Loop antennas may be constructed in many forms including horizontal full wave loops in square, rectangle or triangle (delta) shapes. They can also be in the vertical plane and are most often in the same shapes with the delta being very popular as it has both vertical and horizontal polarization. The impedance at the loop resonant frequency is approximately 100 ohms but will very slightly on harmonics. Loops are “quiet” antennas compared to verticals and dipoles and are omni-directional. The also exhibit gain on harmonic bands. Once you try a loop antenna you will know why they are so popular with old timers but still a secret to newcomers. Shown below are some typical designs:
Full Wave Horizontal Loop Antenna (a.k.a Skyloop)
This antenna is horizontally polarized and should be mounted as high as possible but works well at low heights of 10-30 feet. They are quieter than a dipole or a vertical, have a broader bandwidth and will usually out perform a dipole antenna.To determine the approximate circumference in feet of a full wave loop antenna use the formula:
1005/Freq in Mhz = length in feet.
The feed point impedance of a full wave loop antenna is theoretically in the vicinity of 120 ohms and requires a 2:1 impedance transformer (for single band loops or a 4:1 balun to match on multiple bands) with 50 ohm line. You will also need a feed line choke or better yet, just get the Hybrid 4:1+1:1 in a single box.
Vertical Delta Loops
Vertical delta loops can be oriented several way but the most popular is to have the “pointy” end at the top (usually a single support) and the lower horizontal ends just out of reach of humans and animals. Best feed point is 1/4 wavelength (246/f(mhz)) from the top point down one side. Vertical delta loops use the same 2:1 baluns as the horizontal loops or 4:1 for multi-band operation.
Complete Antenna System including 9:1 Unun matching unit (100/500/1500 watts PEP Options) antenna wire (41'/71'/111'/155'/173'), and a snap on feed line choke. Pack and Go Antenna System. FREE Shipping in USA!
Some Models Available at Ham Radio Outlet
Need a high performance, multi-band, stealthy antenna system that is easy to setup and use? Get the Bullet, the antenna wire, insulator and feed line choke all in one convenient package (great for HOA restricted areas, camping and portable operations, etc.).
check EHAM for reviews on this popular antenna
One of the most popular antennas today is the end fed due to it ease of installation, portability and stealth in various installations. It can be a condo dweller’s only access to the world of ham radio or the best alternative for a backpacking SOTA (Summits on the Air) mountaintop expedition.
The antenna is simple to deploy, folds up easily for transport, and weighs under a pound, yet, with the 71 foot included wire, can work the 80-10 meter bands easily with the built in antenna tuner of most current day transceivers.
The key to the antennas success is the matching network interface between the long wire antenna and the coax feed line to the transceiver. Palomar Engineers employs a dual core matching system that offers wide bandwidth (1.8-61 MHz), 500 watt PEP rating, and a connection for a counterpoise if desired, and a SO-239 female coax connector for easy attachment of 50 ohm coax cable.
The antenna can be used as a sloper, “L” with a vertical section and a longer horizontal section, or as a random horizontal antenna between two trees or supports.
BULLET Matching Unit
Our antenna matching network is called the “Bullet” because of it shape and its effectiveness at taking down or contacting distant (DX) stations all over the world under the right conditions.
We sell the Bullet matching unit separately in 3 separate power ratings of 100/500 and 1500 watts PEP so you can add you own wire type and length (see table of suggested lengths below) or you can purchase a complete antenna system including wire, end insulator and support cord. The short 41 foot bullet antenna with a 100 watt rating is excellent for portable operations such as SOTA, NPOTA, JOTA, field day, etc.
For best results we recommend that the coax feed line be at least 1/4 wavelength on the lowest operating frequency since the coax braid is used as a counterpoise if you don’t use the external counterpoise terminal on the matching unit. We also recommend a feed line choke at the end of the coax feed line near the radio to prevent RFI common mode current from interfering with the radio. .
