Introduction: Make a High Performance TV Antenna From a Satellite Dish and a Few Parts

I made a high performance TV antenna with a surplus 24 inch satellite dish and some scrap metal and wood.

Step 1: Parts and Tools Needed

1) 24 inch satellite dish and mount (can usually be purchased at surplus electronics stores, ham swap meets or ebay) .

2) Two pieces of scrap wood (1/2 by 4 by 24 inch) The lengths can be cut later.

3) Mini project box. (Radio Shack)

4) Liquid Vinyl Coating of the type to coat tool handles (Home Depot)

5) Gray spray paint (Automotive supply store)

6) RG6 Coax 50 or 100 feet depending on your needs (Radio Shack) I recommend RG6 over RG59 because it has lower losses at UHF frequencies.

7) Sheet copper or sheet steel

8) Aviation shears for cutting sheet metal (Home Depot)

9) Female Chassis mount "F" Connector (Radio Shack or other electronics store)

10) Needle nose pliers, electrical solder, adjustable wrench or socket set, multi-bit screwdriver etc.

11) 10 foot length of galvanized EMT (Electrical Metalic Tubing) 1 inch in diameter. (Home Depot)

12) 3 foot length of ABS black plastic pipe 1 1/4 inch in diameter (Home Depot)

13) Assortment of wood screws.

14) Piece of plumber's metal strapping (Home Depot)

Step 2: Explanation of Technical Details

The actual receiving part of this antenna is called a Bowtie or Butterfly antenna. It is useful for TV because it has a wide bandwidth and has an impedance which is close to the 75 ohm TV coaxial cable impedance. This allows it to be connected directly to the TV. Normally this type of antenna has a flat reflecting element that is placed behind the bowtie. ( I originally experimented by using a flat reflecting element but found the performance inferior to the dish.) This is then placed in the direction of the broadcasting station to be received. I thought that I would try using a variation of this by placing the bowtie in the focal point of a satellite dish with the dish pointed at the signal of interest. I used an online calculator to calculate the dimensions of the bow tie antenna at approximate 600 MHz or American broadcast channel 35 as this was the most distant channel that I wanted to receive. The online calculator can be used here. http://www.changpuak.ch/electronics/Butterfly-Ante...

After assembly and testing, I found that I received 11 channels in my difficult deep fringe area with multiple hills around. I was extremely pleased with the performance of this antenna. Once the antenna is assembled, I will explain some of the adjustments to make as this antenna is extremely sensitive to the direction and elevation adjustments of the dish.

Step 3: Layout of Bowtie Antenna on Wooden Frame With Dimensions

The picture gives the width of the whole assembly as being 15 inches from end to end. The sizes of the wood pieces are not critical but the sizes of the triangles are. For the center frequency of 600 mHz the dimensions of the triangles are 5 inches high by 7 1/4 inches wide. There should be a gap of 1/2 inch between the two pointed ends of the triangles and this is where the two terminals of the RG6 coax are soldered.

Step 4: Mount Plastic Project Box Directly Between Bow Ties.

Before mounting plastic project box, drill a 1 inch hole in bottom directly exposing ends of bow ties. Also drill a 1/4 inch hole in the side of box that is going to face down. This hole will be for mounting the female "F" connector. Make solder connections from center conductor to one side of bow tie and solder the other bowtie to the outside conductor or ground of "F" connector. The project box should be mounted with two wood screws.

Step 5: Once Box Is Mounted; Weatherproof Bow Ties With Liquid Vinyl.

Once connections inside box are made, they should be secured with hot melt glue. The cracks where the plastic box meets the wooden frame should also be sealed with hot melt glue. Once this is all dry the metal should be painted with liquid vinyl. Paint the metal in thin coats letting each coat dry before applying the next. Make sure even the edges of the metal get coated.

Step 6: Put Final Coat of Automotive Spray Paint on Whole Assembly.

I picked this color because I happened to have it around and it matched the color of the satellite dish. I sprayed the whole assembly including the black project box with the cover on. The only part that I covered with masking tape was the "F" connector where it came out of the box. This is where the coaxial cable connector that goes to the TV attaches.

Step 7: Assembly Should Be Mounted on Arm of Satellite Dish.

I mounted the wooden part of assembly to the metal arm of the satellite dish with one screw through the metal arm and four screws through metal strapping. This ensured that the assembly and satellite dish would hold together in foul weather.

