144 mhz turnstile antenna

Carol F. Among horizontally polarized antennas used for weak signal VHF terrestrial communications, Cebik 4 analyzed the Big Wheel, an omnidirectional array of three full wave loops, as a 1. He proposed as an alternative design an array of three discrete dipoles fed at their low impedance points, either in an equilateral triangle or curved into a circle. This study uses NEC modeling to compare the expected performance of each of these antenna designs against a turnstile antenna.

All antennas were modeled with 4nec2 at 0. Although the overall expected performance of each of the models is similar, the following factors should be considered:.

Composite of all MHz Antennas at 0. The Cebik Triangle and Wheel antennas more closely approximated an omnidirectional pattern with 0.

The Cebik Triangle and Wheel antennas showed deep nulls in their radiation patterns toward the zenith while the turnstile antenna had a -1 dBi minor lobe in that direction. The turnstile antenna exhibited the least suppression of vertically polarized noise.

The losses incurred in the additional stacking and phasing harnesses may diminish or negate the expected gain in any particular antenna design.

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Deviations in the antenna and phasing harness dimensions can significantly skew the radiation patterns.Carol F. The halo, turnstile, eggbeater and Big Wheel are omnidirectional horizontally polarized antennas used for weak signal VHF terrestrial communications. Cebik 3 duly described the benefits and problems of each of these antenna designs. These antennas can be stacked to increase gain at low elevation angles and to decrease sensitivity to noise from high elevation angles.

This study in six parts presents NEC models that compare the expected performance of these antennas.

The Turnstile Antenna

Each antenna was modeled with 4nec2 singly at 0. Although the overall expected performance of each of the models is similar, the following differences should be considered:.

The turnstile and Eggbeater Antenna more closely approximated an omnidirectional pattern with 0. All antenna types showed similar elevation radiation patterns with gains of The Turnstile Antenna exhibited the least suppression of vertically polarized noise. The dimensions of the turnstile and eggbeater antennas need be precise because deviations in the antenna dimensions can significantly skew the radiation patterns.

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Summary of Results. Cebik Triangle. Cebik Wheel.Post a Comment On topic comments are welcome. Junk will be deleted. Weather satellite reception is described here. A quadrifilar helical antenna is described here. Engineering, is the art of making what you need. The right hand polarization actually becomes visible in the radiation pattern plot, which I found really cool.

Another option is to cut up a Carrefour aluminium clothes rack made of 6 mm aluminium tubes, but I like the idea of a roll-up antenna for training - It is easy to stow and transport in a car for the next time I get the urge to bark at the moon. For the rod, get a 1. The boat anchor is a bit light - good for a canoe maybe. So, one can take some implements from the French Revolution and turn them into a modern day satcom antenna. Circular Polarization.

The result is that the RF transmissions also rotate. If you would use a fixed dipole antenna to work a satellite, then the signal strength will fluctuate rapidly. You can get polarization naturally, with a helical antenna. Otherwise, you can make a rotating field by setting up a 2 phase electrical motor. The speed of light in RG58 copper wire is 0. The NEC2 Card deck:.

How to Make Your Own Homebrew Omni 144 MHZ VHF Antenna

Impedance Match. The impedance of a dipole antenna in free space is supposedly 73 Ohm. The parasitic elements of a Yagi-Uda, reduce the impedance to something closer to 50 Ohm. You can fine tune the impedance by adjusting the distance between the reflector and the dipole. The thickness of the elements also affects the bandwidth and the impedance. In this dual design, there are many elements and the impedance is about 21 Ohm. Therefore, it is good to hook the antenna up with RG58, 50 Ohm coaxial cable.

The coaxial cable is unbalanced, while the dipoles are balanced. It is therefore necessary to add some inductance to the cable shield, by wrapping five to ten turns around the rod, just below the driven elements. Note that the wrap only affects the shield.

The centre conductor is shielded and therefore is blissfully unaware that it is wrapped around a stick. Alternatively, clamp a ferrite around the cable.

