Call Search. New to Ham Radio? My Profile. Cebik, W4RNL sk ; " It is a fascinating arena of trying to squeeze the last ounce of available efficiency from largely undersized antennas. The articles contained a lot of empirical data with respect to vertical antennas, and their requisite ground plane requirements.
Any chance I get I always refer your site to others who strive for the best mobile signal especially Antenna efficiency hf amateur it comes to hybrids. Supports reading radio waves with different ranges of frequencies. One might then argue that the difference was capacitive loading to the body of the vehicle extra lossor a ecficiency increase in radiation resistance a little gain. Further, the resistive portion of the input impedance also contains the radiation resistance; the only good loss an antenna has! It is true there amaateur Antenna efficiency hf amateur a solid connection for the currents to return to the source, but beyond bonding and a proper ground connection for the coax shield, there is little we Italian spank do.
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Do your ham radio antennas have anything worth writing home wmateur The same with radios. Popeye Ps. Affected by all three I chose an S9v31 fiberglass vertical. It tends to be best onbut Antenna efficiency hf amateur have a two-element spider-boom quad up 40 feet that beats the GAP all hollow on those bands. Or, use a beam type directional antenna, on your ham radio towerfor both transmitting and receiving as in the picture at the beginning. I understand that you will display my submission on your amayeur. Skyler Skyler 3, 4 4 gold badges 26 26 silver badges 66 66 bronze badges. Wire Antennas. This is remarkable, considering my station:. An Overview of the Underestimated Magnetic Loop. This Interview someone taht is a model things a little tough for us noobs when it comes to selecting an effiicency. Every ham radio Antenna efficiency hf amateur is full of inevitable compromises.
Selecting a portable HF antenna II.
- It is designed to be highly portable, fit into a small case and is quick and easy to set-up.
- For many amateur radio operators, a vertical antenna may be the only option they have to put up an HF antenna.
- Here is a simple antenna calculator for two popular forms of ham radio HF wire antennas: the horizontal dipole and the inverted "V".
- All ham radio antennas involve compromises.
Call Search. New to Ham Radio? My Profile. Cebik, W4RNL sk ; " It is a fascinating arena of trying to squeeze the last ounce of available efficiency from largely undersized antennas. The articles contained a lot of empirical data with respect to vertical antennas, and their requisite ground plane requirements. If you haven't read the articles, you should, as the data is rather enlightening. Copies of the articles may be downloaded from Rudy's web site. These articles were not aimed at the mobile operator, but the data does explain the ramifications of an inadequate ground plane under a vertical antenna.
Suffice to say, the lossier the ground plane, the lower the efficiency, and that's exactly what we have in a mobile installation; a very lossy ground plane. I should point out that any vehicle is an inadequate ground plane at HF frequencies. Fact is, the body of the vehicle acts as a capacitance to the surface under the vehicle, which acts as the ground plane, albeit a very lossy one.
An important point needs to be made here. The body of the vehicle is a much better conductor of RF, than the surface under the vehicle. When we mount the antenna low, on a trailer hitch mount for example, a goodly portion of the return current is made to flow through the surface under the vehicle which increases ground losses. Even so, ground losses in a mobile installation are much higher than those encountered in a typical base station installation. Adding a lot of insult to mobile mounted verticals, is the typically low Q of the loading coils, and short lengths.
Fact is, few amateurs really understand just how inefficient an HF mobile antenna system is. It seems the only specific attributes which count are low SWR, short length, and ease of mounting. When they're lucky enough to work a few DX stations, then the worth of their choice is confirmed, and any discussion about efficiency is summarily dismissed.
Part of the article covers top loading. Top loading is a methodology which increases radiation resistance, hence efficiency, even if the ground plane is substandard; seemingly a ubiquitous vertical antenna shortcoming.
This article is also a must read especially if your urban bound! The conclusions at the end of Bob's article are well founded. Of specific importance are the following points. These conclusions support the thought that reducing ground losses, and maximizing radiation resistance are the two paramount objectives in achieving maximum performance from a base station vertical.
Or from an HF mobile antenna! Ground losses dominate the efficiency formula in any vertical installation, but it's of particular importance in a mobile environment. It is true there must be a solid connection for the currents to return to the source, but beyond bonding and a proper ground connection for the coax shield, there is little we can do. Digressing for a moment. Whether the encountered losses are serial or parallel, they appear as part of the resistive portion of the input impedance.
