shorted patch antenna help

[simazafrani]

Hi...
i'm doing project about shorted patch by using CST. what i did was, i design square patch antenna and i make a hole at one part of the patch, which i put a pin with radius of 0.5mm (connected patch to ground). i got a good result in simulation (dual frequency RL <-10dB) , but the efficiency was quite low..which is around 35%. i haven't fabricate the antenna yet, becoz i'm still not sure about this.
what make me wonder is...was i did the right thing to design shorted patch antenna? or i misunderstood the meaning of shorted patch....

Hope someone here can help me in order to understand this...
Big Thanks...

 

[ferdows]

hi
u antenna efficiency is lower than normal i think u antenna bandwidth is lower than normal because efficiency related to S11 and when u s11 less than 15 it became good so u should change u antenna matching and restructure u antenna

 

[simazafrani]

Hi..tq for the reply...
FYI...my antenna resonates at 3 different freq at 1.126 GHz (-24.4dB, BW 40MHz), 2.45 GHz (-20.96dB, BW 73 MHz) and at 2.9 GHz (-21dB, BW 91 MHz). I think this result is good enough, but due to its low efficiency..i'm afraid i would not get a good measurement result of the fabricated antenna. Can u give any suggestion for me to improve its efficiency?
Thanks again...

Here i attached the design n S11

 

[ferdows]

hi
1- i saw u file and u result look true but i think u have wrong in u simulation and i attach a file for more information
2-CST had some problem with resonance antenna like microstrip so i advise u to check u result with HFSS
3- i thick u port definition have fault i want to know how was it
4- i want to know whats u antenna substrate may be can change efficiency by change material

 

[simazafrani]

Hi Ferdows....
1. thanks for the attachment
2. Currently, i only have CST software...thats the only choice i have...didn't have HFSS and never have experience with it
3. hmm...port definition? i'm using microstrip line feed which i define port at the end of the line( cover Ground thickness, Substrate thickness and microstrip line thickness)
4. i'm using FR4, Er = 4.7 and thickness 1.6mm

Thanks

 

[ferdows]

hi
hfss is easier than CST for design and i suggested that
for wave port u define the length of port must 5 time grater than u micostrip line and height is 2 time grater u substrate
this antenna look simple why u want fabricated it?

 

[simazafrani]

Hi

for wave port u define the length of port must 5 time grater than u micostrip line and height is 2 time grater u substrate

From what u worte, my port definition ok...

this antenna look simple why u want fabricated it?

yup, the antenna look simple...How, this is part of my miniproject..so i have to present simulation n measurement result..

hfss is easier than CST for design and i suggested that

i will try to find this software...hopefully there will be free version for student usage...or at least trial...

Many thanks...