I am almost to the end of september article 9A4ZZ BIPOLE ANTENNA translated into English and you will be able to read it on my web site web.hamradio.hr/9a4zzVK6WAX wrote:I'm attempting to convert a PDF about this antenna from Croatian into English and it's not making much sense from the literal Google translation.
Does anyone have any experience with this kind of wound dipole or can point me in the direction of further information?
The drawing of the antenna looks like this: The link to the PDF (1.1MB, in Croatian) with more pictures is:
http://www.hamradio.hr/9a4zz/files/9A4Z ... ANTENA.pdf
Another amateur S52ST, has more information but again not in English (Slovenian)
http://www.trputec.com/s52st/bipol/bipole.htm
A 40m version would fit in my roof space until I can get the council onside about putting something above the roof.
Thanks
Andrew
WB5WPA wrote:Funny thing, this style antenna - the max response is off the *ends* and not broadside
as with a normal 1/2 wavelength (I will call it "magnetic") dipole.
When mounted horizontally, this 'response' can be observed on receive with noise nulls
off the broadside and peaks off the ends. Same response same on xmit.
For a quick xmit test a portable radio was placed across the yard and a low-power signal
generator fed the single input coupling loop 'inserted' into the tuning coil and the antenna
was 'rotated'.
This behavior leads one (me) to think this antenna respond to a propagated differential
E-field like a tuned loop responds to differential mag field.
Even mounted one vertical and did some WSPR comparisons on 40 meters.
One I put together mounted horizontally last year and tested for a bit:
http://www.qsl.net/wb5wpa/EHantenna/EH_Mark_3_Horz/
Note the use of a single turn feed loop inserted into the coil. More or less insertion
controls coupling and the match (SWR reading).
Jim WB5WPA
Dear friends aim of this article is to present 9A4ZZ Bipole antenna to each radio amateur could do. The theory of operation of this antenna is very complex and has shown the most simple way, more than that I can not show you. This is a practical solution for those who do not have space for a standard antenna and any of an opening for experiments.On my web site you have another article about my 9A4ZZ Bipole which are worked by radio amateurs.VK2AVR wrote:Thanks Mladen, that was an interesting read.
I wonder how it compares with a magloop for efficiency? Of course, it is not easy to make objective measurements because a lot of environmental factors need to be taken into account.
The near-field noise characteristics of the bipole will be different to a magloop. Being an E-field antenna it may be a bit more susceptible to extreme near field noise than a H-field antenna (magloop). However, when you look at the impedance of both E-field and H-field antennas as distance increases, though, magloops become E-field dominant at moderate distances from the antenna. So it will probably depend on the exact sources of interference in each situation, sometimes one antenna will just seem to work better than the other.
Kinda tempted to build a magloop and a bipole and play with them.
VA6ARC wrote:Thanks 9A4ZZ for posting the english translation, makes it so much easier to understand.
I am in the process of constructing a 20m bipole and will be able to compare it to my MFJ mag loop.
Have constructed a 40m bipole and did make contact with a station in the US, but do not have the antenna tuned fully yet.
Rather than using a secondary 25 turn winding to feed the antenna, I have tried taping the main coil using the center 25 turns. It appears to work easier in some respects as the antennas resonant frequency is not changed as much as it is when adding or removing turns in the coupling coil.
Also the usable band width is higher when taping the main coil vs using the coupling coil.
Am using a Rig Expert AA-230 to tune the antenna.
Tuning the antenna can be a bit like a dog chasing its tail, but seems quite logical.
JX needs to be 0 at the resonant frequency.
Negative Jx value - Too much capacitance ( shorten tube, space tubes further apart)
Positive Jx value - Too much inductance ( reduce turns in main coil )
Adjusting either changes your resonant frequency though.
I have not yet tried using the metal band to alter inductance.
73
Roger Yoneliunas VA6ARC
Please indulge us in this matter Mladen by explaining since we are supposed to be technically enlightened as Amateur Radio operators.The theory of operation of this antenna is very complex and has shown the most simple way, more than that I can not show you.