COMPACtenna   …   COMPACT antenna
SMALL antennas        NO tuning (of antenna structure)        HIGH Performance


Easy to Install        Easy to Use


COMPACtenna Science & Technology is designed for the Convenient use of UPPER Corners of Vehicle
COMPACtenna is LESS restrictive than most antennas which have only one optimum spot, being the center of the roof ONLY.
All COMPACtenna models have MULTIPLE optimum possible locations, the upper corners of the vehicle.
Some have found, depending on their vehicle construct and mount style they use,
that they also get good results from the corners of the hood, or trunk lid, etc.
But not always, so these locations are not officially among the recommended ‘corners’.
The COMPACtenna is designed very short, allowing most people
to use the UPPER corners of their vehicle.
YouTube – HamRadioConcepts on COMPACtenna model 2M-440 Performance & SWR:
COMPACtenna YouTube HamRadioConcepts model 2M-440 Performance & SWR
With a short antenna, the hot voltage point is quite close to the ground plane counterpoise with consequently low resistance.
The high inductance and capacitance of the COMPACtenna magnetic field resonator design
are balanced at the corners for proper overall impedance in a short antenna,
working in conjunction with the downward/sloping metal of the
vehicle at the corner locations having increased resistance effect.
And this geometric dimensional counterpoise also results in 
a substantially omnidirectional VHF/UHF pattern.


VHF/UHF 7.5″ & 9″ models with: 
CompacCounterpoise – Optimized Ground Plane Counterpoise Radial Kit


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Follow local building codes including NEC grounding/lightning/etc. and NFPA guidelines.
Follow applicable RF-Exposure Regulations.
Professional Installation is recommended.
Don’t touch any part of antenna structure, ground plane/counterpoise, mounting/support, feedline, grounding,
lightning arrestor components/systems nor any other part of installation and related parts/structures while transmitting.


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7.5″ & 9″ COMPACtenna models    Vehicle and Base Station Application

2M/220/440 (7.5″)    2M/440 (7.5″)    2M/440+(9″)    SCAN-III (9″)    LMR-I (9″)


COMPACtenna PHOTO Vehicle 2M-440+ & SCAN-III at Corners LOGO w Upward Rings FOR WEBSITE HEADER 4
One of the key things is that getting the antenna as close to the corner as appropriate improves SWR’s
(Particularly at VHF frequencies).
Often moving it just an inch closer to the corner, for example makes a big difference.
[Some use such as NMO L-bracket mounts with screws to optimize corner location installation.]
Vehicle Antenna Mount Types
Through-Hole mounts have been found to work optimally more consistently than many other types. This style of mount commonly provides good juxtaposition between center and shield lead connections to antenna and ground plane counterpoise, which is particularly important with VHF/UHF, and they don’t have the challenge of adequate capacitive coupling to ground plane counterpoise that some other style mounts can have, particularly at HF frequencies.
L-Bracket & Adjustable Bracket attached-to-vehicle-metal with screws type mounts are also favorites by many for similar reasons.
As can be seen by the formulas, etc. below, magnet mount capacitive coupling is often quite good at VHF/UHF and some HF frequencies.
Before drilling holes such as with thru-hole and bracket-with-screws type mounts,
it can be helpful to have a magnet mount available to first test the intended location area 
while stationary and clear of surrounding metal and get an approximate idea of SWR there.
(Capacitive coupling to counterpoise with a magnet mount works even on flat aluminum roofs.)


Magnet mount on corner of pickup truck cab:

