Deletions:
Additions:
HF mobile has progressed a lot in the radio department over the years, but the antennas remain the challenge. A quarterwave on 10 meters is easy enough, and very efficient, but an 80 meter quarterwave antenna would be about 70 feet tall. So the HF mobile antenna must use inductance to resonate an antenna that is too short. On 20 meters and higher in frequency, most any mobile antenna will perform quite well. On 30 meters and lower in frequency the HF mobile antennas become increasingly inefficient and it takes a good design to minimize losses. 80 meters is difficult, and 160 meters is extremely tough. Large coils are required for good efficiency, and then the Q of the system increases so bandwidth becomes narrow. Choose between small, efficient, or bandwidth - but you only get to choose two. Antenna designs often choose reduced efficiency to obtain the desired bandwidth. To optimize efficiency within the confines of the mobile available height on the lower bands yields narrow bandwidth which compromises convenience and frequency agility unless a motor is used to readjust the antenna. So in effect the motor allows one to optimize convenience in spite of narrow bandwidth, and have good efficiency...
In the November 2007 issue QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from each and every one of them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This result may be correct, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup). Do not assume that tiny screwdriver is representative of the type. An average screwdriver (High Sierra, Tarheel) would perform considerably better, and a large screwdriver (Predator, Scorpion) would be in a different league altogether.
Types of HF Mobile Antennas
Using an automatic tuner together with a tall whip antenna has been done by many manufacturers from Icom to SGC. In this case you have a base loaded whip using relatively low Q coils (compared to large coils in the antenna) in the tuner. It works well on the higher frequencies, and not so well on the lower frequencies. It is very convenient, but don't expect good results on 80 meters...
Using an automatic tuner to gain some extra bandwidth on a narrow antenna works a bit better. The losses grow as the frequency departs from the resonant frequency of the antenna, but the transmitter will still run full power and you can QSY if you need to, as well as compensating for different environmental conditions changing the resonant frequency.
USE A SHORT HIGH VOLTAGE WIRE from the tuner to the whip. VERY high SWR exists on this line, and using coax there will both increase losses and add shunt capacitance which causes the tuner to add more L and increases losses even further. This is not important if the antenna is being operated near resonance, but the wire will work fine then, too. HIGH VOLTAGES ARE PRESENT when the antenna is off-resonance.
Helical Wound
The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a small diameter fiberglass tube lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 30 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils on the one tube and a shorting jumper to select the band. One of the Outbacker models disassembles in the middle, making it the most compact of this type.
One popular scheme is to mount several of these resonant antennas in parallel. The high impedance of the nonresonant antennas generally does not affect the tuning too much, so instant band changing without switching whips is possible. Some combinations of close in frequency bands may not work as well due to interactions in tuning.
Automatic Antenna Tuners
Deletions:
HF mobile has progressed a lot in the radio department over the years, but the antennas remain the challenge. A quarterwave on 10 meters is easy enough, and very efficient, but an 80 meter quarterwave antenna would be about 70 feet tall. So the HF mobile antenna must use inductance to resonate an antenna that is too short. On 20 meters and higher in frequency, most any mobile antenna will perform quite well. On 30 meters and lower in frequency the HF mobile antennas become increasingly inefficient and it takes a good design to minimize losses. 80 meters is difficult, and 160 meters is extremely tough. Large coils are required for good efficiency, and then the Q of the system increases so bandwidth becomes narrow. Choose between small, efficient, or bandwidth - but you only get to choose two. Antenna designs often choose reduced efficiency to obtain the desired bandwidth. To optimize all three yields narrow bandwidth which compromises convenience and frequency agility unless a motor is used to readjust the antenna, returning the convenience of frequency changes.
In the November 2007 issue QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from each and every one of them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This result may be correct, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup). Do not assume that tiny screwdriver is representative of the type. An average screwdriver (High Sierra, Tarheel) would perform considerably better, and a large screwdriver (Predator) would be in a different leage altogether.
Using an automatic tuner together with a tall whip antenna has been done by many manufacturers from Icom to SGC. In this case you have a base loaded whip using low Q coils in the antenna tuner. It works well on the higher frequencies, and not so well on the lower frequencies. It is very convenient, but don't expect good results on 80 meters...
Using an automatic tuner to gain some extra bandwidth on a narrow antenna works a bit better. The losses grow as the frequency departs from the resonant frequency of the antenna, but at least the transmitter will still run full power and you can QSY if you need to.
USE A SHORT HIGH VOLTAGE WIRE from the tuner the the whip. VERY high SWR exists on this line, and coax will both increase losses and add shunt capacitance which causes the tuner to add more L and increases losses even further. This is not important if the antenna is being operated near resonance, but the wire will work fine then, too. HIGH VOLTAGES ARE PRESENT when the antenna is off-resonance.
