arecibo 2.0

jan2021

links
equipment
challenges
visibility (elevation range) from inside the current sink hole
papers to read

Equipment

Transmitter

Solid state amplifiers vendors for Tx

amplifier configurations

freqRange	company/model	power/type	PAE%	# for 25KW/1MW	PowerNeeded For1MW	Notes	dataSheet
2-6 GHz	qorvo spatium amp	400W/cw	40-28%	64/2500	2.9MW	Just amp	.pdf
2-6 GHz	polarity/p400w2-6cp 1 qorvo amp	400W/cw	""	64/2500		Looks like they've packaged 1 qorvo amp in a system.	.pdf
2.8-3.5GHz	empower/model 2236	24KW/cw	25%	1/40	4MW(KVA)	system, 2 19"Racks	.pdf
150-450Mhz	empower/model2210	12KW/pulse		2/84	672(KVA)	system,19RU(32") 390Lbs,forcedAir PulseW:.002-2ms dutyc:2-20% Droop:.7-1db pwrinp:8kva	.pdf
400-450Mhz	empower/model2234	180K/pulse		1/5.5	550(KVA)	system,2x19Racks pulseW:.2-500usec dutyC:.5-10% liquidcool:25psi,85gpm 400 15mTel->72MWPk	.pdf

Challenges

Transmitters

power will have to be passed to the horn via waveguide

waveguide is narrow band, so you'll have to have a separate waveguide run for each freq used
This requires a mechanical switching network at the power amplifier and the horn to select the tx frequency. One of these for each antenna.

Plate (to get rid of shadowing)

a 1000' plate going to 45deg

sin(45)=.707

vertical range plate at 45deg is 707feet
center of plate 707/2=350 ft above ground

cos(45)=.707

horizontal extent of plate 500' at 0deg, 353 ft at 45deg, so jacks will tilt by 150feet, or 12 deg
If the jacks are not limited to axis of 90 deg (say east/west,north/south) then the tilt will be in 2 directions.

If plate broken into smaller sections, then shadowing will occur.

The shadowing will be independent of the plate size used.

Visibilities from inside the current sink hole

Laser scanning data from the center of the dish (atop ao9 monument) was used to look at the elevation range available from different locations within the sink hole.

Caveats:

data was taken on 11mar20 using the p50 scanner sitting atop ao9 monument

The monument mount + scanner was about 15 feet above the ground (but so are 10meter telescope dishes:)
The scanner ran 360 deg, -20 to 90 in elevation in 270 range mode (i think)

We measured the dish, not the ground. The height from above the ground can go from 1 meter to say 10 meters?
We scanned 0 to 90deg in elevation,, but we did not get a return from most of the hillsides.

We were able to measure the northwest hillside and a bit of the north hillside

Some distance/angle values (some are more accurate than others. don't believe all of the digits beyond the decimal point :)

ao9 monument mount above monument marker p50 (rotation axis height)	4.036m (13.242') .25 (.076')
diameter of dish	305m (1000')
radius of curvature of dish	265.176m (870')
max zenith angle	35 deg
height bottom of dish to edge of dish	48 m (157')
tiedown block horizontal offset from center of dish	58.5m (192')
tower center horizontal offset from center of dish	213.360m (700')
elevation bottom of dish (above sea level, not sure the datum)	231.717m (760.228')
elevation top of towers (working point) (before collapse)	422.605m (1386.5')
tower working point(on saddle) to top of cement tower	about 1.5 m (5')
elevation (above seal level) base of towers (from top of base) (from 2017 sag survey) [t12,t4,t8]	[346.32,346.82,311.74]m [1136.22,1137.86,1022.77]ft

Images of blockage of telescope in dish vs azimuth:

Using the p50 laser scanner data i've plotted the elevation angle where the a telescope would see an obstruction.
This has the p50 15 feet above the ground and saw reflections from the dish (rather than the ground)
The p50 only got a reflection from a small portion of the hills so this is a lower limit.

blockage vs azimuth from center of dish (.png)

the horizontal axis is azimuth. north=0, CW is positive
The solid area up to 18 degrees is the main reflector
The horizontal dashed lines above this are from the ground screen
The largest elevation of 32 deg at az=-60 is from the hillside in the northWest
This looks like 45 degrees za/elevation is do able from the center of the dish.l

blockage vs azimuth for antennas at the tiedown blocks radius (.png)

The tiedown blocks are 58.5meters (192') from the center of the dish. This would give a radius of 117 meters
The bottom of the dish is flat to at least the tiedown blocks. It then starts to slope upward (at least at td12)
A dish was placed at the height of the center of the dish, 58.5 meters from the center of the dish, and then moved 60 degrees in azimuth to give 6 separate plots.