Stacked Antenna Gain and two or more elements in an array


This chart gives the additional  gain that can be expected from combining two identical antennas into a broadside array such as two dipoles or two Yagis or two verticals. For two elements  1/4 wave spacing only gives 1 dB gain but 1/2 wave spacing gives almost 4 dB with a maximum of almost 5 dB possible with 0.6 wave spacing. This chart and similar charts for broadside and collinear phased elements have appeared in most of the good antenna manuals for at least over 70 years. One of my oldest antenna books is dated 1949 and has the same information pertaining only to two elements whereas this chart goes from 2 to 16. Note however that significant gain increases are only shown for 2, 3, 4, 6 8, 12 and 16 elements.The largest single element increase (5 dB)  being from 1 to 2 elements. To get another 5 dB increase you must go from 2 to 6 elements. From there you must go for 6 to 16 for that same 5 dB increase.  Such is typical of increasing antenna gain. 
With a Yagi there is a similar such increase when adding the second element. As can be seen with the chart below going from 2 to 4 elements (doubling the size oof the Yagi) equates to 3 dB.In like manner doubling again (4 to 8 elements) yields another 3 dB. With the Yagi the gain also depends on boom length as well as the number and length of elements. This chart shows what is possible not necessarily what will easily be obtained. 





Comments

Post a Comment

Popular posts from this blog

Some basic antenna info

  Antenna thoughts August 2025 If one knows the basics of antennas then it becomes easy to choose what antenna is best for you. There is no one “best” antenna. There are very good antennas of course but even a very good antenna is not going to be right for all uses. I will discuss some antenna basics here and give some “rule of thumb” guidelines on how to think about antennas.  The halfwave dipole can be considered the basic building block of antennas. I think understanding the dipole is the key to understanding antennas. Also for antennas we need to think in terms of wavelength, not feet or meters.  For example a dipole 1/2 wavelength long and 1/2 wavelength high above ground is an excellent antenna. It has a gain of about 8dBi off the broadsides. It has a slight reduction in signal strength off the two ends. It’s peak radiation ( off the sides) is centered at about 30 degrees. The actual radiation is rather broad from about 15 to 45 degrees and gradually drops off above...
Read more

Half Square Antennas

 I have had half square antennas on 80, 40 and 20 meters. In all cases the top wire (spacing) was one-half  wave length long on the band I built it for. The half square is not a multiband antenna. My results were that the 80 meter antenna was the best antenna I ever had ( except maybe my full size 4 element 20 meter monobander)! The top wire was at about 60 feet or so. On 40 meters the Half Square antenna worked but not nearly as well as my 40 meter dipole in that it seemed to have the same gain in Europe but a more narrow pattern resulting in deeper nulls of the side than the dipole which was at about 35 feet. On 20 meters any full size (halfwave) dipole or end fed is hands down at least an S unit better if it is a halfwave (32 feet) or more high! I model a lot with EZNEC and the EZNEC results were almost exactly what I saw in practice. Any dipole or halfwave wire will have a gain of about 8 dBi if anywhere near a halfwave high. Any vertical over real earth will have maybe 0 ...
Read more

RADIATION FROM ANTENNAS

Image
 Radiation from Antennas Evaluating radiation from antennas is not widely understood. My intention is to attempt to simplify this misunderstood concept. I will use the term wire but it could actually be any conductor normally used in antenna construction . I will also use the term amp or ampere to be current flow.  Radiation from a piece of wire (antenna) is simply proportional to the amount of current flowing in that wire. It is also proportional to the length of that wire. If the wire length is measured in feet and the current in amperes we can do some comparisons.  I will start very basic to introduce what may be a new concept to many. First of all , if one amp of current flows in a piece of wire one foot long that will result in less radiation than if we have one amp flowing in a wire two feet long. I think that is easy to understand. We have a term for current flowing in a wire. That is feet-amperes . If you take the length of the wire and multiply it by the amount...
Read more