As such, they cannot be measured qualitatively broken down into their individual parts , but we certainly can measure them as a whole. All it takes is a relatively inexpensive antenna analyzer. To make things simple, we're combining the serial and parallel resistive losses together, and calling them ground loss. Further, the resistive portion of the input impedance also contains the radiation resistance; the only good loss an antenna has!
Here too, we can't separate it out from the other losses encountered. As a result, we have to be careful about making assumptions based solely on changes in the resistive component of the input impedance.
This point will become glaringly evident later on. As alluded to above, mounting the antenna higher up on the vehicle will reduce, but not eliminate, ground losses. The problem is, few amateurs are willing to drill holes, make custom brackets, and the other prerequisites necessary for minimizing ground losses.
Perhaps if they had a better understanding, they might think differently. Certainly the aforementioned articles are a very good place to start. Here's some additional food for thought. The calculated ground losses for an average vehicle vary from about 2 ohms on 10 meters, to about 10 ohms on 80 meters.
However, the real world losses can easily be double this amount. The factors which cause the loss have already been discussed. The only alternative we have, is to move the antenna as high as we can on the vehicle, albeit we have to contend with the localized conditions low trees, wires, etc. This said, we also have to keep as much metal mass under the antenna as possible, and we have to keep the antenna close to this mass. That is to say, mounting antennas atop long brackets is counterproductive.
The question remains, why is ground loss so important? If you've read the aforementioned articles, you'd already have an idea of the answer. From this author's empirical experience, the noted difference between low mounting trailer hitch, bumper, etc. But the truth is, you can't make a pat statement unless you consider all of the variables. In a mobile scenario, any specific calculation has to include the antenna's coil losses Q , the location of the coil base, center, etc.
Digressing again. As stated above, ground losses dominate the efficiency formula. However, in some cases coil losses become dominate. A case in point are the various, short and stubby, HF mobile antennas which have become all the rage; their coils have rather low Q ratings. If you design an HF mobile antenna carefully, you can achieve a coil Q averaging about as mounted in on the antenna. That's watts in, just 3 watts out! Combine this with an overall length of about 7 feet, and a ground loss of 12 ohms, and the radiation efficiency is just.
Few amateurs have a grasp of radiation resistance, but Bob Zavel's, W7SX, article does a good job explaining the factors involved. A length, incidentally, which is fixed by practicality in our mobile-in-motive environment. From that standpoint, an overall length of 13 feet is about the maximum, with just 10 feet being the mean average.
Based on this maximum length, and remembering our paraphrasing above; The efficiency of a fixed-height antenna can be optimized by orientating the maximum current point at the half way point height of the antenna, we're left with moving the current maxima up towards the top of the antenna. In his article, Bob discusses using supporting guys to top load a vertical antenna, which will indeed move the current maxima up.
Unfortunately, like adding radials, this isn't a luxury we have in a mobile environment. We do, however, have an alternative, albeit with a few of its own drawbacks. Enter the Cap Hat.
Properly placed, capacitive hats, sometimes referred to as top hats, increase the capacitance of that part of the antenna above the loading coil, thus moving the current maxima point towards the center of the antenna which in turn raises the overall radiation resistance. It does this without other adverse effects save one wind loading , but only if it is positioned correctly.
Digressing once again. Whatever capacitance any given cap hat adds, is the same no matter where it is placed. For example, when placed too close to the loading coil, the capacitance can have a detrimental effect on the coil's Q, and will indeed produce an increase in the measured input impedance.
For example, the left photo depicts a cap hat incorrectly installed. The input impedance and bandwidth will indeed increase in this example. However the changes are due to increased coil losses, and not by an increase in radiation resistance Rr. Therefore, the following assumes the cap hat is mounted at the very top of the antenna, and thus the noted increase in input impedance is a positive one, not a negative one.
I have owned, and used, four commercially-designed cap hats. Every one of them has had a major drawback, besides the acknowledged wind loading. Universally, they're too small to be truly effective; they're all designed to be mounted too close to the coil; their solid mounting hardware, albeit short, can have a negative effect on an antenna's structural integrity; and some of them are too expensive.
I wanted something better. Any design concept should have clearly stated objectives. In this case, there were criteria which needed to be satisfied. An increase in the radiation resistance was the prime goal, followed closely by wind loading, weight, and ruggedness. The reasoning will become apparent as we continue. Every commercially available cap hat, is designed to be supported atop a short, solid shaft. Since the prime goal was to increase radiation resistance as much as possible, the cap hat would have to be mounted at the very top of its support structure.
