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what kinds of antennas are UWB antennas ? - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: what kinds of antennas are UWB antennas ?
Posted: Fri Sep 23, 2005 10:33 pm 
hi all
how to define a uwb antenna?
and how many antennas can be seen uwb antennas ?

Thank you all
snowpea


 
  
 
 Post subject: Re: what kinds of antennas are UWB antennas ?
Posted: Mon Sep 26, 2005 9:29 am 
 
Colonel
User avatar

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.


 
   
 
 Post subject:
Posted: Tue Sep 27, 2005 6:47 pm 
 
Colonel
User avatar

Joined: Fri Sep 02, 2005 7:25 pm
Posts: 34
Location: Hampshire UK
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.


 
   
 
 Post subject:
Posted: Thu Sep 29, 2005 10:03 pm 
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 :)


 
  
 
 Post subject:
Posted: Mon Oct 03, 2005 8:47 pm 
 
Colonel
User avatar

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.


 
   
 
 Post subject:
Posted: Wed Oct 05, 2005 10:39 pm 
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


 
  
 
 Post subject:
Posted: Thu Oct 06, 2005 9:59 am 
 
Colonel
User avatar

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 :wink:

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.


 
   
 
 Post subject:
Posted: Thu Oct 06, 2005 11:48 am 
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.


 
  
 
 Post subject:
Posted: Tue Oct 11, 2005 7:46 am 
 
Colonel
User avatar

Joined: Fri Sep 02, 2005 7:25 pm
Posts: 34
Location: Hampshire UK
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.


 
   
 
 Post subject:
Posted: Tue Oct 11, 2005 8:55 am 
 
Colonel
User avatar

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...


 
   
 
 Post subject:
Posted: Wed Oct 12, 2005 9:21 am 
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


 
  
 
 Post subject:
Posted: Wed Oct 12, 2005 10:46 am 
 
Colonel
User avatar

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...


 
   
 
 Post subject: Phase Distortion
Posted: Wed Oct 12, 2005 12:18 pm 
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.


 
  
 
 Post subject: Re: Phase Distortion
Posted: Thu Oct 13, 2005 9:53 am 
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


 
  
 
 Post subject:
Posted: Thu Oct 13, 2005 11:29 am 
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.


 
  
 
 Post subject:
Posted: Thu Oct 13, 2005 7:55 pm 
 
Colonel
User avatar

Joined: Fri Sep 02, 2005 7:25 pm
Posts: 34
Location: Hampshire UK
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 http://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.


 
   
 
 Post subject:
Posted: Thu Oct 13, 2005 9:08 pm 
 
Colonel
User avatar

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...


 
   
 
 Post subject: Re: Phase Distortion
Posted: Thu Oct 13, 2005 9:17 pm 
 
Colonel
User avatar

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.


 
   
 
 Post subject:
Posted: Thu Oct 13, 2005 9:58 pm 
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


 
  
 
 Post subject:
Posted: Thu Oct 13, 2005 10:54 pm 
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


 
  
 
 Post subject:
Posted: Fri Oct 14, 2005 12:31 am 
 
Colonel
User avatar

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.


 
   
 
 Post subject:
Posted: Wed Nov 09, 2005 2:53 am 
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...


 
  
 
 Post subject: Re: Phase Distortion
Posted: Sat Nov 19, 2005 4:06 am 
 
Lieutenant

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


 
   
 
 Post subject: New UWB antennas
Posted: Fri Dec 16, 2005 1:31 pm 
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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