Step 8: Attach 3 Foot Length of Plastic Pipe to Satellite Dish

attach a piece of black plastic pipe to back of satellite dish as shown. 1 1/4 inch fit in the mount perfectly. Tighten screws in mount so that it doesn't move. This will later slip over the 1 inch by10 foot length of galvanized EMT (Electrical MetalicTubing). A hole was drilled in the plastic pipe into the EMT and a self-tapping screw was inserted to to keep the satellite dish from moving free of the EMT. More holes and screws can be added if they are needed.

Step 9: Attach Coaxial Cable to Female "F" Connector and Waterproof With Electrical Tape.

The coaxial cable male "F" connector should be hand tightened and then all metal parts should be weatherproofed with a few layers of flexible electrical tape. The lid of the plastic box should also have a couple of layers of electrical tape to cover the seams.

Step 10: Final Mounting and Aiming.

The antenna should be mounted in a place that is away from any obstructions, especially metal ones. It is preferable to keep it away from trees as they will have a definite blocking effect on the signal as these signals are in the lower microwave range. As this antenna is extremely directional, it is recommended that it be aimed in the direction of the weakest station desired. Local stations will come in well without aiming. For extremely distant signals, better reception might be obtained by adjusting the elevation adjustment of the dish. Otherwise just keep the dish at 90 degrees to the horizon. Play with the direction and set the TV to scan. If you have distant stations in a number of directions turn the antenna at 15 degree intervals and scan to see which direction gives you the most stations. This type of antenna is very broadband but you can still optimize it for a certain range of channels by changing the size of the bow tie. As mentioned earlier in the article, this antenna was optimized for 600 megahertz or channel 35.

Comments

author
mr electro (author)2016-12-11

I installed this antenna at the home of a "cablecutter" friend of mine about four months ago. The desired stations are about 40 and 45 miles away. The signal is fed to the TV through 50 feet of RG6 cable without an amplifier. Around 20 stations are being received with a clear steady signal regardless of the type of weather including heavy snow.

author
Hippie1951 (author)2016-10-01

You can buy some aluminum roof flashing, and rivet or attach with screws to the face of the dish making it flat. the bowtie/dipole can be moved away with an addition to the arm, with wood or metal. 3db gain as mentioned before is not too bad anyway. You can figure the size of bowtie element by dividing 432 by the middle frequency you want to watch. The distance from bowtie can be found by dividing 234 by the same frequency. These figures will get you close enough to be able to get very decent results. I have used 12 gauge solid copper wire in a 26" circumference, vertically and supported by 1/2" PVC X boom at 20' and received TV from distances of 90 miles regular. The Digital signals are broadcast at much higher power than analog were. I was against the transition to digital at first. Now, it's awesome!!
Old Ham Op too....

author
tinkernick21 (author)2016-08-09

Awesome instructable but what's the range on this? I picked up a roof mount 150 mi antenna (with motor for adjustments) for $50 on Amazon. Just not sure it's worth it.

author

Of course, cliams of reception range should be taken with grain of salt. UHF reception has been subject to a lot of factors. Look up the TV stations of interested at the FCC website. You should be able to find coverage area plots. In the event you are in a null of the pattern. there may not be much you cant do about that except to twist the antenna around to see if you can find a signal reflection off one of the stronger lobes. An amplifier mounted at the antenna may or may not help if you are in a null.

author
mr electro (author)tinkernick212016-08-09

Range depends on the height of your antenna, the terrain and obstacles between you and the TV station you are trying to get. You might be able to get 150 miles, but this is not predictable as UHF signals are also affected by atmospheric conditions. The waves are bent and reflected by rain, snow and the layers of different temperature air in the atmosphere. A rotator is a must if you're favorite stations are in different directiions. In my situation, my local stations can be received without aiming the antenna , but the TV stations of choice are all in the same direction so a rotator isn't all that important. I used to watch a UHF channel around 150 miles away on a regular basis, but it was back in the days of analog TV and I was on a 300 foot hill and there were no obstructions between my location and the transmitter, as their transmitter was on a mountain. These new TV's are much more fussy than the old analog TV's. The old analog TV's would show you a deteriorating picture until there was no signal. Then you would see "snow" or "raster". The modern digital TV's have a bottom level signal strength that they are programmed to ignore if the signal is any weaker than it. Thus when you are scanning for channels, it will ignore any channels that have a signal strength below this level. You need to be very patient when you are looking for signals, aim and scan, re-aim and scan. I hope this answers your question.

author
mr electro (author)2016-08-11

The whole point of this exercise was to put together a surplus satellite dish and some scrap wood and come up with a useful product. I make no claims that this will outperform expensive professional antennas designed with programs such as AntennaMagus and tested in specialized labs.

