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A lot of interest was shown in the Club stand.those that didnt get along,missed out on a very good day

There would appear to be a need for information on discrete or stealth aerials. The R.S.G.B. does make available several publications to cover these needs. Some will query as to whether these ‘alternative’ aerials will work as well as a dipole. Certainly they will not compare with a beam but they are comparable to other lesser aerials. Your scribe has great faith in the magnetic loop. There are home-brew articles on these and commercial versions exist. Going for a bought out one will cost money; some of these stealth ae’s can be made very successfully. Oli’s mag loop (first try) was a length of " coax (using the outer screen), kept in a circular shape with two bamboo poles and a variable capacitor with slow motion drive. Another advantage, apart from no wire up in the air, is that the mag loop can be used at ground level with no detriment. I hope to do a scan of past sources and bring to your attention some of these alternative Ae’s.

The Arno Electtronica E-H Antennas [’I’ in the following refers to the reviewer; G3IHR]

The E-H antenna is one of several controversial small antennas that have appeared in recent years. The 40m and 20m E-H antennas reviewed here are manufactured in Europe under licence by Arno Elettronica in Italy.[Ted Hart,W5QJR, has made available a large body of constructional information on his website - www.eh-antenna.com] In essence, the E-H antenna comprises two metal cylinders which constitute a short dipole. These cylinders are fed via a phasing network located beneath the lower cylinder. The purpose of the phasing network is to cancel the phase shift between the applied voltage and the displacement current through the natural capacitance of the dipole, causing the E and H fields produced to be in phase. The E-H antenna in its present form is essentially a monoband device which has a wide SWR band-width (Ed. Unlike the mag loop), typically 400kHz between the 2:1 SWR points for the 7MHz model. The antennas are constructed on a fibre-glass cylinder which is enclosed within a second fibre-glass cylinder that provides protection from the weather. The whole assembly is robust and clamps are provided for fixing the assembly to a stubmast. A six-page document contains advice on installing the antenna and contains some advice about routing the feeder to reduce pick-up on the coax sheath. Before installing either antenna in its final position, I mounted it approximately 5m above ground and checked the SWR and bandwidth using an MFJ-259 analyser with its case grounded. The bandwidth of both antennas met the specifications easily.

In my opinion, there is no perfect way to review the performance of an antenna for amateur use. Testing under ideal conditions can produce very false impressions of how it might perform at a typical amateur suburban location. Accordingly, this review makes comparisons between my normal antennas - a full-size G5RV and a 12AVQ vertical - and the 40m and 20m E-H antennas. On 40m the G5RV returns the sort of performance one might reasonably expect from a dipole mounted at approximately a quarter-wave above ground.

THE 40m E-H ANTENNA The 40m E-H antenna was first mounted on a short stub pole approximately 20ft from both my house and my neighbour. Obviously its performance would improve as its height above ground was increased, but this is true of any antenna and it was felt that this position was not atypical of that where a small, discrete antenna had to be used. It was used in this position for several days and a number of QSOs were made with signal reports comparing well with the G5RV. However, I decided that a fairer comparison could be made if I temporarily replaced my 2m Yagi with this antenna at a height of 30ft and approximately 20ft from one end of the G5RV. The majority of the contacts used here only rely upon comparison of the received signal. So we can conclude from these tests that the E-H antenna performance was between 0.5 and 3.0 'S' points below the G5RV with a mean of 1.4 averaged. How did this result compare with operational experience? The majority of contacts on 40m during the review period have been inter-G and continental. On average, the difference was small but the standard deviation shows considerable variability. With the remainder of Europe, east beyond the Urals and south to Italy, Spain and Greece, north to Norway and Sweden very similar results were obtained. It is reasonable to conclude that on the longer distance paths, the E-H performance is on a par with the G5RV; on short paths, ie inter-G, it is likely to be lower than the G5RV. This is consistent with what one might expect comparing a horizontal and a vertical antenna.

THE 20m E-H ANTENNA It was mounted close to the site previously occupied by the 40m E-H antenna.; the received signal was compared with a 12AVQ vertical antenna, mounted at ground level approximately 25m from the shack. Where the opportunity arose, transmission comparisons were made between the two antennas also. The E-H antenna compared very favourably with the 12AVQ and often with the G5RV which is, of course, quite directional on this band. On receive its characteristics are almost identical with the 12AVQ, ie a considerable increase in solar noise as compared with the G5RV which exhibits a quiet background on 14MHz, and an improved response to stations over 500km. The same increase in solar noise was noted with the 7MHz E-H antenna suggesting that it has an additional high-angle lobe. The E-H appeared at all times to be omni-directional in the horizontal plane but the solar noise level at times was detrimental. In particular, VU2VJT was worked on the 12AVQ but was inaudible on the E-H. The caveats given for the 40m comparisons apply here too. The variation against the 12AVQ was less marked and the antenna held its own very well.

CONCLUSIONS To summarise, from an operational stand-point both of the E-H antennas performed extremely well as general-purpose antennas, exhibiting no significantly different performance to my normal antennas. They both exhibit characteristics that are similar to a ground-plane antenna or a vertical dipole, showing some enhanced low-angle radiation as compared with a horizontal antenna. Both antennas worked quite well at ground level but only compared favourably with the other antennas when operated under similar conditions, ie at a similar height and position with relation to surrounding objects. The nature of the above tests preclude any possibility of verifying the manufacturers claim of 0 to+2dB over a dipole. Where space is restricted I believe they will produce comparable or better results than a wire antenna that has to be bent to fit into a restricted space, eg a loft, or other 'stealth' antennas. The main disadvantage is that the E-H is a mono-band antenna. The E-H antenna is claimed to produce a better signal-to-noise ratio on receive than a conventional Hertzian antenna. I did not experience this on either band; the response to local noise was lower, but as noted above the level of solar noise was equal to that of my 12AVQ vertical. This antenna will I am sure be attractive to those amateurs who have little space or suffer from planning restrictions. In those situations, it is essential that RF can be piped around with minimal EMC problems. I understand that an 80m E-H antenna is available and a design for 160m is on the cards. I can imagine that mounting these at any height may pose significant problems due to their size. Nevertheless, it will be interesting to see how they perform on bands where lack of real estate poses an even greater problem.

144 Euros (approx £100) inc VAT. P&p extra

(Ref Rad Comms Sep 2003 pp 21 - 23)

Files Section

to download the files, Click on file .or right hand click on it,then choose "Save Target As"

How_to_build_your_EH_Antenna.pdf  This is the file refered to in news letter

index_files\VX-5&7R Interface.pdf modification file for the VX-5 & 7R (this file written by one of our club members)

HOW DO YOU CONVERT FREQ. INTO METRES ??????

Electromagnetic Waves travel at the speed of light .which is very close to 300  metres per Microsecond.

So to find the Wavelength of the Freq (Metre Band) devide 300 by the Freq.

So using the above formula

150khz = 300 devided by 0.15mhz = 2000 metres

21 mhz = 300 devided by 21mhz = 14.28 metres

144mhz = 300 devided by 144mhz = 2.12 metres

so using the above formula,2 Metres comes out at 2.12 metres

For Sale

2 x 18 element 70 cms beams

1 x 30 element 70 cms beam

all at 10 pounds each

contact Bob G1ONV 01643 863462