ARLA/CLUSTER: HB9Q com pequenas antenas yagis LFA de 2 elementos, demonstra a possibilidade de QSO´s via Rebote Lunar segundo Justin (G0KSC).

[João Costa > CT1FBF]

HB9Q with LFA Yagis make EME possible to small antenna stations

Are you that guy that tells everyone 'you work the World on a wire and
don't need a Yagi'?

In most cases, it is the Yagi belonging to the guy at the other end of the
QSO that is doing all the work, pushing and pulling on your behalf
otherwise, that QSO might not happen.

I recall many years ago when that realisation set in for me. The first time
I installed a Yagi on HF and then for the first time, able to hear and work
stations in the USA with wires that I had not heard before.

*HB9Q* has made it possible for many stations with very small Yagis to work
EME (Earth Moon Earth). In some cases, a 2 element Yagi has been used and
in at least one case, a simple dipole.

At HB9Q a 10m dish is in use so the gain and potential of this arrangement
is huge. However, the capabilities of this dish were not always as they are
these days.

Several years ago, Dan the station owner at HB9Q contacted me to explore
new options for feeding on 20m and 70cms. Yagis were in use at the feed
point, pointing into the dish but unwanted noise and birdies where often
present on receive. After much discussion and modelling, we decided on 2
sets of 4 element LFA Yagis for 2m which were horizontally stacked and
phased (one set horizontal, one set vertical) and a X-pol 7el (14el total)
LFA Yagi for 70cms.

All antennas would be rear mounted and the 70cms X-pol rotated 45 degrees
in order not to be in the same plane as either set of the 2m antennas to
avoid the 'third harmonic issues' that exist between 2m and 70cms. Not
aware of the associated issues of third harmonic relationships in Yagis?
Contact G0KSC.

The result? Birdies gone, unwanted noise reduced and the performance you
have seen from HB9Q in the last few years. The combination of HIGHLY
SUPPRESSED pattern optimisation, the importance of a FULLY CLOSED LOOP
driven element within the Yagis and ‘UNDER-STACKING’ to avoid side lobes
outside of the dish face are all part of the reason the HB9Q project has
been a great success and allowed small station hams to work off of the moon.

Have a special requirement for your VHF/UHF needs? Let me know and we can
work on it together.

*Justin G0KSC*

www.g0ksc.co.uk

www.innovantennas.com
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