Helical Wound Antennas
The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the Outbacker models disassembles in the middle, making it the most compact of this type.
Additions:
Additions:
The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the Outbacker models disassembles in the middle, making it the most compact of this type.
Deletions:
- The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the Outbacker models disassembles in the middle, making it the most compact of this type.
Additions:
- The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the Outbacker models disassembles in the middle, making it the most compact of this type.
- Lakeview Hamstick
Deletions:
- The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the outbacker models disassembles in the middle, making it the most compact of this type.
- Lakeview Hamstick
Additions:
HF mobile has progressed a lot in the radio department over the years, but the antennas remain the challenge. A quarterwave on 10 meters is easy enough, and very efficient, but an 80 meter quarterwave antenna would be about 70 feet tall. So the HF mobile antenna must use inductance to resonate an antenna that is too short. On 20 meters and higher in frequency, most any mobile antenna will perform quite well. On 30 meters and lower in frequency the HF mobile antennas become increasingly inefficient and it takes a good design to minimize losses. 80 meters is difficult, and 160 meters is extremely tough. Large coils are required for good efficiency, and then the Q of the system increases so bandwidth becomes narrow. Choose between small, efficient, or bandwidth - but you only get to choose two. Antenna designs often choose reduced efficiency to obtain the desired bandwidth. To optimize all three yields narrow bandwidth which compromises convenience and frequency agility unless a motor is used to readjust the antenna, returning the convenience of frequency changes.
In the November 2007 issue QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from each and every one of them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This result may be correct, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup). Do not assume that tiny screwdriver is representative of the type. An average screwdriver (High Sierra, Tarheel) would perform considerably better, and a large screwdriver (Predator) would be in a different leage altogether.
Tuner and Whip
Using an automatic tuner together with a tall whip antenna has been done by many manufacturers from Icom to SGC. In this case you have a base loaded whip using low Q coils in the antenna tuner. It works well on the higher frequencies, and not so well on the lower frequencies. It is very convenient, but don't expect good results on 80 meters...
Using an automatic tuner to gain some extra bandwidth on a narrow antenna works a bit better. The losses grow as the frequency departs from the resonant frequency of the antenna, but at least the transmitter will still run full power and you can QSY if you need to.
USE A SHORT HIGH VOLTAGE WIRE from the tuner the the whip. VERY high SWR exists on this line, and coax will both increase losses and add shunt capacitance which causes the tuner to add more L and increases losses even further. This is not important if the antenna is being operated near resonance, but the wire will work fine then, too. HIGH VOLTAGES ARE PRESENT when the antenna is off-resonance.
Deletions:
On 20 meters and higher in frequency, most any mobile antenna will perform quite well. On 30 meters and lower in frequency the HF mobile antennas become increasingly inefficient and it takes a good design to minimize losses. 80 meters is difficult, and 160 meters is extremely tough.
In the November 2007 issue QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This is fine, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup).
Additions:
On 20 meters and higher in frequency, most any mobile antenna will perform quite well. On 30 meters and lower in frequency the HF mobile antennas become increasingly inefficient and it takes a good design to minimize losses. 80 meters is difficult, and 160 meters is extremely tough.
- The helically wound HF mobile antennas are extremely popular due to their low cost and reasonable performance. They consist of a coil wound on a fiberglass rod lower section and a whip top section. Tuning over a small range is accomplished by adjusting the top whip. They are very effective on 20 meters and up, and increasingly less effective on 40 meters and down, but they are small enough to work on a multi-magnet mount. Each antenna is tuned for a single band, except for the Outbacker types which have multiple coils and a shorting jumper to select the band. One of the outbacker models disassembles in the middle, making it the most compact of this type.
- Lakeview Hamstick
Center loaded HF mobile antennas have been shown to be easiest to make efficient. As the coil is moved up from the base toward the tip the overall efficiency of the system increases, but somewhere around the middle the amount of coil required begins to increase so quickly that the improvement is cancelled by the coil losses. There have been many types of center loaded mobile whips over the years, here are some that have survived and are still available new. The Bug Catcher types use large air coils and can be the most efficient, but the bandwidth becomes very narrow. The Resonator type use per-band coil and top whip sets and share the common lower mast. They offer more bandwidth, less performance and greater convenience.
Some would include these antennas in the screwdriver class, but they are not quite the same. The coil is non moving, and generally much larger diameter than the base section. The base houses the motor, so it is a moderately large diameter. The efficiency on lower frequencies of these large coils is excellent, and should surpass the screwdriver types. The coils are generally tapped on the inside, and can be completely weather sealed. The top whip support can be much stronger and is not dependent on the coil. The overall height of this antenna does not change as it does with a screwdriver. These designs can reach very high Q, which is good for performance and makes them narrow in bandwidth. However, since they can be remotely tuned this narrow bandwidth is not such a problem.
