antenna design for simple HF shore station for tradisional fisherman
i wanna build an antenna at frequency 6.363 MHz (maritime HF frequency),,,it will be the seashore station for traditional fisherman communication,,
i wanna build the directional antenna that can cover the wide-seashore and have less back lobe,,the problem is how to make antenna with simple and compact design otherwise the frequency center at 6.363 MHz and have wavelength about 47,2 m..but not all the seashore have space for built antenna as large as that. so i wanna built antenna under 10 meter length, have the wide direction along the seashore..how the best for it,,design for the antenna,loading coils and the reflector..
thx before,,sincerely yours..
If you have a whip aerial, you can add base inductance to make it appear longer. So you have two of these and add the signal from each of them via a phase shifting network. So you adjust the distance between them to be as big as possible (ideally 1/4 wavelength), then adjust the phasing to peak the signal in one direction and cancel the signal from the opposite direction.
Frank
If the frequency is always 6.363MHz, the most compact but efficient antenna would be a tuned magnetic loop. Their advantage is small size, high efficiency and they are directional, their disadvantage, if you use them for transmitting is they produce very high voltages at the tuning point (possibly several KV !). Do a search on magnetic loops, it should turn up several design pages.
Brian.
thanks for the recommendation,,,about the magnetic loop..how to wider the direction of the antenna?is there any link that show the radiation pattern of the antenna?or the simulation with NEC or HFSS?
thx
I have never used one myself although I considered it for transmitting because I have little space for a large antenna here. I think the radiation pattern is similar to a center fed dipole, in other words, if you looked from above, there would be two lobes extending at right angles to the wire of the loop. It might be possible to phase out one lobe by using a second magnetic loop but I have no experience in this field.
Brian.
how about its efficiency?how to boost its efficiency at my center frequency(6.363)...consider that it uses the variable capasitor..
thx
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is there any link about complete magnetics loop antenna..from its radiation pattern, the simulation until the material that builds the antenna,,thx again and again,,
Magnetic Loop Antennas, Magnetic Loop Info, How to Build A Magnetic Loop, W2BRI Loops
AA5TB - Small Loop Antennas
Magnetic Loop Antenna - Antennas: Magnetic Loop
is there any reference about its radiation pattern and design in hfss, nec or mmna gal,,,?thx before
hi
this kind of antenna usually active antenna and so u cant design them normally
These loop antennas are widely used as "normal" antennas (transmit & receive).
hi
when i said it can't made normally i mean u can't simulated in hfss or other software
Of course you can.
so,,is there any example of the design with the simulation?thx
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how to get the better efficiency at my center frequency when it is receive or transmit?
hi u never can simulation small size of this antenna in hfss or other software for more information read handbook of antenna of johnson and practical antenna handbook of Carr
do you have any link to download those books?thx
See NEC simulation in my post #7, second link
hi
i think u can download them from gigapedia.org
the magnetic loop antenna have two type,,the transmitting and the receiving,,is it possible to get the antenna performance as good as when it transmit and when it is receive the signal?
is it any reference to build the small two element quad loop antenna?
The most efficent method, given your 10mtr height is the answer given by Chuckey, a pair of 1/4 wave verticals (estimated to be 7.8m high) with a phase shift. The phase shift can be arranged by using cable to cause delay. Magnetic loops are great and efficent, however one big issue is narrowbandedness. Small changes is C or L can result in being off tune, whereas with verticals, band width is much wider. J Carr Practical Antenna Hand book is one place where this is discussed simply.
i have simulated the dipole antena with the vertical position,and it has 2.9 m long,,,with the coil about 47 uH..but the weak point of this antenna is the efficiency of radiation (measured about 4% according tu the 4nec2 simulator)..is it possible to raise up its efficiency?with dimension about just 3 metres?how to get the good efficiency and not too long antenna,,,because the antenna will be made with aluminium..thx