Using a solid shaft as a support would put the antenna in peril should the cap hat hit a low-hanging limb. This meant the support had to be flexible. Hence, the winding loading and physical weight become a critical factor.
The incorrectly-installed cap hat above left, consists of just spokes, with no outer rim, while the drawing at right shows one with a rim. In comparison, a cap hat with the peripheral connection, has an effective length nearly twice the cap hat's diameter. Here too, the maximum effect depends on where how high above the coil it is placed.
Put another way, adding the peripheral wire increases the cap hat's effectiveness by nearly 4 times, but only when properly mounted. There's a hidden factor at play, and that's the frequency of operation criterion. As mentioned above, a properly implemented cap hat, including its support structure, will increase the effective electrical length of an antenna.
If the effective length is too great, the maximum usable frequency criterion 17 meters in this case won't be met. As anyone can clearly see, it's a mixed bag of tricks, with clear limitations. One design was cone shaped, and another was shaped like a wire-framed flying saucer I live in Roswell, NM after all.
Antenna efficiency hf amateur. What Other Visitors Have Revealed About Their Antennas
Maximizing Efficiency in HF Mobile Antennas
But do you, my friend, have any idea what you could accomplish with the best antenna for ham radio systems ever?! We will investigate great antennas with the following product reviews to see which antenna is the best ham radio antenna for you. It comes along with a magnet that attaches itself to surfaces of metals for very easy mounting. Supports reading radio waves with different ranges of frequencies. It can support the standard radio frequencies and has support for very high-frequency VHF waves in the region of MHz and even ultra-high frequencies UHF between MHz, supporting radio waves of some very niche frequencies and detect radio waves from very far distances away.
Highlighted Features : Transmits radio waves in two frequency ranges for double band support. Comes packaged with a compatible cable with connector and magnet mount for metal surfaces. Power rating of 75 watts, a standard range for mid-range ham radio antennas. Check Price on Amazon. The Magnetic Mobile Antenna is another double-banded radio antenna for ham radio systems and following on from it, can transmit signals in two ranges; between MHz and MHz.
The extra range for extra detection is always desirable! The cable that is attached to the base of the antenna and with a length of 12 foot and pretty good build quality so it should provide decent length to mount the antenna from the radio at a distance. The antenna itself only has a length of 70 cm so if you are in need of a smaller antenna because of a lack of headroom for bigger sizes, this one is going to be right up your alley! Included coax cable is 12 foot, so 12 foot range with base station as center.
Magnetic base at the bottom of the stand for mounting on metal surfaces. The antenna itself is made of stainless steel and has a design that allows the antenna to be both waterproof and freeze proof so you can expect it to do its part even in adverse weather conditions. The Dual Brand Antenna uses the omnipresent PL connector so it should be okay with your particular radio system.
The dual band design of the Dual Brand Antenna allows two different ranges of frequencies to be transmitted so that the signals have a better chance of detection. Hope you appreciate the wordplay! Highlighted Features : Durability and weatherproofing for some extreme use cases. Dual Band support over two different frequency ranges. Very strong magnet base for the antenna for vehicle installation. Suitable for speedy vehicles too.
As the name suggests, the Eightwood dual-band antenna lets you access two ranges of frequencies; the very-high-frequency range is stated to be between and MHz and ultra-high frequency is rated to be between and MHz. The extension cable included with this antenna is quite long; If you want to place the antenna quite a bit of a distance away from the radio; e.
When in need, every foot counts! The magnetic base of the antenna sticks to metal surfaces well enough and given that it has a long enough cable, you will ideally want to mount this one around your house. Highlighted Features : Support for two bands over the same transmission. Use of the omnipresent and essential PL connector. Extension cable of Small but thick size suitable for taller vehicles.
The NA is a slightly different antenna for radios because it usually goes on top of radios and therefore, has a slightly different connector type.
To protect the SMA connector of the antenna, this particular model has an antenna cover, protecting both from elements of the environment and physical threats.
With a double banded range coverage of two bands with maximums of MHz, it is going to let you transmit over quite a significant range of frequencies. Has warranty coverage for about a year so if you come across any defects with the particular product, you can return it to get it exchanged for a new one. Coming at a meager 15 and a half inches, it is going to be quite a short antenna, making it ideal for use in walkie-talkies and portable radio systems, the first of its kind on this list!