COMPACtenna Photo 7in Antenna Magnet Mount on Truck Cab

Magnet Mounts
Capacitive Coupling Reactance
A magnet mount provides good coupling,
particularly at VHF/UHF, with little capacitive impedance,
and even with transmitting at HF down to ~7MHz (40 meters): 
COMPACtenna Installation - Formulas for Magnet Mount Capacitive Coupling BOTH PAGES
[Note that a magnet mount with a “thick” rubber bottom ‘boot’ will decrease capacitive coupling.]
For VHF/UHF, ‘flatter style’ magnet mounts often provide best SWR’s, e.g.,
COMPACtenna Installation NMO Magnet Mount - LAIRD BLACK small Center PIN
Examples of magnet mounts
With this magnet mount type, designed for up to microwave frequencies, leave the center pin/disk and inner dielectric in place:
NMO Magnet Mount at DX Engineering
NMO Magnet Mount at Ham Radio Outlet
A good magnet mount with no pin/disk adapter:
Users report success also with this smaller version magnet mount with COMPACtenna 7.5” & 9” models.
This magnet mount is only 2 3/8” diameter allowing placement at the corner where greater
diameter magnet mounts are not applicable due to racks, roof curvature, etc.:
YouTube – LCARA Demonstrating Excellent SWR with ‘Flat’ Style Magnet Mount near Upper Corner of Vehicle:
COMPACtenna LCARA YouTube Flat Magnet Mount - Brian and Chris Perry Screen Shot

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Thru-Hole NMO Mount:
COMPACtenna Installation NMO - Thru-Hole Mount

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L-Bracket Body Mount Upper Corner Hatchback with NMO:
COMPACtenna PHOTO L-Bracket NMO my vehicle REAR-SIDE VIEW - CROPPED                  COMPACtenna PHOTO L-Bracket NMO my vehicle SIDE VIEW - CROPPED
COMPACtenna PHOTO L-Bracket NMO my vehicle REAR VIEW Dual NMO - CROPPED
L-bracket on the upper back corners of the cab of pickup trucks,
even aluminum ones such as the newer Ford F-150:
COMPACtenna Installation NMO L-Bracket on Corner Pickup Truck Cab
COMPACtenna Installation NMO L-Bracket Coax PL-259

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Adjustable bracket mount option with screws into vehicle body metal:
COMPACtenna Installation - Adjustable Mount - Firestick 'CB' models with NMO hole mount option discussed
Above:  Firestik SS204 Door/Hatch Jamb Mount on Left; SS274 Hood/Trunk Channel Mount on Right
Below:  A couple NMO through-hole mounts to consider for adjustable mounts


COMPACtenna Installation - HUSTLER CHMA-P .375 in hole NMO mount for .5 in hole of Adjustable Mount
Hustler CHMA-P at Ham Radio Outlet


Many vehicles allow passage of small ~0.2″ diameter RG-58 coaxial cable as with the Hustler CHMA-P mount above,
but some vehicles have especially narrow gaps between the closed hatch/door.
The Diamond NMO mount below has 1/8″ diameter coaxial cable:
COMPACtenna Installation - Adjustable Mount - NMO Antenna Hole Mount with Cable - Diamond C213SNMO - Requires ONLY .375in. HOLE
Diamond C213SNMO Mount at DX Engineering
Diamond C213SNMO Mount at Ham Radio Outlet

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NMO Mobile Antenna Adjustable Lip Mounts
For truck rear doors, SUV and van rear doors, trunk lids, hood lips, etc.
COMPACtenna 2M-220-440 W0RS Mobile Installation:
COMPACtenna 2M-220-440 Photo W0RS Mobile Installation Photo 2 with SWR's

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COMPACtenna Science & Technology is designed for the Convenient use of Upper Corners of Vehicle.
Many users report success with 3rd Brake Light Antenna Mounts such as this one from :
COMPACtenna Installation 3rd BRAKE LIGHT Truck Antenna Mount - FORD F-150
COMPACtenna Installation 3rd BRAKE LIGHT Truck Antenna Mount

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COMPACtenna is LESS restrictive than most antennas which have only one optimum spot, being the center of the roof ONLY.
All COMPACtenna models have MULTIPLE optimum possible locations, the upper corners of the vehicle.
Some have found, depending on their vehicle construct and mount style they use,
that they also get good results from the corners of the hood, or trunk lid, etc.
COMPACtenna PHOTO Vehicle 2M-220-440 on Chevy Truck - TheDadNerd YouTube - Photo1  COMPACtenna PHOTO Vehicle 2M-220-440 on Chevy Truck - TheDadNerd YouTube - Photo2
W0EGR, TheDadNerd on YouTube describes his COMPACtenna hood-fender installation on his stunning 2022 Chevy Trail Boss


