Puzzled about different beam antennas

[k4zmi]

I notice that a Cushcraft 2 element 40mtr beam has a 22 ft boom and the Mosley 2 element 40mtr beam has a 28 ft boom, yet both beams have essentially the same db gain.

I am inclined to think that Mosley has a standard boom for several different models in order to cut costs. Most Mosley tri-band beams at best have 8 to 8.5 db gain, yet the Cushcraft X7 tri-bander has 12 to 13 db gain.

Mosley is quite expensive compared to other brands and do not have as much gain or front to back rejection. Other companies boast much higher figures with more compact antennas. Could they be using different figures and see gain and fb ratio differently than Mosley? What could actual gains signal wise be?

Need some positive thoughts on these issues

[k4zmi]

I notice that a Cushcraft 2 element 40mtr beam has a 22 ft boom and the Mosley 2 element 40mtr beam has a 28 ft boom, yet both beams have essentially the same db gain.

I am inclined to think that Mosley has a standard boom for several different models in order to cut costs. Most Mosley tri-band beams at best have 8 to 8.5 db gain, yet the Cushcraft X7 tri-bander has 12 to 13 db gain.

Mosley is quite expensive compared to other brands and do not have as much gain or front to back rejection. Other companies boast much higher figures with more compact antennas. Could they be using different figures and see gain and fb ratio differently than Mosley? What could actual gains signal wise be?

Need some positive thoughts on these issues

Please excuse the error in boom length of the Mosley 2 element 40 mtr, it is actually 24' Also, the 3 element beam has a boom of 36'. Would you believe the Mosley Pro 96-S all bander plus warc and 4 elements on 40 mtr has a boom length of 48 Ft?

[k9yli]

First read the HAND BOOK dissertation on beams. It would wear out a keyboard to answer the question completly.
A beam design is optimum at only one frequency.
Everything else is a compromise.
Band width, Beam width. physical size. gain, front to back ratio.
change anything and all the rest need changing too.

So any beam is a compromise of many things...
And the claims of manufacturers are suspect...