Two popular lengths to choose from:(80-40-30-20-17-15-12-10-6 meters – 71 feet of 14 gauge, insulated wire, dog bone end insulator)
(160-40-30-20-17-15-12-10-6 meters – 155 feet of 14 gauge, insulated wire, dog bone end insulator)
(AM Broadcast, 160-40-30-20-17-15-12-10-6 meters – 173 feet of 14 gauge, insulated wire, dog bone end insulator)
Note: Some bands require antenna tuner to minimize SWR
Three power levels to choose from: 100 watts PEP or 500 watts PEP or 1500 watts PEP (use for FT8 over 500 watts)
check EHAM for reviews on this popular antenna
Bullet Users Gallery and Testimonials
One of the most popular antennas today is the end fed due to it ease of installation, portability and stealth in various installations. It can be a condo dweller’s only access to the world of ham radio or the best alternative for a backpacking SOTA (Summits on the Air) mountaintop expedition.
The antenna is simple to deploy, folds up easily for transport, and weighs under a pound, yet, with the 71 foot included wire, can work the 80-10 meter bands easily with the built in antenna tuner of most current day transceivers.
The key to the antennas success is the matching network interface between the long wire antenna and the coax feed line to the transceiver. Palomar Engineers employs a dual core matching system that offers wide bandwidth (1.8-61 MHz), 500 watt PEP rating, and a connection for a counterpoise or ground if desired, and a SO-239 female coax connector for easy attachment of coax cable (50 or 75 ohm is ok).
The antenna can be used as a sloper, “L” with a vertical section and a longer horizontal section, or as a random horizontal antenna between two trees or supports.
BULLET Matching Unit
Our antenna matching network is called the “Bullet” because of it shape and its effectiveness at taking down or contacting distant (DX) stations all over the world under the right conditions.
We sell the Bullet matching unit separately so you can add you own wire type and length (see table of suggested lengths below) or you can purchase a complete antenna system including wire, end insulator and support cord. Available as the Bullet-9 (1.8-31 MHz) or 9LF (.2-30 MHz) for VLF use.
For best results we recommend that the coax feed line be at least 1/4 wavelength on the lowest operating frequency since the coax braid is used as a counterpoise if you don’t use the external counterpoise terminal on the matching unit. We also recommend a feed line choke at the end of the coax feed line near the radio to prevent RFI common mode current from interfering with the radio. .
Suggested wire lengths (measured from Bullet feed point):
|
Bands Covered (meters) |
Wire Length (feet) |
Choke distance to 9:1 (feet) |
|
| 40-6 |
41 |
16 feet |
|
|
|
|
||
|
80-6 |
71 - needs tuner on some bands |
42-50' (50' minimum coax required - not included) |
|
| 80-6 including 60 |
111 - needs tuner on some bands | 37' (50' minimum coax required - not included) | |
|
160-6 AM Band, 160-6 |
155 173 |
95' (100 feet minimum coax required - not included) 80' (100 feet minimum coax required - not included) |
Installation
For best results raise the Bullet matching unit as high as possible (use a tree or vertical support) and then extend the antenna wire horizontally or as an “L” (horizontal with vertical end drop).The antenna may also be deployed as a sloper with the Bullet matching unit at the top (best) with the wire sloping toward the ground (with the end high enough to avoid contact by humans or animals), or at the bottom of the sloper with the antenna wire rising to a higher point (see typical configurations on next page).
Additional Typical Antenna Configurations:
Antenna Length Modifications: For best results, chose a length from the table above as these lengths will form a non-resonant antenna for the amateur bands indicated.The antenna length should NOT be ¼, ½ wavelength on any frequency that you transmit as the impedance will be very high (or low) and will not transfer through the matching unit at a favorable impedance to your antenna tuner.The theory of the antenna length is to make the antenna non-resonant on any amateur band so that the impedance at the antenna side of the matching unit is in the range of 200-600 ohms and when divided by 9 will be in the range of your transceiver antenna tuner.
