Intro Prototype 1 Prototype 2 Test Results

My Results



With my short (and easy) tests I deduce the EH lose about 10 dB versus my short 10 mt vertical with capacitive hat in the top;
10 db is a big amount of power, but remember we are using 2 small cylinder of 37,5 cm on 160 mt band;
my vertical performed better than a 40 mt long sloper, so, may be, loss versus full size dipole is not too much.

There seems to be something good;
May be optimizing something we can have more gain (or, better, we can lose less dB);
This antenna can be useful on the low band, expecially on 137 KHz (the EH cylinder should be 6 mt high with a 2mt diameter).
On the web I've seen an other similar antenna (ISOTRON), wich seems caming (as EH Antenna) from CFA antennas;
On the italian Radio Rivista (1995-1996) there were same informations about an "Antenna Toroidale" wich in same way remember the EH: will be interesting build and test one.
By the way, I think that my EH is not for Dxing; it will be useful for that radioamateur who have no possibility to install "long" antennas for low band, but want just to have local QSO or few contest-contact.


Other point: tuning;
I think it's not as simple as others say; I've used an MFJ259B which tells me all about the antenna, but the tuning was critical.
On the other side construction is easy;
I want suggest to you , when tuning, to connect the MFJ259B to the shack ground (if there's one). If not, EH will probably resonate higher (20-30 KHz).

Coaxial cable influence: inserting more coax cable, the resonance seems to vary a little; I suppose that's normal;
I don't know for certain if the line radiates or not; I've added two iron-powder coil forms back my TX and EH performance was unchanged. Then later I've added 2 big ferrite beads with a lot of turns on the roof (at the feed point of the EH) and all has changed. My signal was 3 S point weaker than before and S.W.R was very high.
I don't know if that loss is due to the changed resonance in EH (as I said before, outside the bandwidth performance goes down quickly).

Phasing theory: I don't want speak about that but, certainly, even with a wrong network EH performances were similar. May be it just needs better impedance matching?

Low noise: I don't know if that's true. With EH signals are lower, but at the same time also the floor noise is lower;
I've switched between EH and my 15 mt loop: with the loop signals were very poor but the S/N ratio was better;
I've heard more "local noise" with the EH: my TNC (modem) radiates some signals on 160 mt. With my vertical these were very weak while with the EH they became much much stronger.
Maybe EH hears all signals coming from a low angle better?

I would like to know other radioamateurs who have built and tested a EH antenna to have confirmation (or not) of my experiences (it's not important if EH is for 10-20 40 mt band or other).

These pages aim to make you aware of my experiences with EH: no more.
I'm not PRO or CON the EH antenna.


UPDATE 10/10/2002

In the last months I had the opportunity to test an original EH for 40 mt band;
well, I've tried the following:
I 've connected a small portable HF  receiver to the coaxial cable in my shack (20-30 mt) and tuned a strong signal on 40 mt band;
it was strong, (+ -  S9), but was dirty and noisy;
Then I've moved in my garden, where is the EH; I've disconnected the 20-25 mt cable and connected just a 10-12 mt coaxial cable (the same cable, but shorter, trought a double SO239);
I've connected the receiver  and the same signale was now clear.
I was not able to understand if signal was changed, but now it was clear;
Well, the same has occured with my 160 mt EH wich listen all noise in my shack: it ' s digital noise coming from PC, printers, TNC ecc.
That make me think that the coaxial cable  have some "influence" ...;
Then I've connected the small HF rx directly to the EH (just 5-10 cm of coaxial cable);
the signal tuned before was now weak (S1-3,)....

Next winter I want to test the following: I'll put up my 160 mt EH and connect it trought a 100-200 mt coaxial cable;
It's not very important for me if the coaxial cable radiate or not, but if I'll have better result (less than -10 db under the vertical) that will be nice !




73 de iz7ath, Talino Tribuzio