A comparison of 4m yagis using the MMANA simulator

By Marcel Pertus F5DQK

Introduction

My main interest in ham radio is sporadic-E DXing from 28 to 144MHz, and also dx-TV reception. Up to the year 2000, I made a few cross-band QSO's from 10m onto 4m, using an MMT144/70 transverter. This was not easy on 28.885MHz, which was more often used for 6m/10m crossband operations.

My home-made antennas at that time were:
a 50/70MHz dual-band dipole in the loft (2 dipoles 3cm apart and fed by the same SO239 connector.
an outdoor 50/70MHz double HB9CV (on the same boom) at 15m above ground.

I recently performed an MMANA simulation on this beam, which did not yield very good results, nevertheless it did work, and I had QSOs to GM (on FM), and ZB, and could hear many G stations and the 5B4CY beacon.

Job problems in 1999 forced me to sell my whole shack, (my MMT144/70 going to a GM station) and all my antenna farm from 28 to 1296 MHz.

But now that I have "no more job risks" and there are more countries QRV, I have returned to my original passions, especially 4 metre JT6M and Es DXing. My first thought was antennas: finding the best compromise between gain and boom length.

I decided after making my own opinion to communicate it to all hams especially those interested in four metres, and I think that this little article could also help hams in the UK and around Europe: I hope so!

Comparison table

After gathering information on all the 4m beams produced inside and outside the UK, and then analysing them in MMANA, based on details of element diameter, construction and boom length, I produced this following table:

Gain vs. boom length.

Marcel has produced a brief PowerPoint presentation (1.8Mb) on his use of the MMANA simulator for this project.

Comments

I did buy a Moonraker YG5-4, paying the £30 freight costs. Its gamma-match cannot be very well sealed, since this beam doesn’t work any more with good SWR! We must pay attention to this before installing or buying it!

The Trident 4M4 with its boom length of only 60cm more (and only 4 elements) gives immediately 0.9dB more forward gain. This would be my preferred choice, because a 3.2m boom is not too large. This is sold by Nevada Radio, but the great problem was that they charge an extra £175 for shipping for outside UK.

In contrast, Ron GW3YDX from Eagle Antennas quoted me a price of £45 for shipping outside the UK. The construction of these antennas (as seen on his web-page) is very robust, and N-type fitting is also offered. They have several models from 3 to 6 elements, and my choice would be the 5-element with a 3.8m boom length and 9.1dBd simulated gain.

Wimo from Germany sells only two ZX-yagi models: 3 and 6-eles. In my opinion, the former is too small and the latter too long, but freight to France is reasonable, priced at 34€ per yagi.

DK7ZB’s yagis are designs for home construction. Sadly, I don’t have enough time to do this right now, but perhaps in six months? (too late for this summer's Es!)

The HB9CV’s plus 2 directors were simulated after transposing the capacitor-less 6m Diamond A-504HB or the Comet CA-52HB4 to four. I have both of those here, but prefer Diamond’s more robust construction.