Any length of 50/75 ohm feed line ok (over 35 feet minimum) but longer feed lines over 50 feet may show reduced SWR on some bands due to soil conductivity, nearby objects, etc. Due to local ground conditions, antenna height and feed line length, SWR may vary and an antenna tuner may be required or some bands to bring SWR at end of feed line to acceptable levels.Use of one or more ¼ wavelength counterpoise(s) connected to the ground post of the matching unit may also improve antenna efficiency and reduce SWR on certain bands.The first counterpoise should be installed under the horizontal portion of the antenna for best results
Use a good quality 50/75 ohm cable adequate for the power level of your station.The Bullet-80 matching unit is rated for 500 watts PEP for SSB and 150 watts continuous carrier for AM, FM, digital modes, or 375 watts CW.If the matching unit becomes warm to the touch after transmitting at high power, reduce the power output or the internal matching unit may become damaged.
NOTE: The matching unit output is DC grounded to bleed off static electricity, however it is not RF grounded as the RF signal (at the coax connector) will see approximately 1/9 of the RF impedance on the antenna terminal of the matching unit (if the antenna impedance is between 200-600 ohms).
Bullet Antenna Configuration Notes
Testimonial:
Just wanted to drop a line and let you know how impressed I am with my BAS-71 kit that I picked up at my local HRO. I'm able to work every single HF band, 6-160m and most of them without my TS-590SG's internal tuner! (Amazed that I can now work 160m!) Simply configured as a sloper and I don't even have the recommended length of coax, I'm short by about 5-10ft. I will definitely recommend your products to my ham buddies! I will be buying another one of your end-feds for portable ops.
Testimonial: (From Ron, K2RP)
While I’m not a competitive contester, I’ve always enjoyed putting in a few hours during the CW Sweepstakes each November.This year family commitments limited my availability to Sunday afternoon.
However, it turned out that I was almost precluded from participating at all.Just before the contest, the balun on my trusty old G5RV bit the dust.
Fortunately, a few years ago, I acquired a Palomar Engineers “bullet” antenna for portable and Field Day use.Our informal FD group used it this year, along with several other antennas.We were able to raise it to about 45 feet, overlooking the Pacific Ocean, and it worked well.
I immediately thought of deploying this antenna as a temporary measure to see if I could participate somehow in Sweepstakes.I climbed out my second story window onto a patio cover, and hung the balun of the bullet antenna on a hook and connected the coax from the ailing G5RV.I tossed the 55 foot end fed wire off the patio cover, made a 90 degree turn around the avocado tree, and tied the end to the top of a 6 foot fence.The highest point of the antenna was perhaps 15 feet off the ground.Not the ideal setup for a major contest, especially during these poor propagation times, but it was the best I could do.
Without a counterpoise, my transceiver’s built in tuner loaded the antenna on all bands, 80 through 10, even though the manual specifies a longer wire for 80 meters.
The results were surprising:In less than 3 hours of “search-and-pounce” operating, I worked over 100 stations in 55 sections, most of them on the first call.Most were on 20 meters, with a number on 40, and even a few on 80 and 15.Remember, the maximum height of the antenna was only 15 feet!
While it’s unlikely that this setup could win any awards, especially in a busy, competitive session, it certainly saved Sweepstakes for me this year.
I plan to use the “bullet” on my occasional/portable operations.Its lightweight and compact size, ease of deployment, and non-critical configuration makes it a natural for this type of use.
In addition, it’s a solution for those in need of a “stealth” antenna for antenna restricted areas.The wire can be extended in a moment or two, and coiled up at the end of operations just as quickly.
Many of us, even those with modest stations, have a “backup” rig to get on the air quickly in case of unexpected equipment failure.I never gave much thought to a “backup” antenna, because my simple G5RV provided excellent reliability for many years of service.
One of Murphy’s Laws declares that equipment failures happen at the most inopportune times, and it certainly held true for me.I was lucky to have an easy to erect antenna when I needed it.Do you?
