I've read on this site that folks have experienced range of 10 miles between a 24 db parabolic and a 14 db yagi. I've also read of 7 mile range when using a pair of 11 db omnis.

Is it difficult to aim two 24 db parabolic antennas at each other accurately over 10 miles? If so, does the effort required to aim and keep the connection make something like a 19 db rootenna a more practical antenna?

I'd appreciate any advice on antenna selection that folks might have.

Thanks & 73,

Mark KV4I

Antenna selection and microwave paths are a topic that could fill a book. The place to start is to do a path survey between the points you are trying to link. This includes doing a check of the RF on the air at each end of the link so you know who / what else is on the air in the location. For discussion, links may be divided between point to point links and “illuminating an area”, with an omni. There are many variations on the themes. If you are in a populated area, you may need to consider directional antennas for links of a mile or more, depending on what else is on the air in your area. For point to point links, we generally recommend horizontal polarization to get 30 dB of isolation from the generally vertical consumer AP units on 2.4 GHz. If you have a dense cluster of nodes in a grid / mesh configuration you can use omnis if the units are close enough. The general concept of a mesh is to use low power radios and have a lot of them close to each other. That way none of the radios is putting out a signal that is much stronger than needed to reach the next node. Consider point to point nodes linking isolated “pocket” mesh networks. When you start you may not have many nodes in your area and most, if not all may be point to point nodes. The description of 11 dB omnis linking at 7 miles was to show what can be done in an area that has almost no RF in the area other than the mesh nodes. You should not expect this range in a city full of thousands of consumer AP units on the air. Directional antennas will exclude a large number of potentially interfering signals from the input of the radio, simply due to the path for which they are sensitive. This is a huge help. The description of the 10 mile link with the 24dB dish and the 14 dB yaggi was over a very densely populated area of Austin, Texas with thousands of AP units on the air, cordless phones, baby monitor wireless cameras on 2.4 GHz and microwave ovens. The path and the high gain antennas allowed us to shoot over the other systems and link without the need for any RF amplifiers. If you have 10 dB of S/N ratio, or more, then the absolute signal level is not all that important. A directional antenna cuts out a lot of “noise” by excluding signals not in its pattern / path. This broadband microwave mesh work is a finesse thing, not brute force techniques. Put your signal where you want it / need it. If you have many close by mesh nodes, all can use omnis to great effect. If you are going for ½ mile or more, consider directional antennas aimed at another node. We discourage putting up an omni with a big RF amp and simply warming the vegetation in your area with QRM. Find a path to another node and pick and antenna that helps you reach it. One “pocket mesh network” can be linked to another collection of mesh nodes (pocket network) with a well placed point to point link. HSMM-MESH(tm) was intended as a rapidly deployable tactical network. It can be used for fixed point to point links or even mobile systems. Several of us in Austin have mesh nodes in our vehicles. That way when we pull up to a mesh equipped location, such as the Red Cross we can join the local mesh from the parking lot and get up to speed with what is going on, without having to enter the building. Mobile mesh antennas are another discussion. -Glenn KD5MFW

I  think a multi directional antenna is also a good option for getting good signal. Because this multi directional antenna works to transmit signals from multiple directions.

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