Wireless Antennas used during WW1

[RockingHorse]

Hi, does anybody know what types of antenna were used with the Marconi wagon and pack wireless sets used during World War I? These big, impressive sets were each issued with two masts, which would suggest the antenna wire was strung horizontally between the two - i.e. full skywave dipole. However the early experiments by Marconi around 1900-1910, including sending Morse Code messages across the Atlantic, all seemed to use vertical radiators - very high ones. The sources also mention antennas being mounted on chimneys and flag poles, which again suggests vertical radiators.

It's a real puzzle, as vertical antennas radiate groundwave, whilst horizontal ones radiate skywards and then bounce the signals off the ionosphere. The latter would be used today for long distance radio communication in the HF band, but whether they could possibly have been used for primitive spark gap wireless is a mystery to me. If the latter type were used as early as World War I that would be extremely interesting. Any information would be gratefully received!

[WhiteStarLine]

@RockingHorse I don't know myself but I can perhaps point you to some references that may help.  Apologies if you have already downloaded "The Signal Service in the European War of 1914-1918 (France)"  Work of the Royal Engineers in the European War, 1914-19.  BY R. E. PRIESTLEY, M.C, B.A. (Late Major, R.E.). 

There are 5 references to Marconi and many on wireless.  This is one and there are others on the Marconi pack set: 

Meanwhile, intelligence wireless was daily gaining ground and in October was reinforced by the arrival of the first wireless "compass" station in France.* This set was designed to give the accurate direction of any enemy station whose working it intercepted. The use of the device is obvious. If two or more bearings could be obtained on any enemy station within reasonable distance, the position of the latter could be accurately plotted. 

* The set was a Bellini Tosi pattern modified by the Marconi Company. Its outstanding features were the exceedingly sensitive valve receiver, a specially designed directional aerial, and revolving inductance by means of which the strength of the signals received from the distant station could be varied. 

[awjdthumper]

14 hours ago, RockingHorse said:

Hi, does anybody know what types of antenna were used with the Marconi wagon and pack wireless sets used during World War I? These big, impressive sets were each issued with two masts, which would suggest the antenna wire was strung horizontally between the two - i.e. full skywave dipole. However the early experiments by Marconi around 1900-1910, including sending Morse Code messages across the Atlantic, all seemed to use vertical radiators - very high ones. The sources also mention antennas being mounted on chimneys and flag poles, which again suggests vertical radiators.

It's a real puzzle, as vertical antennas radiate groundwave, whilst horizontal ones radiate skywards and then bounce the signals off the ionosphere. The latter would be used today for long distance radio communication in the HF band, but whether they could possibly have been used for primitive spark gap wireless is a mystery to me. If the latter type were used as early as World War I that would be extremely interesting. Any information would be gratefully received!

You have to bear in mind that during WW1 radio transmission was only operated over modest ranges of a few miles between different strata of each army corp. This did not need the use of a ground wave nor use the use of the Ionosphere!

The biggest danger for radio transmitters was detection by the enemy and therefore using aerials mounted high off the ground was normally avoided. The Marconi Pack mentioned used a 525' wire strung between two 70' steel masts. For lower powered transmitters, a similar arrangement was used of smaller size mounted closer to the ground which reduced the transmitter range.

The other thing you have to bear in mind was that the aerials used were very low gain or directivity producing a doughnut shaped pattern. A vertical dipole might have been better for transmitting horizontally but the horizontal dipole worked pretty well although needing to be aligned roughly with the direction of the receivers (eg within about 45 degs in azimuth). 

[Chasemuseum]

Hi RH

While mostly agreeing with thumper, I disagree with the description of the 500W pack set antenna. It was an end fed horizontal wire 120m long. It was actually two parallel wires about a metre apart. The masts were interlocking steel tubes 9m tall. An “earth mat” was laid on the ground between the masts.

Both the 500W pack set and the 1500W wagon set were adopted in 1913 and continued in service through the war although with various updates. They were used on the Western Front during the initial period of movement but really lacked purpose during trench warfare. They were much more widely used on the other fronts such as Gallipoli, German East Africa, Palestine and Mesopotamia.

Wireless took an entirely different turn on the Western Front, with many models of spark and continuous wave machines developed, the introduction of hard valve amplifiers and ground transmission with the power buzzer.

The 500W pack set was to be deployed with the Cavalry Brigade to communicate with Divisional HQ, with two stations so that they could leap-frog and maintain constant communication in the field. In practice a well-trained signal troop could fully deploy a station in 5 minutes. The station nominally had a range of 35 to 40km. The Australian Government purchased six stations which were delivered in very early 1914. The first transmission was from the “Broadmeadows” training camp, to Army HQ at Victoria Barracks, Melbourne, about 18km. Experiments with the stations during 1914 found that much greater ranges could be achieved at night. These stations were deployed at Cape Helles during the Gallipoli campaign as the only portable wireless available in theatre. They communicated to the fleet co-ordinating naval gun fire.

 

The 1,500W wagon set were to provide mobile communication from Division to Corps to Army HQ. In many ways they were similar to the pack set, the crystal receiver was near identical. It was arranged as a “limbered wagon” format. That is two 2-wheel horse drawn vehicles. The front vehicle being the limber, where the team of horses is attached through draft harness and traces and the rear vehicle as the wagon, with a drawbar and ring attached to a tow hook on the back of the limber. A station is three limber wagon vehicles. The technical unit is a petrol engine generator in the limber and the wireless equipment in the wagon. The other two are the mast units, each a cargo limber and telescopic mast wagon.

The antenna is similar to the 500W pack set excepting that the two-end fed horizontal wires are 170m long and the masts are 20m tall.  (approx. 560ft and 65ft).  