144 mhz turnstile antenna

This will prevent the cable shield from radiating and disrupting the antenna pattern. Again, the ferrite will only affect the shield, not the inner conductor. Conclusion A tape measure antenna is not rugged and sooner or later a wire connection will break, but the advantage is that one can fold it and get it in and out of a car, making it good for educational use. La voila!

Labels: HW.About 2m Quad Turnstile Antenna The resource is currently listed in dxzone. The main category is Antennas for 2 meters band that is about Antenna projects for MHz. This link is listed in our web site directory since Wednesday Jan 15and till today " 2m Quad Turnstile Antenna " has been followed for a total of times. So far no one has rated yet, so be the first to rate this link! The scale is 1 - 10, with 1 being poor and 10 being excellent.

Webmaster, add a Remote rating Related links We thought you might also be interested in these additional resources we selected from the same category: A Mhz J-Pole Antenna - A 2 meter Mhz J-Pole antenna that is inexpensive, and easy to bu Simple j-pole antenna for 2 meter - how to build a J-pole antenna for 2 meter band with many photos ecc Visit this link 2m Quad Turnstile Antenna Visit Site Share this resource Share this link with your friends, publish within popular social networks or send it via email.

Real Hams review new sites every day sincefor potential inclusion in the Directory, and to evaluate the best place to list them.

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Sign up to our Newsletter Get our latest news and links in your email. Operating Modes Operating Aids. CB Radio Antique Radio. The loops are made of 10 mm round aluminum tube. No bending pliers was used to gently bend 90 degrees to obtain a square with 53 cm inner sides. Each loop has an impedance of approximately Ohm.

To connect both radiators in phase, a quarter wave long feeder of Ohm is required. Related links We thought you might also be interested in these additional resources we selected from the same category: A Mhz J-Pole Antenna - A 2 meter Mhz J-Pole antenna that is inexpensive, and easy to bu Share this resource Share this link with your friends, publish within popular social networks or send it via email. The DXZone is the largest human created and maintained library of web sites dedicated to Amateur Radio, currently lists Get our latest news and links in your email.

Service provided by Google FeedBurner. Visit Site.About A MHz turnstile antenna The resource is currently listed in dxzone. The main category is Antennas for 2 meters band that is about Antenna projects for MHz. This link is listed in our web site directory since Friday Aug 26and till today " A MHz turnstile antenna " has been followed for a total of times. So far received 3 votes for a total score of 6. The scale is 1 - 10, with 1 being poor and 10 being excellent.

144 mhz turnstile antenna

Webmaster, add a Remote rating Related links We thought you might also be interested in these additional resources we selected from the same category: A Mhz J-Pole Antenna - A 2 meter Mhz J-Pole antenna that is inexpensive, and easy to bu Simple j-pole antenna for 2 meter - how to build a J-pole antenna for 2 meter band with many photos ecc Visit this link A MHz turnstile antenna Visit Site Share this resource Share this link with your friends, publish within popular social networks or send it via email.

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Building A Simple and Inexpensive Satellite Ground Station – Part 1

Operating Modes Operating Aids. CB Radio Antique Radio. A MHz turnstile antenna. Related links We thought you might also be interested in these additional resources we selected from the same category: A Mhz J-Pole Antenna - A 2 meter Mhz J-Pole antenna that is inexpensive, and easy to bu Share this resource Share this link with your friends, publish within popular social networks or send it via email. The DXZone is the largest human created and maintained library of web sites dedicated to Amateur Radio, currently lists Get our latest news and links in your email.

Service provided by Google FeedBurner. Visit Site.When we think of ground stations for satellites, large antenna arrays and dishes immediately come to mind, along with a lot of expensive electronics. But you can receive transmissions from many satellites using very inexpensive equipment.

Using these components and software, you should be able to hear transmissions from several different satellites. Most of the frequencies of interest are below MHz.

One of the largest challenges is determining which satellites are still functioning, especially with the CubeSats with their relatively short lives. This can dramatically lower the cost of the radio for a simple system. Inexpensive software defined radios have only recently become available with the introduction of the Realtek RTLU in [1]. Most of these will tune from about 30MHz to 1. You can purchase up converters and down converters to extend the range.

