Dear research, please follow these four steps: 

1. Right-click the Infinite Sphere icon in the project tree, and then click Compute Antenna Parameters on the shortcut menu.The Antenna Parameters dialog box appears.

2. Under the Solutions tab, select the solution for which you want HFSS to compute antenna parameters.

3. Under the Intrinsic Variables tab, select the solved frequency point at which you want HFSS to compute antenna parameters.

The Antenna Parameters window appears. If the design includes ports, the following antenna parameters are listed:

Maximum intensity (Max U)

Peak directivity

Peak gain

Peak realized gain

Radiated power

Accepted power

Incident power

Radiation efficiency

4. Click More to view the following maximum far-field data:

X

Y

Z

Phi

Theta

LHCP

RHCP

Ludwig 3/X dominant

Ludwig 3/Y dominant

Good luck 

Check 3D pattern realized gain for maximum gain of the antenna. The color bar on left indicated what is the maximum gain. 

send me your hfss file and I simulate you gain

Dear research, please follow these four steps: 

1. Right-click the Infinite Sphere icon in the project tree, and then click Compute Antenna Parameters on the shortcut menu.The Antenna Parameters dialog box appears.

2. Under the Solutions tab, select the solution for which you want HFSS to compute antenna parameters.

3. Under the Intrinsic Variables tab, select the solved frequency point at which you want HFSS to compute antenna parameters.

The Antenna Parameters window appears. If the design includes ports, the following antenna parameters are listed:

Maximum intensity (Max U)

Peak directivity

Peak gain

Peak realized gain

Radiated power

Accepted power

Incident power

Radiation efficiency

4. Click More to view the following maximum far-field data:

X

Y

Z

Phi

Theta

LHCP

RHCP

Ludwig 3/X dominant

Ludwig 3/Y dominant

Good luck 

Dear researcher,

I received your message and I jointe you the concerning paper intitled "Design and Simulation by HFSS of a Slim UWB PIFA Antenna" .

If you see the paper, the radiation efficiency before slotting the antenna is 100% (figure 12)  and became 87% after slotting the antenna (figure 9).

the compromise concerning this change is "The improve- ment of bandwidth was accompanied by decreasing in gain and radiation efficiency"

the concerned paper  "Design and Simulation by HFSS of a Slim UWB PIFA Antenna"

In the same paper paragraph 2 "UWB FCC requirements "

Ultra-wideband refers to radio technology with a bandwidth exceeding the lesser of 500 MHz

OR

20% of the arithmetic center frequency (called also fractional bandwidth)

Also, Even if the radiation efficiency that is the ratio of the radiated power to the accepted power given is theoretically in maximum 100%, in simulation, it can be more if you didn't define correctly the boundary limits or the port to be displayed.

Dear,

You get it in 3D pattern realized gain for maximum gain of the antenna.

Regards,

As Sir ABdelhakim El Ouadih said right point

Dear N.A. JAN 

You just send me your HFSS model and then I will do that for you. Send it to the same e-mail we normally contact.

Rgds,

Issa.

what is the range of radiation efficiency which is pratically accepeted