Technical unit, wireless wagon with the generator limber in-front

 

 

The mast wagon, erecting the mast. Once in place and suitably guyed, the wagon could be detached an removed.

Cheers

Ross

 

 

 

[Jeff Pickerd]

A search of the Australian War Memorial, using the search ‘Marconi wireless’ brings up one photograph with the following description, “Prospect, NSW. 25 October 1913. Group portrait of militia around Marconi wireless station 12 W.S.D. at Field Station A, Camp Prospect.” (PO2952.001).

Here the Marconi Pack set, with single mast is depicted. The AWM site also has four photographs of the two wireless stations set up on the beach at Anzac Cove, morning of the 25th April, again depicting single masts.

The 1913 Militia photo clearly indicates that the Australian Military forces had the Marconi wireless 500W Pack sets prior to the formation of the A.I.F. Thursday 13th August 1914, although, how many sets at that stage is not known to me.

Jeff

[awjdthumper]

3 hours ago, Chasemuseum said:

While mostly agreeing with thumper, I disagree with the description of the 500W pack set antenna. It was an end fed horizontal wire 120m long. It was actually two parallel wires about a metre apart. The masts were interlocking steel tubes 9m tall. An “earth mat” was laid on the ground between the masts.

My comments were in connection with the 1.5 kW Pack radio rather than the 500 W one.  These types of LF/HF aerial need a ground plane and on the Western Front, the generally wet earth would have served this purpose although in arid parts of the world a metallic 'Earth Mat' would have been required. Using two wires 1 m apart would have served no purpose from an electrical point of view and would have generated the same directivity pattern as a single wire. I assume the second wire must have been used as a spare.

[Chasemuseum]

9 hours ago, Jeff Pickerd said:

The 1913 Militia photo clearly indicates that the Australian Military forces had the Marconi wireless 500W Pack sets prior to the formation of the A.I.F. Thursday 13th August 1914, although, how many sets at that stage is not known to me.

There are lots of photos of the pack sets and their antenna on the AWM site. I have found over 50 and as many again of other wireless types and antenna configurations.  With the masts 120m apart, many photos only show the mast near the transmitter. There have been several articles on early military wireless in Australia published in Amateur wireless magazines and material in several books including some of Peter Jenson's works. The source of a lot of information was interviews with Bert Billings, who was with the militia wireless troop before WW1, then at Gallipoli with the troop and continued the war with a Light Horse wireless troop in Palestine before transferring to the Australian Flying Corps. A good article is "Amateur Radio, April 1990 "The Last Wireless Anzac" by Jim Linton VK3PC. Mr Billings was still alive at the time of publication but in very poor health. From one of the various articles, there were 6 pack sets delivered early in 1914 but no information on how they were distributed around the country. In the AWM photos there are prewar photos of them at Broadmeadows Camp north of Melbourne (now inside greater Melbourne) and near the Barrenjoey Lighthouse on the south entrance to Broken Bay. (A training exercise, as far as I know, there has never been an army base or training ground there, although there may have been look-out stations maintained there during the two wars.

 

Cheers

Ross

[Chasemuseum]

12 hours ago, awjdthumper said:

My comments were in connection with the 1.5 kW Pack radio rather than the 500 W one.  These types of LF/HF aerial need a ground plane and on the Western Front, the generally wet earth would have served this purpose although in arid parts of the world a metallic 'Earth Mat' would have been required. Using two wires 1 m apart would have served no purpose from an electrical point of view and would have generated the same directivity pattern as a single wire. I assume the second wire must have been used as a spare.

This is a period of early field wireless. Antenna propagation theory was still in its infancy. I think you are giving more credit for an understanding than is appropriate.

[Chasemuseum]

Some of the AWM photos

A pre-war photo of the 500W pack set at Broadmeadows (Melbourne) (AWM DAX1057)

Carrying the pack set up Barenjoey (Sydney) (AWM A00121)

 

Detail of antenna mast at Romani, Palestine (AWM J06539)

 

 

 

[RockingHorse]

Thank you so much everybody for your expert comments. If I understand correctly, several types of antenna configuration must have been used (which makes perfect sense), but horizontally strung wire between two masts, albeit at close to ground level,  was indeed one of these configurations. But we can probably conclude that the intention was not to use the ionosphere to communicate long distance. 

This puzzle began for me when I found a reference in the War Diary of the 1st ANZAC Wireless Signal Squadron in Mesopotamia. It read:

2/11/18 No 5 Station dismantled at 15.20 in order to change direction of wagon aerial from east and west to north and south, to escape land line induction.

This reference ruled out a vertical radiator. It didn't rule out a sloping wire or a droopy dipole configuration, however neither of these requires two masts. So if two masts were used and the antenna was directional according to a compass bearing, the arrangement could only have been a full skywave dipole strung horizontally between the two masts.

But maybe a dipole is not necessarily a 'full skywave dipole'. I think that's where I'm being misled by the modern terminology for these types of set-up.

[Chasemuseum]

AWM J01972,  1st AWSS erecting the antenna for the 1500W station in Mesopotamia Both masts are visible, and have been erected and guyed. They are about to start hauling up the antenna wires. Totally agree with thumper that using two wires would have had no benefit over the single wire, but this is a station designed on 1912/1913 understanding of propagation.

Thornycroft steam truck being used as a mobile wireless station in an experiment by the Marconi Company. A rather interesting antenna configuration.

Royal Corps of Signals 1932 Morris "Gin Palace"

 

 

[Chasemuseum]

The following is from a booklet produced with the endorsement of the Marconi Company during WW1.

 

 

 

 

Cheers

Ross

 

 

[RockingHorse]

Thank you Chasemuseum, for these superb photographs and a very interesting technical manual. All totally new to me. I really appreciate your help!