More sophisticated SDRs can run several thousand dollars. The Low Noise Amplifier is optional. And it is very useful to overcome coaxial cable loss if the antenna and receiver are located at some distance from each other.

This is sufficient to get started and verify that your radio is working. But as you try to tune in satellites, you will need a better antenna, especially as you receive data from the NOAA weather satellites and CubeSats.

We built the Quadrifilar antenna and have been quite pleased with the performance. The Omnidirectional antennas are easiest to begin with, since you do not need to worry about pointing the antenna at the satellite while receiving. The Quadrifilar Helix QFH Antenna is an excellent omni-directional antenna that can be built relatively easily for any of the frequencies of interest.

The Turnstile antenna is another excellent and slightly easier to build omnidirectional antenna for the frequencies for many of the weather and CubeSats. We have not tried this antenna, but will. In part twowe will talk about the software and give more details about antennas.

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Notify me of new comments via email. Notify me of new posts via email. Skip to content By Bob and Jann Koepke When we think of ground stations for satellites, large antenna arrays and dishes immediately come to mind, along with a lot of expensive electronics. A Personal Computer — laptop or desktop. Having more than one display helps Cabling to tie all of this together Using these components and software, you should be able to hear transmissions from several different satellites.Recently our 1.

To our amazement we found no problem as it keyed right off with the initiation of 12 V and a shorted key line. Anyway, I did a good going over of it and peaked it up whether it needed it or not. It appears to be very healthy with a good 30 watts of output on a Bird wattmeter.

It does take a bit of planning to get a beacon back into service at our South Park site, a trip that consumes the better part of a whole day. Over a couple of week period I have received reports ranging from an S-3 in Fort Collins to 40 over 9 in Bailey. As it has performed so well in beacon service here I thought that with the recent resurgence of activity on the 1. The Turnstile is basically a pair of orthogonally positioned dipoles sharing a common axis, crossed dipoles if you will.

Since the pair of dipoles is physically 90 degrees out of phase with one another they need to be fed 90 degrees out of phase with one another via a quarter wavelength section of coaxial line. The phasing section is made of 75 ohm line in order for the pair of dipoles to be matched to a 50 ohm transmission line.

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Since this type of antenna or array of dipoles will need to be broken in the center I elected to use flat stock elements rather than round stock. My intention was to mount the Turnstile on a push up pole, so I built the pair of dipoles on a hub of sorts. The elements were made of flat stock 0. I used 0. In this case, for resonance at I made a 90 degree bend at one end of the elements of 0. If it is desired to make elements any where in the 2M, 1.

Then add 0. Drill 4 6 0. The screws 6 used to attach the elements to the hub will need to be long enough to hold a second nut to attach the 50 ohm transmission line solder terminal and, in the case of the first dipole hooked up, it will be holding a pair of solder lugs. Preparation of the phasing section follows; the phasing line will be a quarter wavelength section of 75 ohm RG coax. The length of the phasing section is determined by the following equation:.

The V P is the velocity factor of the coax. In the case of RG that uses a dielectric of polyethylene, the V P is 0. Example: The phasing line for a Turnstile to be used on a frequency of Remove approximately 0. Comb out the braid and twist it into a single wire.

144 mhz turnstile antenna

Solder a 6 solder terminal to the twisted braid wire shield taking care not to melt the dielectric of the center conductor. Do this to both ends of the phasing section. Attach one end of the phasing section to the dipole screw set on which the 50 ohm transmission line was attached previously, braid to braid and center conductor to center conductor.

The other end of the phasing section is to be attached to the other set of dipole screws. Order does not matter in this instance. Order would matter if you were to use the Turnstile as a feed for a dish with a reflector behind the Turnstile by 0. Then, depending on which way the braid and center conductor were connected to the second dipole, this would determine if the circular polarization of the array would be left hand circular polarization LHCP or right hand circular polarization RHCP.


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