DG7YBN / 432 MHz / GTV 70-11w
  Last Update Sept. 2th 2018


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Super Moonbounce Array by DL7APV
128 x GTV 70-11w

One of the largest ever built 70 cm band arrays. Area: 18.0 x 8.7 m or 636 x 285 ft.
128 Yagi-Uda GTV Antennas with Folded Dipole at a length of 2.81 λ phased by Open Feed Lines








Pattern in 3D Pattern, 4nec2's 3d viewer

Pattern in Cartesian Coordinates, 4nec2 & Gnuplot

Azimuth - real Array measured by DL7APV -17 ... 17 deg. - on Courtesy of DL7APV (tnx!)

Elevation - real Array measured by DL7APV -17 ... 17 deg. - on Courtesy of DL7APV (tnx!)


Overall Data

Specs: with 4 mm elements @ 432.1 MHz

		Gain approx.            36 dBi
		Antenna G/T             20 dB (Tearth 458 K, Tsky 27 K)
		-3 dB E-plane       less 2 deg.
		-3 dB H-plane    approx. 4 deg.

		Size of Antenna Field
		Width                 18.0 m 
		Height                 8.7 m

Systems RXing ability

		Sun Noise             21.6 dB at an sfi < 30 at 432 MHz
		Sagittarius A          7.3 dB
		Cassiopeia A           5.3 dB
		260 W EIRP EME signal  -25 dB in WSJT
		Pulsar B0329+54 easy detect within 200 sec sampling time

Own Echos

Detection of own Echos
     from               100 mW in WSJT
			200 mW using CW


		Relay:               HF2000 with DIN 7/16
		LNA:                 DJ3FI Cavity-Preamp plus 2nd stage
		NF:                  0.35 dB, Gain 42 dB

Bill of Materials

			Booms alone           384 m of 20 x 20 x 2 mm
			Weight                150 kg
			Elements              390 m of 4 mm aluminum rod
			Open Feed Lines       224 m of Cu-wire 4 mm
			Concrete Basement     10 tons
			Steel       approx. 2400 kg of construction tubes and bearings 

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The Making of the Array

The builder himself: Bernd, DL7APV


and his Site Supervisor


• 2008

It seems the starting point of this crazy scale project was when Bernd could get his hands on a pivot mount of a good size backhoe digger. Which with a diameter of 1.6 m and weighing 500 kg has just the right dimensions. In his presentation at the 2018 EME Conference he describes the buy as a "happy accident". Quite right Bernd!

• 2009

The foundation groundworks are taking place. His neighbors help with digger and lorry. The hole eats up 10 tons of concrete.

• 2010

The mighty pivots gearbox is overhauled and the horizontal lattice beam is made

• 2011

This year sees Bernd mounting the pivot to the foundation and erect the support construction taking the mid section of the horizontal lattice beam into a height of 5.5 m.

• 2012

Azimuth and elevation rotators are engineered, build and mounted. The outriggers to the horizontal lattice beam are mounted. After that the project seemed on halt as he mounted an array of 8 FM Yagis on the carrier only.

• 2015

However in this year Bernd was going strong again. Time to make a choice which antennas to engage for the job of 432 MHz EME. Focusing on Low Antenna Temperature, clean pattern and not critical VSWR when wet he picked the DG7YBN GTV 70-11w for a pretest.

• 2016

Bernd builds a 4 bay of GTV 70-11w with Open Feed Line and performs detailed testing to verify gain and pattern. He also mounts the 24 vertical carrier tubes to attach the 128 rear mounted Yagis to.

• 2017

Into mass production of the 128 Yagis now: 1792 holes for taking the elements, 1280 elements to be cut precisely, 2560 insulators to be pushed in (the first charge of 7arrays 4x6 mm insulators went into this project). 128 bent dipoles to be made from copper rod. Plus many a meter of open feed line. The first Yagis are being mounted.

• 2018

The feed lines are being completed and by April the array is ready for first tests. Which show a VSWR of 1:1.3 without any tuning and a sun noise of 20 dB straight away.

More details see DL7APV website






73, Hartmut, DG7YBN

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