Point to point (yagi vs. parabolic dish vs. grid dish)

8 posts / 0 new

Tue, 11/08/2016 - 10:04

km5l

Anyone have a comment on which would be better for a highly directional link? Say I'm going to use a Rocket radio for instance with an external antenna.

I have the following yagi from a different project: http://www.ebay.com/itm/2-4GHz-20dBi-Yagi-802-11b-g-WiFi-Antenna-RP-SMA-...

It is said to be 20 dbi gain.

If I compare to this grid antenna: http://www.ebay.com/itm/Premiertek-Outdoor-2-4GHz-24dBi-Directional-High...

The antenna is said to have 24 dbi of gain.

Then there's this: http://www.ebay.com/itm/Ubiquiti-RocketDish-2-4Ghz-24dbi-AirMax-2x2-PtP-...

Also said to have 24 dbi of gain

So, is it this simple of a comparison? Anyone compared in reality?

73,
Patrick KM5L

Tue, 11/08/2016 - 10:13

K6AH

Go for the dish...

The RocketDish is the only MIMO antenna in the mix. I wouldn't mess with the others. This is also the only antenna you've listed that'll accommodate the Rocket's two antenna ports. You will find other posts on the forum describing the benefits of MIMO.(reliability, data throughout, etc.). Ubiquiti now makes a new light-weight, less expensive RocketDish (look for the "-LW" in the model number).

BTW, I haven't actually used one myself, but I have heard from more than one ham that, that particular yagi is pretty worthless.

Andre

Sun, 01/08/2017 - 23:13

(Reply to #2) #3

w7rej

Ditto, yagis are worthless

In fact everyone I've tried for regular wifi wound up being junk.

Tue, 11/08/2016 - 10:51

n1cz

Maybe my thinking is too

Maybe my thinking is too retro, but would using 2 grid dishes ata node (for mimo) give the opportunity of polarization and/or space diversity as needed?
-Jeff N1CZ

Tue, 11/08/2016 - 11:12

(Reply to #4) #5

K5DLQ

I would never recommend two

I would never recommend two single polarity antennas in place of a true mimo antenna. You'll end up spending more money after you decide to throw away the 2 antennas and buy the true mimo.

Tue, 11/08/2016 - 11:32

n1cz

@K5DLQ Nice shot from the hip

@K5DLQ Nice shot from the hip.

I'm too lazy to dig into the math of the physics for now, but I am pretty sure that the packaged MIMO versus separate antennas are application dependent.

-Jeff N1CZ

Wed, 11/09/2016 - 20:59

(Reply to #6) #7

AE6XE

2 independent antennas are

2 independent antennas are going to have cross interference more than when they are designed together in one physical package. In MIMO, the MO = Multiple Out means sending different data streams at the same time out each antenna/polarization and thus different RF signals on each antenna to double the possible data rate. Any increase in cross-interference will result in lower performance, possibly even never achieving the 2x data rate (MCS8 to MCS15) options with 2 data streams.

Tue, 11/08/2016 - 12:40

n7ie

2 Parabolics

Hi, Jeff. I tried two parabolics back in the Linksys days. Not too much success and miserable to deploy. I much prefer the MIMO Ubiquiti line. 73 .. .

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