Equipment for portable HF operations
The Sun is shining and you want to work outdoor, in the field, in portable HF operations. But how to move there your ham shack and antennas ? It is an impossible task. It is a scenario that most of us have experimented one or another day. Like most of us you will be quickly confronted to practical concerns, and you will rapidly conclude that you are unable to move your huge beam or vertical and sometimes your heavy and large high-end transceiver and its companion, the amplifier. So you will have to bring with you a lighter installation, easy to move and to set in the field.
We will mainly focus our attention on the antenna. Transceivers come in many models and in their portable version it is really not a problem to install it below the car radio, on the dashboard or close to the glove compartement. The antenna system is another affair as it becomes quickly huge when we desire to work in the HF bands, for example in the 40 or 20-m band.
The location and means
Before installing your equipment somewhere in the field you must answer to several questions. First, the location : in what car or place do you want to install your material, not only the transceiver and its power supply but first of all the antenna and its supporting mast ?
We will not discuss about the shack installed in a second QTH (/A) where you can have a replica of your home installation, but only about true portable installations (/P), including mobile (/M) working standalone in the field, and not remotely controlled over Internet (maybe in a next article).
Depending on your needs there are several solutions, from the Hummer, the monospace or the caravan fully equipped to the compact car that you usually drive that will temporary receive your portable installation.
The first solution can be assimilated to a mobile ham shack equipped with permanent rigs or rigs that you rarely moved. This is a typical "california style county expedition", HI!
The second solution is probably the most used, most amateurs going in the field with their usual car or pick-up for a few hours during the weekend or by a sunny day. Others apply this method to a "sport and nature" solution, I mean climbing on top of a mountain to active a peak, to name for example the "Colorado 14er Event" or have the opportunity to work in large open fields like Olafur, TF3ML in Iceland, where he can easily erect a tower mounted on a trailer.
When radio amateurs meet adventure and sport
Hopefully, not everybody is obliged to buy a Hummer, a mobile tower or to be fan of trekking to practice a portable activity ! It is fine if you like adventure or sport but in the field, most of us don't have a national park or high summits in their neighborhood,. So let's leave these solutions to lucky hams living close to a natural park or large ranges. CQP and other heavy loaded DX-peditions deserve our attention but they are exceptions.
In usual circumstances, we have to take into account that our transceiver and accessories have to be compact and the antenna either telescopic or easy to dismantle to fit in a car or on the roof once the activity ended. For sure, if you own a trailer the transportation will be still easier.
If you consider moving abroad by plane and take profit of this trip to work on the air, the selection can extend to other constraints (weight, portability, etc). This solution will request some comments specially about antennas.
As we just told, the question of finding a small and light transceiver is not a problem, most manufacturers offering a large range of mobile transceivers very suited to that usage and with powers ranging from QRP to 200 W, dedicated to HF or multi-bands.
Even a mid range transceiver like the Kenwood TS-570D series can be installed in a car, as shows the picture below left. Of course its size (27x10x27 cm) and its weight (6.8 kg) are at the limit of portability but it is anyway 2 to 4 times lighter and almost 40% smaller than a desktop high-end transceiver (14 kg and 40 cm wide for Yaesu FT-1000MP, 23 kg and 43 cm wide for Icom IC-7851) !
A Kenwood TS-480 control panel in the French Alps linked to its base installed in NY
Whether you use a small desktop transceiver or a mobile model, you will need additional cables from the battery to power the transceiver and the possible accessories. Depending on the tansceiver, wires can arrive discretly below the glove compartment or be gathered underneath the driver seat.
Engine shut down and working only on the car battery, such an installation support without problem 100 W PEP during a few hours. Of course an independent battery will be more secure. We will come back in the last page about the power supply.
If modern mobile transceivers like Icom IC-706MKIIG or Kenwood TS-480HX are true performers for their size and price, offering many functions including memories and filters, their only drawback is that most functions are accessible using a combination of keys, their small size doesn't allowing to add many controls on the front panel.
Note that the small IC-7000 released in 2006 and displayed below right was the first mobile transceiver using a color TFT screen. This "mini IC-756 PRO111" comes with several filtering capabilities, memories and scan options, and already counts among the best products.
Only minus point, during RX operations, the cooling fan of this mobile doesn't work. Consequently the rig gets quite hot in operation and as the mean time between failure also depends on the heat (MTBF decreases of 50% each time that the temperature increases of 10°C), it is a problem that Icom has to fix. We will not extend more longer on this selection.
To use in the field using a WiFi or cell phone:
Finding a portable but sturdy mast
Let temporary aside the question of the antenna on which we will extend on the next pages. The next question concerns the antenna mast. This question interests mainly amateurs working with short HF or VHF beams that are sold without mast. Verticals are stand-alone, and are usually sold with a small tubing fixed parallel to the main tube while wire antennas (dipoles, etc) request only one or two poles a few meters long (or an anchor in elevation if the dipole is installed in inverted V). A tree, a wall, a chimney or even a fishing stick is ordinary used.
