So a new antenna development plan has started.
The design policy is as follows. :-)
Therefore, the merit of hentenna is energized.
Of course, a certain kind of hope for the loop antenna which might be unscientific is considered enough. ;-) hi.
Refer to upper right figure for the structure (unit=m) of the short boom and narrow width type.
The height is 3.02m, and it's equal in all elements.
As for the horizontal element is fixed to the boom, the "L" type aluminum material is assumed. And Input to MMPC is as 15.6mm in the diameter.
If you use the one of 20mm+20mm or 12.5mm+25mm for "L", it might be OK.
Other parts are plain copper wires of 2mm in the diameter.
Two booms are 3m aluminum pipe which can be easily obtained at DIY shop.
The table above is the characteristic with frequency by the calculation of MMPC.
Right figure is the beam pattern of this antenna compared with 5el-F9FT (50.3MHz, above real-ground). In this simulation, the mast 7.5m in height is assumed.
The unit of the gain is dBd as gain to dipole in free-space. The beam pattern in the one of short booms are mostly same.
On the other hand, the gain of he4kpi_N is 14.41dBd, 7.5m from the ground. If 9.4m mast is used, its gain reaches 14.74dBd but is defeated by 8el-Yagi about 1.2dB.
What a indescribable difference 1.2dB! It can be explained if the antenna has been actually manufactured and compared. A certain person says there's no difference, and another person says that is great difference.
It is difficult to increase the gain 1.2dB for this class of the boomlength. The difference of the gain is only 1.2dB though the difference of boomlength is as long as three times. May it be permitted?
Yes, so I decided to design and calculate about the short boom antenna.
Left figure is a comparison between 4el-Hentenna and 8el-Yagi on top of the mast 9.4m height.
he4kpi_L(LongBoom) is a version which has extended boomlength to make the gain approach 8el-Yagi even in some measure.
Its gain on 7.5m mast is -0.78dB compared with 8el-Yagi though the bandwidth is narrow, and -0.33dB on 9.4m mast. It fights bravely, don't you think so?
If it has 5 elements, this hentenna may completely defeat 8el-Yagi on the same mast. However, the structure of this antenna is more complex than Yagi. In this band, it is not desirable situation that increasing the element.
I can do nothing but admit the Yagi is excellent.
As for the structure, it is so easy, and the calculation time is so short. :-)
Therefore, many company-made-Yagi is marketed. And a lot of people buy it more easily and QRV, though its easiness is definitely good.
Well, this antenna has not been completed yet. I've already found materials for this antenna in the DIY shop, but have the problem that how make it. Anyway, there is not a meaning without actually manufacturing. Because we're amateur radio engineer, you know.
I planed which type making, and finally decided to make a short boom and narrow width one (he4kpi_N).
Why narrow? Because a wide type one exceeds the width of my automobile. :-p
Of course, the weight of the antenna is lighter a little. This is exactly the one because of outdoor-QRV.
Recently I obtained the data of Create Design's 6el.-Yagi and had calculated it. The output for result of its gain in the free space is 11.2dBi. And my he4kpi_N has 11.4dBi, so joyously it win in simulation. However in actual??
TO BE CONTINUED