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What the World Needs Now -- Broadband Antennas for Metal Shops  

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September 1, 2011 

I recently moved to Lubbock Texas.  Iím still in the process of setting up my new electronics lab in my 30 foot by 40 foot all metal shop.  The shop is some 100 yards from the back of my house.  Although I have good cell phone, WiFi and Cordless phone signal strength over my entire acre lot, all those signals drop to zero once inside my shop.  The metal acts as a large Faraday shield, blocking nearly all RF.  The only radio signal which we can pick up inside comes from a strong AM station, whose radio tower is close by.  Nearly all other AM and FM stations are useless.  I sure wish there were some kind of broad band antenna system which could route RF signals into and out of a metal shop.

Dave's 1200 Square Foot Shop
The radio spectrum of our modern society is vast.  AM radio starts at 530KHz and extends to 1.6MHz.  FM radio starts at 88MHz and ends at 108MHz.  Then, there is the 800MHz band needed for many cell phone services.  Computer WiFi connections operate at 2.45GHz.  My cordless telephone runs at 5.8GHz.  I doubt that any one antenna would work for all of these signals.  I fear that I will have to use separate antennas for each of the devices I wish to use inside the shop.
As an example, a solution which seems to work for the WiFi link to my shop computer was to first buy a WiFi USB adapter, which contained a SMA external antenna connector.  I then bought a nice high gain WiFi antenna and mounted it outside the shop.  Finally, I punched a hole in the side of my shop and strung a coax cable from the outside antenna through the metal shop side to the SMA connector on the adapter.  That worked quite well for the computer and I now have Internet access in the shop.  But, what do I do with my cell and cordless phones?  Also, my wife often likes to listen to some talk and oldie AM and FM radio stations while working in the shop.  Perhaps I will have to mount more antennas on the outside and with the aid of some more coax cables, to bring those signals to the inside.  I may have to buy a good quality radio receiver, which has an external antenna connection.

Until I have time for some final solutions, I might try some low tech method for the two telephones.  I could mount a box on the outside of the shop, where they can receive the signals from the house, and develop a beeper system, which would drive a beeper on the inside of the shop whenever either phone rings on the outside.  We would then have to go outside the shop to pick up the phone.  This would not be ideal but at least we would not miss an incoming call when in the shop. 

If you have any other ideas, I would love to hear about them.

Cell Phone 5.8GHz Cordless Phone             WiFi Adapter
WiFi Antenna  Coax Cable WiFi Antenna Outside Daveís Shop
AM/FM Radio External Antenna Connector

November 2011

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Envelope
Circuit
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Good Idea
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What the World
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