Factors to consider in selecting a mast are first the weight and windload of your antenna, then its height in operation and easiness to set up. To work in HF, for security reasons and to respect manufacturer standards, select preferably a robust mast which top element, the one connected to the boom, has a diameter close to 50 mm (2"). That means that the base element placed at ground level has to display a larger size, of about 70 mm. Of course to support a dipole weakly wired 5m up, the mast can be lighter.
To reach a height of 8 to 12 m (40'), these masts are usually telescopic, made of several individual sections, from 1.2 m (4') to 2.4 m (8') long each, to push-up manually, with a winch or electrically.
The small telescopic mast (poles), made of aluminium or fiberglass are manual, their weight is ranging between 1-15 kg, and cost up to some hundreds euros. The smallest are cheap but can only support very light antennas also. That means that at the first gust wind, your mast could bend or even break. Check carefully specifications before buying.
Among these monopoles and light telescopic masts, name models sold by WiMo and UKW-Berichte (eshop at Stecker-shop) in Germany. Name also The Mast Company (Tmasco) and MGS in the U.S.A. These companies sell telescopic masts which segments have to be taken out or pushed up manually.
Name also heavier masts manufactured by Force12 (now JK Antennas) and The Mast Company in the U.S.A among others. Due to their weight, their exportation could increase their price from 50 to 75% (10 kg imported from the U.S.A. to Europe costs between 150-200 € +VAT and taxes).
You can also find sturdy masts to companies specialized in military and scientific equipments like Comrod in Norway and Clark Masts in United Kingdom. They sell masts for all applications, manual (using a winch or a small motor) or pneumatic, in aluminum and sometimes in composite and light material. Most models can be erected at ground level, on top or at rear of a car or a van. The price is relatively high but you have the warranty to use quality material that will not fail to support your beam under gusty wind.
At last, forget pylons (towers) to work in the field. It is without saying that due to their weight and difficulties that requires their installation (large steel tripods, fork-lift truck, etc) they are dedicated to expeditions and Field Days à la N6RC or to permanent installations.
If you are interested in short HF beams for portable operations, working alone or with friends, some "shortened" antenna models can be relatively light - their weight is usually less than 10 kg - but most of these beams present some drawbacks (wingspan, fragility, etc). Until recently the weight of the "smallest" beam was close to 20 kg and requested the heaviest mast or better, a pylon to support it due the weigth of the structure made of stainless steel and thick aluminium (over 2 mm thick, tubing dia. 50 mm).
If you want to load a classic 3-element beam on top of a mast as we see a lot during Field Days, you must secure the mast with flexible or rigid guys to prevent any accident. But to support a full length beam for the 20m band for example or even a small Titanex, knowing that their weight is ranging between 8-15 kg, you need a stronger structure; either a small pneumatic mast or a sturdy telescopic model, if possible equipped with a winch, able to support a rotator and a winload of about 50 kg at 100 km/h
You can also buy a lighter pylon. For example a small aluminium or fiberglass mast made of 4 or 5 elements 2m long each, and 50 mm wide at the base. Attached to guy wires it is able to support a 3-element multi-band beam. Avoid the stainless steel mast as the overall weigth of the mast can exceed 100 kg. In most cases, a van or a trailer will be probably necessary to transport all this material. To reserve to group activities.
Most HF beams display a wingspan (the length of the larger element) close to 5 m at best, usually closer to 10 m long (for the 20 m band and lower). In worse cases, so-called "portable" models (because they are light) are really cumbersome with booms measuring up to 10m long (e.g. the DF4SA's "spider beam" as well as several wire beams). Their advantage is their featherweight (DF4SA is 5 kg, Hex-beam is 3 kg).
However some beams are made of titanium - known for its resistance and lightness - or are made of light aluminium tubing (1-2 mm thick), that might be supported by ordinary telescopic masts. Some models like the ASM 70 mast from UKW-Berichte in Germany costs about 180 € Inbus-wrench and screws included. Such masts extend up to 10 m high, with elements 2 m long, just small enough to fit in your car. The ASM 70 mast offers a diameter from 70 to 45 mm. Its weight is 12 kg. Models sold by Tonna are best suited to support V/UHF antennas.
However, underline that using a beam for portable operations, even a small one, is somewhere an absurdity. Indeed, most low to mid-range beams, even shortened, are usually made of stainless steel (inox) and aluminium, and very few are light, made of titanium or fiberglass.
