This might sound silly to all you Brits, but I was so excited to see these gas structures when I was in the UK. We did have them in Australia but they were all gone by the time I was born - I think because we produce our own gas and it travels via pipes. I had always seen them on British TV shows, and seeing them in real life was a huge “yep you’re in Britain now” moment. I was also captivated by the old power station near Sheffield (Stellafield?) when I saw it. Like many Aussies, I grew up watching lots of TV shows imported from the UK and stuff like gas holders always looked so interesting and exotic to me.
Log periodic aerials are used for both receive and transmit on many directional relays. Your picture example of "some need many" is an example of a tight transmit pattern in two directions. Stacking is usually used to constrain the spread of the signal in one dimension, concentrating the effective power to where it's most needed. In the case of the stacked dipoles inside the shroud on the gasometer, that will vertically squash the doughnut shaped radiation pattern, and the mounting pole/plate will act as a reflector to null the cardioid pattern behind the aerial. With some clever phasing you can even cause the radiation pattern to tilt.
@@michaeltonge1971 That sort of arrangement is very common at low power relays. The incoming signal is usually from a HP log periodic further down the mast. I photographed many in the Greater Manchester, South Lancs and North Wales areas for the MB21 website.
As many people don't know what a gas holder is... There was originally a metal shell (like an upside-down coffee mug) that sat inside the structure you see today. There is a huge hole below ground level and, as gas was pumped in, the gas holder vessel would rise up inside this structure. In times of high demand in the local area (meal times, cold weather etc) it would drop down again, maintaining a constant pressure to the system. The entire thing floated on water, ensuring a gas-tight seal. Originally, it stored "town" gas, made from coal, which was rather dirty to produce and use. After natural gas was discovered in the North Sea, the system moved over to this, and eventually the gas holders were mostly removed.
On Christmas morning you could see them dropping as everyone cooked their turkeys. In the part of the country where I grew up they were known more commonly as Gasometers. The old Bristol Rovers football ground at Eastville Park had two of them behind the home stand, leading to the "Gas Heads" (or simply "The Gas") nickname for the supporters and the team itself.
Interesting how the radio spectrum gets used in different countries. Where I live in Southern California USA, 700 mhz is used by our local sheriffs department’s encrypted radio system.
Anytime I hear "Crystal Palace", I can't help but think of WarGames (it was used as NORAD - Cheyenne Mountain Complex's callsign), even though the real Crystal Palace (and the eponymous transmitter) predates the movie by many decades.
I worked for a well known OPCO in the early 00s and we (radio engineers) used to go on BG H&S courses on how to work on Gasometer sites. We were using the structures for certain things, it was meant to be a big roll out but after the initial few I think the idea must have been binned. The few sites I worked on have all now been demolished and the land either built on or its just empty land now. /cool story bro
gasometers are so cool- being able to tell the status of a building just by looking at it is neat. I always thought they should add that artificially to other buildings, like if the building is a huge telecom hub like 1 wilshire in los angeles, add lights to the outside that show how busy it is there'd be no real use to it, but it just would look cool
Many people don't know but this Innocent looking antenna is owned by SHADOW. Is is one of many covert antennas across Great Britain used for tracking purposes. The collected data is then sent to Moon Base Alpha.
That happened the same here in North America. The 700 MHz and now the 600 MHz band were vacated and now they are mainly being used for cell phone usage. I live in Mexico and in my city were 3 channels above channel 38 (in the ATSC standard used in 🇨🇦, 🇲🇽 and 🇺🇲 here is where the 600 MHz band started) and those 3 channels were relocated to lower channels, 14, 15, 16 and 17, which are located near the 400 MHz band and people had to make a rescan in order to receive the new frequencies.
Brilliant stuff, Lewis! I certainly appreciate your braving the North London weather to take on this field work. Now, off you go back to Sunny Manchester, cheers! 🙂
Like those aerials seen at the beginning….. Near my place of work there are council facilities + separate electricity site….those small sites you see on the roadside. Council site has what looks like v old VHF vertical aerials…not pointing at the main Mendip or wenvoe or radio relay masts. I don’t what they do or where they are pointing at. The small electricity site has what looks like long UHF tv aerials…again, not seeming to point to any known masts. I have noticed a number of such sites are like this….no idea what they are or where they are pointing, and these sites aren’t new-been there for years…but only recently got these aerials added.
As far as the TV antenna goes: Dipoles in that tall slender structure, or are they slot antennas? And what polarization do you use in the UK for television? In Canada/US we have horizontal polarization. The thought was that this would pickup less man made noise. (Our NTSC system used AM for the picture. (but the sound was FM, that's part of why Mrs. Armstrong got quite a settlement, by the way!) so the slot antenna magically flips the polarization to vertical. 73 DE W8LV BILL (and sometimes, W8LV/VE3)
Sorry, you said Muswell Hill. I immediately started hearing Madness - Driving in my car.. Just like week I changed the oil, the rocker valves and the coil.
Am I reading the map at 4:31 right? That footprint is about 2 miles wide from northeast (the transmitter) to the southwest edge? I can see why they need only 5 watts.
Satellite TV? What is that? We only have a few radio signals. We have 3 VHF television channels and about the same on longwave. I'm currently building a crystal set. We hope to receive Morse by 2025.
that will be because the old services (including possibly analogue?) were in Group C/D but the C/D group was consumed by 5G broadband signals, so the new frequencies are in channel group B. C/D aerials won't work in Group B, hence the need for a new aerial (either Group B or wideband).
Its radiation pattern is back towards CP to cover the area not covered by higher ground towards CP. Anything north in the shadow of the structure probably uses Hemel.
Right so when the drone first flew over, looking down, what you’re seeing is the sealed end of an upturned cylinder, sometimes like a cup or sometimes made of telescopic sections (flexible seal round the joins, likely greased leather or vulcanised rubber) that is open on the bottom side. How it works is this - Imagine a large drinking glass, sitting on its rim in a pool of water the same depth as the glass. The glass is full of water so has ‘sunk’ so the bottom of the glass is at the level of the water (almost). Now, pump your gas into the open end of the glass/cylinder and watch it rise up out of the water. A telescopic cylinder would do the same. The gas is prevented from escaping by the water the cylinder sits in. That’s how the gas is stored. As the gas is used, the weight of the cylinder naturally pushes down the gas and keeps pressure. The framework is there simply to support the holding cylinder from toppling over. And they are in fact called ‘gasometers’.
@@sprint955st Many thanks for explaining. I had (joking aside) realised the gas must be in the underground cylinder, but had no idea what the framework was for.
