Tuesday, August 20, 2019

HF portable the simple way

One of the most enjoyable facets of amateur radio is operating portable. You may live in an area plagued with electrical interference, antenna space restrictions or dwell in an 'RF hole'. In such cases, portable operation gets you contacts not possible from home.

While not a substitute for proper RFDS or Marine equipment, amateur radio can add to the enjoyment of the trip on holidays and excursions. And the portable communications capability may be useful in emergencies.

Philosophy and Objectives

A weighty heading. But it's worth thinking about before you set off. Why are you going? What do you want to get out of it? And will the results be worth the chance of getting cold, wet, sunburnt or bogged?

I once did Field Day with a club where, despite the large number of helpers, it took hours to set up and dismantle the truly impressive portable station. Others spend months (and thousands of dollars) kitting out vehicles specially for portable use. There is no denying the effectiveness of such stations in earning high contest scores or setting microwave records.

Another approach to portable operating emphasises low cost, low power and quick setup. It won't win contests but there are other benefits. 'Minimum QRP', as I sometimes call it has a 'grab and go' spontanaety with little preparation or setup time required. And there's a certain beauty and satisfaction in getting good results from simplicity.

I also prefer HF portable over VHF and UHF. For several reasons. VHF and UHF are generally quieter and yield fewer contacts. And, especially on SSB, few progress much beyond a signal report. HF, particuarly the lower bands, is more congenial. My home location also plays a role; being a short walk to water but some distance from hills further adds to HF's appeal.

You may be different. If you're more technical, more elevated but less conversational, then VHF / UHF / microwaves may hold more interest. Long-distance VHF, UHF and particularly microwave contacts can make up in quality what they lack in quantity. This is especially if made on home-made equipment; something more common in the gigahertz range.

For this article I'll guess that you want to go portable, get on air and talk to a range of people. Right now it doesn't matter much where they are, but you do want to be heard and for there to be people around when you set up. HF is best for these purposes and is concentrated on here.


If escaping interference or antenna size restrictions at home, any open area such as a park or beach will be worthwhile. However some sites are better than others for various reasons.Things to think about when choosing a site include:

* Availability of tall trees with branches in the clear (for supporting HF wire antennas)* Availability of fences or metal railings (for earthing and tying telescopic antenna masts to)* Sloping ground and/or water in favoured transmitting directions* Sufficient room to erect masts and wires without getting in the way of other users* Distance from power lines and other potential man made interference sources* General site amenity. Eg shade, shelter from wind and rain, decks/tables/seating, lighting, etc* Ease and availability of access. If driving, how near can you get to the favoured operating position? And if it's a park, do the gates shut at night?* Proximity to home

The relative importance of these factors will vary according to the bands used, and the type and distance of contacts desired. If you're into DXing you may be willing to go for a further or less comfortable site if it means lower noise, better ground slope or water in the chosen direction. More on this later.


You can often get by with just one band, though another one or two improves operating flexibility and range of contacts. Forty metres is a good all-round band where there's many hams within 300 to 1000km, allowing contacts at most times. Add 20 metres if you're operating mostly during the day. 40 metres provides easy contacts up to about 1000km, increasing to 3000km around dusk. 20 metres isn't so good for closer in but comes good over distances of 1000 - 3000km and worldwide for multi-hop. Antennas for both bands are easy to build and not too large.

At certain times and places other band come into their own. Examples include 80 metres (evenings), 160 metres AM (ground wave during the day), 10 metres (Summer sporadic E or DX openings) and 17 metres (when there's a major contest on 20 metres). If you're up for a challenge, consider dawn or dusk greyline DX on the lower HF bands. More on the properties of various bands in the Foundation guide to frequencies and at QRP activity by band.


A half wavelength of wire (20 metres on 40 metres or 10 metres on 20 metres) is the basic building block for HF portable antennas. Don't believe me? Jam a quarter wavelength of wire into your antenna socket and try to make contacts. You'll get some but adding another quarter wave to the transceiver's ground should improve results.