Deletions:
- Lakeview Hamstick
Some would include these antennas in the screwdriver class, but they are not quite the same. The coil is non moving, and generally much larger diameter than the base section. The base houses the motor, so it is a moderately large diameter. The efficiency on lower frequencies of these large coils is excellent, and should surpass the screwdriver types. The coils are generally tapped on the inside, and can be completely weather sealed. The top whip support can be much stronger and is not dependent on the coil. The overall height of this antenna does not change as it does with a screwdriver.
Additions:
November 2007 QST Review
In the November 2007 issue QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This is fine, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup).
Deletions:
Recent QST Review
Recently QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This is fine, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup).
Additions:
Recent QST Review
Recently QST Magazine published a review of mobile antennas. Reviews are always interesting, and something can be learned from them. This review included a compact screwdriver antenna as well as helical and center loaded antennas. The center loaded antennas tested best, followed by the helicals, and the screwdriver tested lowest in gain. This is fine, but there are several problems. The title of the article is "A comparison of HF Mobile Antenna Designs". They did not test "Designs", they tested sample articles. In the case of screwdriver type antennas the model they chose is not representative of the type. They tested a compact screwdriver that has small diameter wire wound with turns touching, a known low Q design. It is too bad they didn't choose something from the middle of the range of Screwdrivers, or even a couple of samples from different parts of the range. In small HF antennas, details really matter. Compact convenience is always a tradeoff, and the screwdriver they tested is the only antenna in their test that will fit in an 18" suitcase, complete with HF mobile equipment for a complete station including mag mount, tuner, radio, mic and cabling (I have such a setup).
Additions:
Deletions:
Additions:
Some would include these antennas in the screwdriver class, but they are not quite the same. The coil is non moving, and generally much larger diameter than the base section. The base houses the motor, so it is a moderately large diameter. The efficiency on lower frequencies of these large coils is excellent, and should surpass the screwdriver types. The coils are generally tapped on the inside, and can be completely weather sealed. The top whip support can be much stronger and is not dependent on the coil. The overall height of this antenna does not change as it does with a screwdriver.
Additions:
Deletions:
Additions:
Deletions:
Additions:
Screwdriver antennas feature a coil inside a metal tube. The coil rises out of the tube, supporting the base of the top whip. Contacts at the top of the tube carry the RF and make a center loaded antenna with a very large base diameter. A screwdriver motor turned a threaded rod in the first antennas, so begat the name. They can be very efficient if the coil is of good diameter, large conductors and wound with good spacing. Smaller versions are less efficient but more convenient, the usual tradeoff in antennas.
Deletions:
Screwdriver antennas feature a coil inside a metal tube. The coil rises out of the tube, carrying the top whip. Contacts at the top of the tube carry the RF and make a center loaded antenna with a very large base diameter. A screwdriver motor turned a threaded rod in the first antennas, so begat the name. They can be very efficient if the coil is of good diameter, large conductors and wound with good spacing. Smaller versions are less efficient but more convenient, the usual tradeoff in antennas.
No differences.
Additions:
Screwdriver antennas feature a coil inside a metal tube. The coil rises out of the tube, carrying the top whip. Contacts at the top of the tube carry the RF and make a center loaded antenna with a very large base diameter. A screwdriver motor turned a threaded rod in the first antennas, so begat the name. They can be very efficient if the coil is of good diameter, large conductors and wound with good spacing. Smaller versions are less efficient but more convenient, the usual tradeoff in antennas.
Hi-Q-Antennas∞ Charlie W6HIQ has up to 5" (maybe 6") coils
Deletions:
Additions:
Deletions:
- HiQ∞ Charlie W6HIQ has up to 5" coils
Additions:
- HiQ∞ Charlie W6HIQ has up to 5" coils
Deletions:
- HiQ∞ Charlie has up to 5" coils
Additions:
Deletions:
- Hamstick
- Clones
- The Original W6AAQ - Don Johnson developer of the screwdriver antenna (no website)
- High Sierra
- Tarheel
- Predator - BIG screwdriver
- Scorpion Antennas∞ New big Screwdrivers
- Yaesu ATAS
- GS Mfg∞
- TurboTuner
HF Mobile Antennas
work in progress
Helical Wound Antennas
Center Loaded
- Hustler Resonators
- Bug Catcher (large coil)
Screwdriver Motor Tuned
- The Original W6AAQ - Don Johnson developer of the screwdriver antenna (no website)
- High Sierra
- Tarheel
- Predator - BIG screwdriver
- Scorpion Antennas∞ New big Screwdrivers
- Yaesu ATAS
Motor Tuned Center Loaded
Motorized Antenna Auto-Tune Controllers