Need Help On Directional Antenna

hotwhiskey

Hi!

Please i need your help on directional Antenna as my coverage drops from HSDPA to 3G alot and coverage is about two bars.

I was looking at these two options below and can someone please explain whats the difference in the different size's of GHz and dBi mean. If anyone has any views or recommendations in what to buy glad to hear.

http://cgi.ebay.ie/ws/eBayISAPI.dll?ViewItem&Item=380299387648&Category=61816&_trkparms=algo%3DLVI%26its%3DI%26otn%3D2

http://cgi.ebay.ie/TP-Link-2-4GHz-24dBi-Out-Door-Grid-Parabolic-Antenna-/200555100420?pt=UK_Computing_Networking_SM&hash=item2eb203f904

Many thanks for your help.

watty

3G/HSPA phone network is 2.1GHz

Those are both aerials for outdoor bridging of WiFi. No use at all for Mobile/3G/HSPA

bigger number dBi or dBd is better

0 dBd = 2.2dBi
3 dBd = 5.2dBi

dBd = Compared to basic dipole aerial
dBi = Compared to a hypothetical impossible to make Isotropic Aerial

dB = log scale.
3dB = x2 signal
-3dB = 1/2 signal
6dB = x4 signal
-6dB = 1/4 signal

A double distance results in 1/4 distance. Inverse Square Law.

hotwhiskey

watty wrote: »

3G/HSPA phone network is 2.1GHz

Those are both aerials for outdoor bridging of WiFi. No use at all for Mobile/3G/HSPA

bigger number dBi or dBd is better

0 dBd = 2.2dBi
3 dBd = 5.2dBi

dBd = Compared to basic dipole aerial
dBi = Compared to a hypothetical impossible to make Isotropic Aerial

dB = log scale.
3dB = x2 signal
-3dB = 1/2 signal
6dB = x4 signal
-6dB = 1/4 signal

A double distance results in 1/4 distance. Inverse Square Law.

Thanks watty for the info.:)

watty

Engineers often use dBd figures. (how much better than a "basic aerial", dipole is).

Marketing departments like dBi figures because those are always +2.2