STEVE NICHOLS, G0KYA ♦ E-MAIL: STEVE@INFOTECHCOMMS.CO.UK
JULY 2011 ♦ RADCOM
The I-PRO Home from Pro Antennas
A centre-fed vertical dipole with capacity hat end loading
with a heavy duty galvanised mounting bracket, suitable for posts of between 1.5”–2”. Once mounted on a suitable stake (not supplied) it actually sits just under 6m tall and weighs in at 4.5kg. If the antennalooks familiar, it is very similar to Carl's Dual Beam Pro reviewed in May's RadCom. The difference being that this one is ground mounted and, being vertical, it is omnidirectional. Aerospace alloys are used throughout, as are non-corrosive stainless steel fittings. Solid GRP rod is used for the important insulating sections. This material provides excellent dielectric properties with great structuralstrength. The antenna will cover all five amateur bands from 20m-10m. If you have an external ATU it can also be persuaded to cover 40m and 30m (an average internal ATU will not handle the high SWR the antenna presents on these bands.) There is no reason why the antenna shouldn’t be used for short wave listening either, from about 5-30MHz.
The IPro Home - if installing it permanently werecommend guying.
VERTICAL DIPOLE. The I-Pro Home Multiband HF Vertical Antenna, to give it its full name, is the latest product from Carl Kidd, G4GTW, at Pro Antennas. Having tested his DMV Pro, I-Pro Traveller and Dual Beam Pro antennas previously, I was keen to see what this one had to offer. The antenna is a centre-fed vertical dipole with capacity hat end loading, looking like an H on itsside. Capacity hat loading was chosen
to keep the inductive loading to a minimum and so reduce losses. It is designed to be non resonant on all of the amateur bands. A large un-un transformer (of unspecified impedance transformation) is fitted to the centre of the dipole, which reduces the resultant SWR down to something your rig’s internal ATU can handle. The maximum power is 400W PEP. Theantenna is 5m long, with the top and bottom elements spanning 2.5m. It comes
HARDWARE. The I-Pro Home comes in two boxes – one containing the hardware and balun, the other being a long cardboard tube with the elements. On unpacking everything it was time to study the instructions – carefully. Do take the time to read them as it is very easy to put the antenna together incorrectly (as I found out).First you attach the un-un to the centre insulator and vertical elements. Then you bolt on the aluminium support rod, which holds the un-un firmly with a worm-drive (Jubilee) clip. You then add the capacitive end-loading elements at each end. I managed to put the whole thing together in an hour, but I did have to remove and reattach the un-un as I had it on the wrong side of the support rod.Having assembled the antenna you then attach the coax, via a PL259, with suitable weatherproofing such as self-amalgamating tape and drop it onto the mounting post. The instructions say that for all-weather use the antenna should be guyed (guys not supplied). I would endorse this – if leaving it up for more than a few hours, guying with nylon cord is essential as the antenna is quite top-heavy. Thecoax has to be arranged to come away from the antenna at about 45°. This minimises interaction. On connecting the antenna up to about 20m of Mini-8 coax I found the raw SWR figures as shown in the table. As you can see, an internal ATU should be able to find a 1:1 match on all of the bands 14MHz – 29MHz. My rig could also match 10MHz, but I know
RADCOM ♦ JULY 2011
A close up of theun-un at the feed point.
The I-Pro Home is a very low angle radiator and this is best demonstrated during greyline periods. A small reservation is that the reviewer missed the opportunity to exploit this property against the horizontal wire antennas. However, I am pleased my centre feed arrangement was shown to be much more efficient without the requirement of radials...