CPW feed for microstrip antenna

[icpinu]

Hi,

Can you have a CPW feed for any microstrip antenna? For example, could you have a CPW fed circular patch antenna? Or do you need to have a Finite Ground-CPW antenna.

Many thanks

 

[ferdows]

hi
yes its common models of antenna
which kind of antenna u want?

 

[icpinu]

I am looking for a high gain antenna. Besides a normal dipole or Quasi yagi which antenna would you design?
Thanks

 

[ferdows]

hi
yagi have gain between 8-10 but very uwb usually CPW use for uwb application u can use some technique for increase gain
at which frequency u want antenna?

 

[icpinu]

I am trying to work at 60 GHz

 

[ferdows]

hi
see this paper
Compact 60-GHz Tapered Slot Antenna Printed on LCP Substrate for WPAN Applications
which kind of antenna u want at this frequency?

 

[icpinu]

Hi thanks for the paper. I am very new in antenna design. But I am looking for an antenna with the highest gain possible maybe an array. I am not very concerned about bandwidth.

 

[ferdows]

hi
do u have limitation about antenna pattern or not ? CPW antenna had semi omni pattern but other like slot Vivaldi is directive

 

[icpinu]

Hi thanks for rEplying. I don't have limitations about the pattern. But as directive as possible would be ideal.

Many thanks

 

[ferdows]

hi
yagi and quasi yagi are common model for 60GHz application ant the yagi gain much than other kind so for more high gain it can combine with TEM horn like a paper of ITOH or it can use with cavity back or ABS

 

[mamali]

Hi,
As for the first question, NO, you can not feed microstrip antennas with CPW, BUT, keeping in mind that CPW is actually more like a two-line feed (the wave is going in the slots), you have similar antennas as microstrips, just a little different. For example, a microstrip dipole is, of course, just a long narrow patch of metal, connected to a microstrip feed; a CPW dipole is something like the opposite, two long narrow slot in the ground plane, left one connected to the left CPW slot, right one connected to the right slot of CPW.
As for your second question, if you don't need a wideband antenna, I don't know why everybody talk about UWB solutions, maybe its just because of the frequency which is a UWB one. If you do not need a wideband solution, and you only need very high directivity, the obvious solution is an array, the easiest one a uniform array of serial dipole slots, but a parasitic coupled array with a match load at the end is more uniform, you can find it in microstrip antenna handbooks, say, Gupta. However, you should keep in mind that slot antennas (fed by CPW or not) are radiating in both planes, more like omni directional antennas. If you want it only in one plane, you will need a second ground plane at the back, which can usually be realized using a two-side copper clad substrate.
And you have to also keep in mind that realization of CPW in 60GHz is not such an easy job itself. The line width / gap ratio should be small to realize 50 ohm matching, and the gap goes into micron range. However, CPW feed is a very good feed for this frequency regarding loss. A considerable portion of the wave travels in the air, reducing the dielectric loss that is high in these frequencies.
If you have more specific questions, please feel free to ask, please provide enough info of the design requirement in that case.
yours,
Marti

 

[ferdows]

hi
i dont know why some one with out enough knowledge interfered in every thing for more information about CPW feed see this paper in IEEE :

A 60-GHz Millimeter-Wave CPW-Fed Yagi Antenna Fabricated by Using 0.18- \mu\hbox {m} CMOS Technology

and pls didn't give wrong information to others

 

[mamali]

hi
i dont know why some one with out enough knowledge interfered in every thing...
and pls didn't give wrong information to others

Who do you mean? And which wrong information? Please kindly express.

 

[icpinu]

Hi , thank you so much for all the help. I will start right away with the design. To Ferdows can you explain what is wrong with the explanation of Marti? Since I am a newby in this field I don't have enough knowledge to see what is wrong fm the replies until I test it with simulations.

Another question What is the best book for designing antennas , specially planar antennas. I have to start simulations and don't have a lot of time to learn all the basics so any book that decribes antennas and design methodology in a concise way would be perfect. And just to confirm I am moving in the right direction. Is quartz the best substrate for this frequencies?

Many thanks

 

[ferdows]

hi icpinu
first: every one know that the Maxwell equation is base of antenna design and simulation and its not alter in material or frequency and solution method that u chosen. so that awfully some one said cpw impossible in one frequency .
second:for increase gain every one can said array method but its not merit of designer when a person design an antenna element with high gain its a merit.
third : UWB usually needs in every new system and every one knows the benefits of UWB antenna and system
at last i should add that design antenna at 60 GHz frequency not hard but fabrication is hard if u dont have enough support and u can use many material at that frequency like material with silicon structure or ceramics and polymers

 

[icpinu]

Hi Ferdows,

Thanks again for the very useful reply and all the help provided.
This has saved me a lot of time.

All the best

 

[ferdows]

hi icpinu
i hope my help useful for u and other if u have problem more u can email to me

 

[icpinu]

Will do that, thanks

 

[nf707]

in slot antenna that fed bu CPW because the wave is going in the slots, hence the Q(quality factor) is decreased and these antennas have wider bandwidth compare to patch antenna. the main drawbak of these antenna is that those radiation is bidirectional.

 

[mamali]

hi icpinu
first: every one know that the Maxwell equation is base of antenna design and simulation and its not alter in material or frequency and solution method that u chosen. so that awfully some one said cpw impossible in one frequency .
second:for increase gain every one can said array method but its not merit of designer when a person design an antenna element with high gain its a merit.
third : UWB usually needs in every new system and every one knows the benefits of UWB antenna and system
at last i should add that design antenna at 60 GHz frequency not hard but fabrication is hard if u dont have enough support and u can use many material at that frequency like material with silicon structure or ceramics and polymers

First: "that awfully some one said cpw impossible in one frequency!" I'm not saying it's impossible, but it's hard because of the dimensions; when you have such a high frequency design, the dimensions become very small. As an example: on Rogers RT/duroid 5880 substrate with thickness .5mm; a CPW with width W = 2mm, and separation S = 50um gives you ~50 Ohms. (or W = 1mm, S = 30 um). Thats it, directly related to maxwell, though!

[BTW, the solution absolutely relates to the material and frequency. Do you seriously think that all maxwellian waves behave the same, no matter of the frequency and the material?! So, there is no difference between 50Hz, 10GHz, infrared, visible light, or Xrays?! Are you jocking? ]

second and third: no comments!

at last: well, silicon is very lossy even for low frequencies, and high resistivity Silicon is very expensive, do not try it at all as a substrate. Most of the standard microwave materials are very lossy in 60 GHz; as an example, the very low loss Duroid 5880 with tand=9x10^-4: a CPW on this material has 45dB/m loss in 10 GHz but 222dB/m in 60 GHz, ironically most of it from the dielectric loss, and it doesn't count for nonlinear behavior after 30GHz. Actually, Rogers only suggest these substrates for under 30GHz designs. The other solution is to use pure ceramic wafers, such as quartz or alumina (they are hard to solder, making vias, ... though). So, just have in mind that making millimeter wave designs is not as easy as it appears.