SP",
to get the phase ? Thanks in advance .
kaka
As I mentioned earlier, I don't know IE3D.
I am familiar with FDTD and HFSS only...
I have a comment about previous statements.
It sounded like that IE3D calculates transfer functions.
Based on my experience with transfer functions,
it describes the behavior of a system, that is,
two antennas and the separation between them.
In order to determine an antenna's phase
distortion, I am interested solely in the far-field
characteristic of a single antenna (aka the antenna
under test). A transfer function on the other hand
includes the phase response of both antennas. You
cannot determine the phase response of the AUT unless
you know the phase response of one antenna (in the
system) or both antennas are identical.
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Woshifanka' |
Post subject:
Posted: Thu Oct 13, 2005 9:58 pm
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hi UWB_antenna _guy : forgive my poor English
understanging. as it is not my mother language .
as you menstioned : " You cannot determine the phase
response of the AUT unless you know the phase response
of one antenna (in the system) or both antennas
are identical. " Can you explain the "AUT" ?
I don't what dose it mean. Thanks very much
kaka
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Woshifanka' |
Post subject:
Posted: Thu Oct 13, 2005 10:54 pm
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jian@zeland.com wrote:
Hi, Fanka: The resulting 2-port s-parameters
between the Tx and Rx antennas contains all
the information. They govern the relationship
between the incident field and reflected field
between the Tx and Rx antenna. Certaily, you
can convert it to Z or Y-parameters (on MODUA)
for the relationship between V and I. Basicallly,
they contain all the information between the
linear network (considering the Tx and Rx antennas
as one single system). You can find the phase
differences between the input and output under
ANY excitaiton and termination conditions as
long as they are linear. If they are not linear,
you can use SPICE to find the time transient.
In fact, MDSPICE can do jobs. Regards.
hi , Jian: thanks for your guides .
now i have a more clear understanding of the
phase problem . but for IE3D , i wish i can get
the figure which the X-axis is frequency , and the
Y-axis is the phase . Also i take the "oval_dipole.geo"
as an example . I try to use MODUA -->control-->Define
Disply Graph--->Magnitude and Phase of S-Parameters
to plot the Ang(1,1) and Ang(2,1). but the curve
is not linear in the band . I am afraid that
i made a mistake , since for the uwb TX-RX antenna
, should have a linear phase . but how can i
plot the right figure about phase vs. frequency
.? correct me if i am wrong . thanks very
much. kaka
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UWB_antenna_guy |
Post subject:
Posted: Fri Oct 14, 2005 12:31 am
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Colonel |
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Joined: Tue Aug 09, 2005
1:07 pm Posts: 28 |
Woshifanka' wrote:
hi UWB_antenna _guy : forgive my poor English
understanging. as it is not my mother language
. as you menstioned : " You cannot determine
the phase response of the AUT unless you know
the phase response of one antenna (in the system)
or both antennas are identical. " Can you
explain the "AUT" ? I don't what dose it mean.
Thanks very much kaka
sorry, AUT means Antenna under test. Take
a gain measurement with just two antennas. You can
determine the gain of the antenna under test (AUT)
if you have a network analyzer and know the gain
of the reference antenna (the other antenna) or
if both antennas are identical.
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Guest |
Post subject:
Posted: Wed Nov 09, 2005 2:53 am
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UWB_antenna_guy wrote:
I did some work on log-periodics. They are in
the class of so-called frequency independent
antennas. That means, that they are mainly defined
by angles and that the radiation of a certain
frequency occurs from an active region. This
region moves along the antenna with frequency
which therefore causes the phase distortion.
These antennas have good use in GPR and radar
applications where antennas are used at stepped
frequencies (basically repeating what others
have said previously). Graham, why would
you think that fractal antennas will be big
in UWB. In my opinion, they are overrated. There
was a huge hype about them years ago and hardly
any outcome...
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woshifanka |
Post subject: Re: Phase Distortion
Posted: Sat Nov 19, 2005 4:06 am
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Joined: Tue Aug 09, 2005
2:33 am Posts: 2 |
UWB_antenna_guy wrote:
Woshifanka' wrote:
As I mentioned earlier, I don't
know IE3D. I am familiar with FDTD and HFSS
only... I have a comment about previous
statements. It sounded like that IE3D calculates
transfer functions. Based on my experience
with transfer functions, it describes the
behavior of a system, that is, two antennas
and the separation between them.
In order to determine an antenna's phase
distortion, I am interested solely in the
far-field characteristic of a single antenna
(aka the antenna under test). A transfer
function on the other hand includes the
phase response of both antennas. You cannot
determine the phase response of the AUT
unless you know the phase response of one
antenna (in the system) or both antennas
are identical.
Dear UWB_antenna_guy: In general, we
make a single antenna model in HFSS firstly , and
run HFSS to get the antenna's parameters . Then
how to set in HFSS can i get the phase response?
i read your words and try it but not get the way.
since the transfer function shoude include two antennas
, i think . so , please tell me your steps in HFSS
and i will appreciate you very much. best regards.
kaka
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tomw3 |
Post subject: New UWB antennas
Posted: Fri Dec 16, 2005 1:31 pm
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Hi snowpea, If you are still interested in
new UWB antennas please check out the article entitled
"Monopole with a Twist Revisited" in the Microwave
Journal for July 2005. It describes a fairly compact
UWB antenna capable of good VSWR over several octaves.
Since the article was published we've significanly
reduced the antenna volume while still maintaining
the VSWR bandwidth. No UWB antenna meets
every need, but this one seems handy for mobile
communication. javascript:emoticon(':)')
Smile
snowpea wrote:
Graham wrote:
Discone is one style designed to be very
wide band. Another is log periodic, famously
wideband. Helical antennas can also be
usefully wide. Making the dipole
elements in a Yagi of wide flat strip has
a broadening effect. I have always
wondered how a common UHF yagi as used for
TV reception can be so wide as to be good
for such a large range of channels. I never
actually tested one (maybe I should - but
any I ever handled had to be installed damn
quick before the game started, or whatever
other urgency). They look like they should
be resonant at some favoured frequency,
but what they actually do is not well described
amid the hype about picture quality etc.
dear Graham: i read some books and
find nearly all the antenna you said belong
to the conventional antennas , while the moden
uwb antenna are has some new characters such
as Mr uwb antenna boy' said . i have more interest
in the new uwb antennas
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Posted 11/12/2012
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