The main differences are how you support it, how you orient it and how you feed it. The method chosen depends on what's most convenient and the types of contacts desired. Below I describe the variants most useful for portable operating.

* Centre fed half wave horizontal dipole. Take your half wavelength of wire, fold it and cut into two equal lengths. Attach any length of feedline to the centre. String the antenna ends between two trees and have the feedline hanging down. If the feeder is coaxial cable you'll have an antenna efficient for one band and won't need an antenna coupling unit. Whereas with open wire the antenna will operate efficiently on multiple bands but will need an antenna coupling unit. The basic half wave dipole will perform well up to medium distances, with height an advantage for longer distance contacts.

* Inverted vee dipole. Everthing's the same as the dipole above. The difference is that instead of hoping there's two trees spaced just the right distance apart, you support it at its centre. The ends are tied off to lower trees or fence posts. Again good for reliable HF contacts up to a few thousand kilometres, with longer distance DX very possible.

* Vertical dipole Again the centre fed dipole is used unchanged. But this time you support one end from a high support so that the radiating element is vertical. The feedline must be brought off to the side, as near as 90 degrees as possible from the centre of the antenna. A vertical dipole is difficult to arrange on 40 metres as a 20 metre high support is needed. However they're much easier on 20 metres as only a 10 metre support (such as a lightweight squid pole) will suffice.Especially if used over a conductive ground, such as salt water, a vertical dipole will outperform a horizontal dipole for long distance contacts because of its lower angle of radiation. Because I normally operate near salt water, I've become a big fan of vertical dipoles for 20 metre QRP DXing. I should warn you that they can be noisy on receive, but this might be a signal that it's time to try a quieter location.

* End fed inverted vee. Here's where we ditch the bulky coax feedline and substitute a small L-match antenna coupler and short counterpoise. As its not supporting anything, the antenna wire can be the lightest grade of insulated hook-up wire. This lightness allows it to be supported on a telescopic squid pole - a huge advantage near the beach without trees.

An end-fed wire of approximately 20 - 22 metres long and a 9 metre pole provides good local and medium distance results on 7 MHz. Because of the coupler it provides multiband capability. It will tune on 14 MHz as a 1 wavelength end-fed but doesn't seem to be as good as a vertical dipole for DX. 
Alternatives include forming it into a full wavelength loop on 14 MHz, or using the same loop split at the top as a bi square on 28 MHz. The end-fed inverted vee is highly recommended for local and medium distance portable work on 7 MHz and usable on other frequencies as well.

Generally the antenna should be mounted as high as possible. In most areas, it should be possible to find a suitable tree to support an antenna, though there are cases when it would be wise to bring a collapsible mast, for instance in the mulga or at the beach where there's few tall trees. Telescopic squid poles have been particularly successful up to heights of 9 or more metres. They will work with end-fed wire antennas if the thinnest type of plastic insulated wire is used to minimise pole bending. 

A 9 metre pole can easily support a span of 20 metres; adequate for 7 MHz and up. Light duty squid poles won't normally support even RG58 coax feedline unless it's run down the pole and taped to it every metre or two for support. Squid poles are too flimsy to support a VHF beam but they'll work with a lightweight antenna such as the 'hanging dipole' elsewhere on this site provided the feedline is taped to the pole. These poles have revolutionised amateur portable operation due to their low cost (under $50) and light weight. A suggested supplier in Australia is Haverford who ship nation-wide.

There are other antennas suitable for portable usage (such as the loop pictured above) but those described are the simplest and most foolproof. More elaborate antennas are not needed unless space is extremely limited or gain is needed for DXing.

This article originally appeared on my website, vk3ye.com.

PS: Into low power amateur radio? Minimum QRP is the top-selling manual on the equipment, antennas, operating and strategy of successful QRP operating. It's available for under $US 5 each in electronic form. Or you can get a paperback version. Visit VK3YE Radio Books to find out more. 

No comments:

Post a Comment

Upgraded vk3ye.com website

Enjoy reading about diverse facets of amateur radio? Like building projects? Sometimes find my videos hard to find? If any of these applies ...