This antenna will have performance similar to a Bowtie with a corner reflector which typically have gains of 10-15 dB. According to Wikipedia, this antenna is a "medium gain antenna". Changing the distance between the driven element and the reflector might vary the performance a little bit resulting in optimum gain and match to the feedline. https://en.wikipedia.org/wiki/Corner_reflector_an...

I understand the theory behind offset-fed parabolics and there was no intent on my part to use this as one would use a satellite dish where gains of 50-60 dB can be realized.

Thank You for your feedback.

author
LilGrub (author)2016-08-11

Umm,

Not to dump on your project too hard - but what you've constructed is anything but a 'high-gain TV Antenna'.

At best, your design might manage an additional 3dB in gain - above that of what a half-wave dipole mounted in free-space - would otherwise achieve.

Given that the wavelength of even the highest UHF TV signal allowed today in the US, ( which is now UHF CH50 - 683-689MHz for ATSC-Digital TV ), is still some foot-and-a-half in size, you'd actually need a dish with a diameter of around twice as what you are using - to even compete with any $60.00 dedicated high-gain UHF TV Yagi-Antenna.

The dish you've elected to use is also an offset-fed parabolic, ( meaning that it's 'focus' is not direct in front of the dish, but slightly below it ), resulting in your driven element not even achieving any advantage of RF-Gain - simply by it not being placed at the dish's 'Hot-Spot' focal point.

A dish this size has a focal point SUBSTANTIALLY smaller than the driven element you have constructed, resulting in pretty well zero gain achieved anyway - even if you had managed to place it correctly at the dish's focus.

( Notice just how small the feed-horn 'face' of the Dish's LNB is? - the part that you removed from the original section of the dish's arm - This is how 'tight' the focal point of a dish this size actually is - thus clearly unsuitable for a driven element of the dimensions that you have constructed… )

Satellite Pay-TV Providers also deliberately use offset-feed dishes to allow the focal point for the Dish's LNB to be specifically below the dish.

The reason for this is to allow the entire assembly to be tilted only moderately back, and still achieve a perfect 'aim' of the overhead satellite, without the LNB 'blocking' any dish's view of the sky.

To re-use a dish like this for any application of capturing signals at ground level, both the new driven element must remain placed at the dish's focal point, and the dish then 'tilted' down at an awkward angle - to now capture signals coming from the horizon - instead of from the sky above.

In closing, Parabolic Dishes are simply not used for frequencies below roughly 1GHz, ( 1000MHz ).

This is because the physical size required of a dish, ( for wavelengths below 1GHz ), is way too big - when compared to simpler, smaller, cheaper and easier to construct designs, based around a classic Yagi-Antenna.

Placing your driven element against the dish in this fashion, has resulted in you constructing nothing other than a 'reflector-backed' dipole - or, something resembling an unoptimised two-element Yagi.

Some additional information to help you to amend you design -

To understand why the Focal Point is deliberately off-set for Satellite Parabolic Dishes;

https://en.wikipedia.org/wiki/Offset_dish_antenna

To understand why a dish this size has such a deliberately 'tight' focal point;

https://en.wikipedia.org/wiki/Satellite_television

author
TonyF65 (author)2016-08-09

cool

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author
Dr. Gonville Farnsworth (author)2016-08-02

Outstanding 'ble. I am in the process of planning a new telly antenna build and had not decided what to build. This is certainly worth a second read and further invedtigation. Finding the dish will be the easiest part. A quick listing on Craigslist will almost certainly turn up one for free.

As for the antenna elements, when you use the calculator should you enter channel frequency only or is there more to it? We have channels from 15 to low 40 ' s(actual uhf channels) so the broadest spectrum would be needed. Most are within 45 miles of fairly flat terrain. So, would you pick an element tuned for the middle of the uhf channel spectrum? Thanks for great contribution.

author

You would enter channel frequency in the calculator and pick it for somewhere in the middle of the UHF band as you said. This antenna is very broadband so you have a lot of leeway. You could use channel 30 as your middle channel. The frequency of channel 30 is 566 MHz. Here is a link to channel frequencies

https://en.wikipedia.org/wiki/North_American_telev...

Good Luck

author
BeachsideHank (author)2016-07-31

Well done, anytime we can harvest free and legal airwaves content, we win:

https://www.instructables.com/id/A-Scrap-TV-Becomes...

Since my build was an indoor version, I added a rotator mechanisim to maximize channel reception:

https://www.instructables.com/id/A-Microwave-Oven-H...

author
mr electro (author)BeachsideHank2016-08-01

I liked your indoor antenna. It's nice looking as well as practical.

author
BeachsideHank (author)mr electro2016-08-01

Thank you!

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