Stacked Antennas

I inherited some Comtelco Stacked antenna kits for 900mhz. They are two 900mhz yagi’s with a combiner which is supposed to give a gain of 15dBd or 17.15dBi.

Has anyone ever used stacked antennas? Performance?

We used a stacking kit with two 17db antennas. It got us from about -79 at the AP to about -75. The RSSI went from -80ish to about -72 at the subscriber end.

Performance seems pretty stable. Haven’t had a single complaint from the customer - they’ve been extremely pleased with the connection.

Stacking 2 identical yagis will give you a 3 db gain. Just like doubling your power out.

If you run full transmit power, it will make you illegal in the US. :shock:

Not for point to point links…

No, that’s not correct. The “no limit” rules works on 5.8 GHz and on 2.4 it works a bit different.

On 900MHz, it’s 8 watts total or 39db.

Now, what I’ve notice in my time is, “NO ONE CARES”.
But then again, you could be used as an example like this case … 874A1.html

In the 2.4 GHz I’ve seen ISP with 25 watts amps and 20 db sector. That will give you more than 2.5KW. The main difference I can see is , if it’s a big company they can’t do it. If it’s a small company or and end user why fine them?

I’m implying to break the rules, but I am very tired, very, on working with interference. The 2.4 GHz spectrum is abused, prostituted to it’s fully extend, it will happen with 900 MHz like it happen 9-10 years ago. Same will happen in the 5 GHz.

I have a problem with people going over the FCC set limitations on installs that will carry the signal long distances or on base stations. When you’re 120’+ in the air your signal will carry a long, long ways - especially on 900MHz.

We most certainly do not want to make a habit of going over FCC set limitations - they are there for a reason - fairness for everyone. However, the changes of it interfering with something in remote areas is very little, especially when the population density per square mile is less than 5 people. That, of course, is not an endorsement to break the rules.

For the record - the install we used the stacking kit on really needed a boost in the receive gain. After moving the antenna to a higher location, adding the stacking kit and adjusting the power accordingly it made a significant difference.

Just my $0.02.

I stand corrected. The point to point does not apply to 900mhz.

That being said, this particular situation uses Alvarion which only puts out 24dBm at the connector. This coupled with a 6" RG58 pigtail, 6’ Heliax Jumper a combiner and connectors plus an antenna with gain of 17dBi even as a stacked system should be within legal limits or close enough nobody will care.