So, even if they can be very well assembled with quality U-bolt, hex nut and other worm clamps, most of them are heavy, cumbersome, and they will not support long times to be dismantled and remounted again and again. Worse, how will you set up an antenna exceeding 15 kg on top of a mast that weights as much ? It is already difficult to erect alone a 7 kg vertical 8 m long, so you will surely get in trouble in trying to erect alone a beam of 15 kg over a few meters high.
Think also about issues you already sometimes encounter to carry alone an aluminium ladder 8 m long which weight is about 12-15 kg. Sometimes you are at the limit of your capabilities to erect or to move it. The same for a beam. But you can succeed with one or two friends and some great accessories like a pulley or a winch.
If you work alone in the field you should have at best to dismantle elements from the boom and disjoin each element with the hope to put all them in your van, on your car hardtop or in your trailer. But do not imagine to handle elements longer than 4 meters... Worse, if long spreaders or X-hat 1 meter long are attached to these elements the situation is at risk, if not impossible to manage.
Without more convictions, forget also HF quads and similar models for portable operations, excepted if you work on the 10m band where their size is relatively small (about 2 m wide), or if want to set them up on top of a pylon with friends to celebrate a special event, during a Field Day, a JOTA, a castel expedition or an open-door.
Remember that quads are usually very cumbersome, each side of the frame measuring about 5 m long for the 20m band with a boom exceeding 2.5 m long for a 2-element quad, without to forget that they are made of wires tight and fixed all around the frame ! There is few chance that you find "short" quads to work on HF, excepted Degen's BBQ (see page 3). And no more chance to place it in your car once assembled !
Then, the initial assembly can last 6 hours or more and once set up it can be hard to dismantle the quad. At last it is quasi impossible to install a 15 kg quad at 10 m high manually, without assistance (some friends or using a pneumatic system), and you need a robust mast to maintain it in windy locations or if you want to use it with a rotator.
This is thus a very difficult task without equipment to not underestimate. So I suggest you to reserve quads and other beams for permanent or long-duration installations, and group activities.
So due to all these limitations, usually amateurs working in the field use the lightest antennas available, shortened verticals, dipoles and other OCF Windom fixed in trees or on light poles. Nowadays however they are some light beams, mini quad and poles made of titanium suited for portable operations that amateurs do not hesitate to install for Field Days contests or to work alone away from RFI.
Radiation : warning
You have also to take care about the impact of electromagnetic radiations on health. In many mobile installations, the antenna radiator is placed 1 m away only from the operator, sometimes closer. Sending 100 W PEP in this antenna, the electric field strength can exceed 150 V/m. At long term there is a risk that you contract a cancer, even if no case have been observed yet. So, a good advice, knowing that the strength of both electric and magnetic fields drops of 4 times each time the distance double, it is recommended to install your antenna over 5 m away from your operation position, where the E-field is reduced to less than 10 V/m.
Finding a performing antenna
Working in the field or on a parking if the weather permits requests some compromises. As you cannot use your largest permanently fixed antenna system in the field due to its weight and its wingspan, definitely do not expect that your portable system, usually of shorter size, will display the same performances as your fixed installation... You should have to fall back on challengers that display lower figures. Hopefully some portable antennas are true performers.
The last and main problem is of course the choice of the antenna and its support. All begin by reading advertisings and reviews in magazines or on the Internet, then visiting a hamfest or a near dealer well-stocked.
Many manufacturers speak highly of performance of small and light antennas suited for mobile or portable operations. But looking closer most of them look more like simple CB whips a few meters high than to true HF antennas; their largest stick displays giant coils 50 cm long showing a low unload Q, no ground system, no radial or capacitance hat to improve their performances. These mobile antennas offer usually a poor Q-factor (Q of the antenna system) not higher than 60 where the best mobile exceed 500. Of course any good antenna has a price, rarely cheap.
Then, if most manufacturers of directional antennas give the Front-to-Back (F/B) and Front-to-Side (F/S) ratios, some give only the second value to increase their figures. Others give the antenna gain measured in optimal conditions, e.g. 20 m high for the 20m band, a height that not everybody can reach. But we all (should) know that at less than half that height (8 m) the gain drops up to 30%. In fact, no many manufacturers state at what height their figures were measured... All this lacks of transparency.
At last, some manufacturers try to convince radio amateurs that a versatile dipole using rotary arms can be converted in a sort of delta loop or so. But before buying an antenna, re-read how work the different antenna designs, their advantages and drawbacks, and know what you buy to avoid bad surprises once in emission ! In this context, nothing is worth a direct or email contact with the manufacturer or be allowed to test the antenna before purchasing it.
Do not forget also that if a trap can reduce the physical length of an antenna up to 20%, it attenuates also RF signals between 0.5 and 1.5 dB depending on the frequency. That means that in worse cases, in using a "shortened" vertical equipped with 2 traps, your signal looses 1 dB or 25% of its power ! This will thus affect your coverage. Your antenna being shortened, you pick up efficiency will be also reduced compared to a full length model.