Highlighted Features : Optimum size for use in walkie-talkies. Less than 16 inches! Warranty from the manufacturer with coverage over 12 months. Comes in a pack of two for greater boosting or precaution. Due to the small size, this particular radio is also super portable. It has a super slider coil that lets you tune your signal according to your needs. Comes along with extension rods if you want to be able to increase the size of the antenna mounted on your radio or any such device.
It could come in handy in certain cases for sure! For the power this is packing, you better get that mount fast! Highlighted Features : Small size of only 12 inches for super portability and use with smaller radios.
A slider coil to alter detection frequency with manual alteration for maximum efficiency. Has two extension rods to allow the option of mounting at a greater height. With dual-band support for both very high frequencies and ultra-high frequencies, the Nagoya NMO supports broadcasting radio waves at and MHz. There is no need to do any tuning in this particular antenna, as you might be able to tell due to the lack of tuning mechanisms.
The mount of the antenna uses an NMO connector, a slightly rarer connector no doubt but is also newer and better than many of the older mechanisms. With a solid brass mount and a Satin finish, it has a solid build and is not going to be breaking easily. Unless you drop it a long way or something of the sort, it should last you the bump or drop here and there.
For mounting on cars where you are likely to experience wind, this is one of the best ham radio antenna for cars. Highlighted Features : Auto tuning functionalities to save you from manually tuning to frequencies. Solid build quality for better durability for use with vehicles and rough weather.
With a power capacity rating up to watts, the Solarcon I-Max is going to be able to take quite the electric shock before giving way! Great product for roof mounting in this case! The antenna comes in three easy sections that are separated in the packaging but is quite straightforward to rearrange again in the correct way.
The antenna can amplify signals that you input into it up to 5. Coming in at 24 inches in size, it is going to be quite the amplifier! Reinforcing this antenna is a pretty robust mounting plate so it is going to absorb quite a bit of wind before giving way. Ham radios with meter bands will also benefit from the choice of material for this antenna!
Highlighted Features : Ability to weather lightning strikes with power up to watts. Ease of assembly and installation for very easy setting up on your roof. A decent gain of 5.
Attaches to a clamp instead of a mounting base so it will go better on concrete. A rather small antenna, the Survival Antenna is a very portable antenna and it will be very easy to just wrap in a circle and carry away with you, making it the ideal travel antenna. It might be the best ham radio mobile antenna you can get. The antenna itself is made of wire brass, reinforced with stainless steel fittings for certain components to add to the durability.
Small sized antennas definitely need extra protection. The build is also weather-sealed to a degree so expect it to survive to get a little wet. It is ready to use straight from the box so you do not have to waste any time in doing setup or anything. Plug and play is definitely the way! It is right up there with the best antenna for handheld ham radio systems period! Highlighted Features : Plug and play antenna so no need for any elaborate setting up process.
The small antenna body is well built with stainless steel and wire brass. Uses the SMA connector, a staple of walkie-talkie like devices. With several attachments in the body, the Hustler HF Multiband Antenna is going to give you coverage for up to 5 different bands of frequencies to transmit and receive in.
The antenna itself is 25 foot high, making it quite the ideal size to really bump up amplification. With the design, if you really want, you can also mount it on the ground without needing to use a separate mount.
You will just need to get a cable separately to connect it to the radio you are using. The connector used in the antenna is compatible with a number of different types of cables so you should have no trouble with that I imagine.
Handles electricity up to watts. Needless to say, this is a proper lightning rod of a beastly antenna! If you are looking for the best vertical antenna for ham radios then you should try this one without any hesitation. Highlighted Features : Coverage of 5 different bands in the same channel.
Endures electric currents with power up to watts. Needs a separate mount if mounting on solid surface. Tall height of 25 foot for boosted amplification. But honestly, you really need to understand the benefits of getting a proper ham radio antenna. Band Support: You need to know the number of bands an antenna can provide support for. My general recommendation for the ordinary user of ham radios would be to stick to dual-band antennas. Dual band antennas have coverage for a range of frequencies, one range in the very high range and the other in the ultra-high range.
UHF Support : As a general rule, higher frequencies in transmission usually translates in higher range coverage due to smaller wavelength. Gain : Another aspect to put some attention into is the degree of gain you want from your antenna.
High gain antennas can help you boost the strength of transmitted signals quite a bit and if you have trouble broadcasting your signal at good enough strength, such as a signal repeater, you are going to want to look at the rating of the signal gain.
It will depend on where your radio is at your home or garage or car and where exactly you want to mount the antenna.