Phased verticals for portable operation When working on portable or in DX- peditions the key concern is how to maximize antenna performance per kilo of weight of the antenna to be carried to the distant location. Antennas also have to be easy to install and all the adjustments have to be fast and straightforward. One antenna that accomplishes very well those criteria is the array of phased verticals. What follows is a description of the well proven array of two verticals for 40 meter that we have used in IOTA contests with great results. Total weight is less than 7 kilograms and it can be easily carried in a backpack and you still have spare space left for the rest of equipment. Performance is in line with that of a two elements yagi for 40 meters placed at 20 meters high. The following implementation was developed thanks to the skills of Duncan, EA5ON. The two verticals are identical and made of copper wire supported on a fiberglass rod. Spiderbeam manufactures a very interesting 12 meter fiber telescopic pole that is perfect for these antennas. The vertical radiator consists on 10.4 meters long wire that can be placed over the pole with 3M tape or fast plastic grips, starting at a height of 1.5 meters. Each vertical has two elevated radials that will start at the 1.5 meter high feed-point of the poles and will run paralel to the ground or with a slight slope. The length of each radial is also 10.4 meters. Separation among the two poles determines the shape of the lobe of radiation of the antena. A good F/B and a convenient lobe are achieved with a separation of 11 meters. The resulting lobe is wide enough for contest, where you want your signals to be spread on ample areas of interest with good gain. It is extremely important to place this antena very close to the seawater to get the most of its potential performance. The low angles of radiation and forward gain are very dependent on the reflection on the surrounding “ground”. The pseudo-Brewster angle for vertical polarized signals is only low when the conductivity of the “ground” is high and on this aspect, the best “ground”  is seawater. The phasing of the two verticals is performed with a 270º long line of coaxial cable. You have to be cautious when using transmission lines as phasing devices as they only work well when impedances are closely matched but on this case it is well proven that they work very well. When using RG213 coax cable with a velocity factor of 0.66 the total lenght is 20.8 meters. A couple of antenna switches can be used to change the direction of the antenna. On air results of this antenna were amazing. When running just 100 watts from EU-093 at EE5KB, the pile-ups of JA stations on 40m were memorable. EE5KB from Tabarca Island EU093 (photo EA5FL) Azimut plot at 13 degrees of elevation EE5KB from Tabarca Island EU093 (photo EA5FL) Home        Shack       Antennas       Maritime Mobile       Propagation        Gallery          QSL info