At last any vertical shorter than 1/2λ, and whatever say some advertisings, needs radials or at least a ground to work against, and the better the ground the better performances.
If that exists, a "good" antenna, I mean an antenna able to work any pileup and DX station, due to mysterious marketing reasons, is expensive, usually over $500 or 700 €, and for such a price it is better to make the good choice...
"I did it !" will say some amateurs who do not want investing in their antenna system but rather in the time they spend in working in CW, improving their speed. We have to respect their choice but not everybody like working in Morse code or in digital mode.
With the hope to work in the field, far from local QRM and other sources of man-made RFI, I have tried to find a performing antenna system that should meet the next specifications :
- By design it has to be multi-bands, mainly for DXing and, if possible, to be heard from pileup operators
- The antenna system has to be small to be carried in a mid-range car (parts no longer than about 2 m)
- Parts of the antenna and its accessories have to be as easy to set up as possible (in less than 1 hour)
- The antenna system must be light enough to be transportable (less than about 15 kg)
- Versatile in that sense that I hope to use it at home too, installed on the roof top or in the garden
- The antenna boom (if this is a beam) must be compatible with a mast diameter smaller than 50 mm
- The antenna must be an excellent performer vs its competitors
- Its price should be below $500 or 700 € (a very subjective matter and hard to meet excepted building it yourself).
First of all, whatever tell advertisings, you must know that in HF bands any stick works fine from 20 to 10 m. Not necessary for DXing but if you like ragchewing and work local QSOs or near stations, most portable or mobile sticks 1.2 m long (e.g. Comet models) can do a great job.
To reach DX or work pileups is another affair ! If you want to reach the farest DX with a good signal (say over S-5) there is no secret : you need excellent working conditions. That means either a performing antenna system, or excellent propagation conditions, or you must work in CW, or you know habits of your DXer, or at last you are lucky and you meet all these requirements, Hi ! But usually, not everybody is so lucky and most of us have to beat against pileups to work DXers or to get one more point at our DXCC palmares.
Selecting an antenna from advertisings is a mistake. Indeed, as we just explained, manufacturers tell what they will in their advertisings. Some optimize figures of the radiation efficiency for the 10m band, others, more objective give the value for a mid-band supported by their system. Some display radiation patterns for an antenna placed 20m high, others in free space. Some give the Q-factor of the coil in place of the antenna system. At last, very few manufacturers display the VSWR all through the band although we know that at the limit of each band it can easily be 2 or 3 times higher.
All these factors combined can disappoint potential buyers who can no more compare models among brands. At the end, after have paid the invoice, the amateur can be deceived by the antenna he bought, the attracting publicity being far to be conform to the results in the field.
The problem is similar with beams and more original concepts. Due to the design, some loops are hard to distinguish from a variant of dipoles and thus amateurs have difficulties to compare their performances with antennas of the same family. Therefore some amateurs suspect these manufacturers to sell disguised "dipoles" as delta loops or Moxon-like... Hopefully true loops display a gain much higher than the one of simple dipoles and quads cannot be surpassed (say at least 7 dBd at 8m high for a 2-element quad, similar to the one of a 3-element beam).
So we can only compare what manufacturers accept to tell us or we have to wait that a staff of experimented and independent testers made measurements in the field like did Fritz Markert, DM2BLE, or simulating properties of this antenna in a modeling software like EZNEC or in near-real conditions with MultiProp. For new models these reviews can keep waiting several months or even years. In the meantime, amateurs have to decide by themselves in comparing models approaching these specs or questionning advanced users. For novices this is not an easy task. In the best case, personal websites and radio clubs can help you in providing reviews or sheets comparing various antenna models. As a last resort radio amateur forums are your ultimate source of information. Two of them are very popular : rec.radio.amateur.antenna and eham.net among many others.
At last, the best advice that I could give you is to always read reviews of material *before* buying and to well read technical specifications. In case of doubt do not hesitate to question the manufacturer.
To read : To buy or not to buy from overseas ?
Shipping, taxes and troubles...
A last word if you order hardware overseas. Know that in average the delivery time exceeds one month. Ordering from a bordering country, sometimes the delay can be reduced to 2 or 3 weeks. If you wish to buy your antenna from overseas, the delay can reach 2 or 3 months. So, I suggest you to buy only manual antennas without electronics or mobile parts, source of potential problems and thus, servicing. All antennas list in next pages meet this criterion.
At last, you can also buy your equipment at an hamfest like Dayton (USA), Frederikshaven (Germany) or La Louvière (Belgium). Usually their price are far lower than the street price (a discount up to 40% is not unusual) and you can benefit of an extended guarantee, sometimes international. Don't hesitate to take advantage of this opportunity !
Let's see now our selection of portable antennas.