7.5″ and 9″ Models  –  Base Station Application

On COMPACtenna  CompacCounterpoise  Ground Plane Radial Base Station Adapter Kit:
COMPACtenna CompacCounterpoise Photo with SCAN-III



Optimizing Installation of small antennas …in ‘small spaces’

Here are some techniques that can help achieve the successes so many have.
Each situation is different.
Often the installation-to-operation is rather straightforward.
Some experimentation/optimizing can prove quite beneficial for your particular system; see below.
One of the most common problems in any radio-antenna system is a connection problem.
A magnet mount may not have good continuity (internal disconnect); some are reported to be more reliable.
Connectors and adapters can be bad.
Some PL-259’s do not mate well with SO-239’s including at the transmitter, receiver, amplifier, test equipment.                           
Check your system as needed.
Limiting the number of connections is a good policy:

COMPACtenna HF 20&46in Antennas Coaxial Jumper with SO-239 at one end Photo



COMPACtenna HF 20&46in Antennas Coaxial Jumper with SO-239 Barrel Adapter Photo

With other ‘small’ antenna technologies it is ‘standard’ that one needs to tune the antenna structure itself,
either manually or remotely, sometimes changing the structural tuning for each frequency change.
With COMPACtenna Science & Technology, there is desirably no tuning of the antenna itself.
Instead, the ‘structural tuning’ is only when necessary and accomplished essentially by changing the position
of the antenna/antenna+counterpoise system, such as moving the antenna somewhat on the vehicle to an even better SWR-matched position 
generally near a top corner, moving a VHF/UHF antenna on CompacCounterpoise in an attic where there is interaction with nearby metal structures.
This is typically needed only when substantial parasitic interaction is ‘near’/influencing the antenna/counterpoise structure. 
[See ‘Transmitter Protection’ near bottom of page.]
Receive performance can be very negatively affected in noisy RF environments
due to unintentional radiators
such as switching power supplies, computers,
radio receivers which often use an intermediate frequency which is detectable outside the radio,
motors, dimmers, and corona from electrical powerlines,
and intentional radiators 
such as wireless garage door openers, wireless microphones, RF universal remote control devices,
cordless telephones, wireless alarm systems, Wi-Fi transmitters, and Bluetooth radio devices.
Wi-Fi Routers are a common substantial problem.
These can all generate RF noise.
Especially in radios-receivers with lesser filtering/shielding.
Front end overload and intermodulation problems can occur.
Sometimes the RF ‘noise’ is seen on the radio’s signal strength meter, yet sometimes it isn’t seen nor heard!
But it may be there nonetheless, causing desensitization of the receiver with poor reception of desired stations!
Of benefit can be toroids/RF beads on wires, cables and power leads at computers and electronic equipment and switching
power supplies and lamps because they can act as transmitting antennas.
A toroid/RF ferrite beads on a power strip cord help reduce RF from connected switching power supplies getting to electrical
wires of your house that can act as substantial antennas.
Not only the switching power supply of the Wi-Fi router can cause RF noise, but
IS VERY EFFECTIVE; adding ferrite beads to the ethernet cable at the router can provide some additional noise reduction.
It is not uncommon to see a substantial noise level on the radio’s signal meter, both VHF/UHF and HF at various frequencies,
and for S-meter reading to drop to zero by simply applying the ferrite beads as above.


Having the   ANTENNA OUTSIDE   often substantially reduces RF noise in that much of it commonly originates from within the house.
But simply creating a separation can be productive.
Distancing of the antenna from the computer and electronics for best reception is often a matter of experimentation.
Try different places at different distances.
(One ‘rule of thumb’ is 15 feet or more away.)
In addition, switching power supplies used to power the HAM Radio
can be very detrimental to BOTH TRANSMIT AND RECEIVE. 
The RF ‘noise’ from these switching power supplies can understandably affect receive, 
but also create oscillations that affect things such as transmit audio,
and even SWR measurement and tuner circuits!
Some have better filtering, but many operators recommend
non-switching transformer types especially for HF/SW transceivers/receivers
and even for (especially non-FM such as SSB) VHF/UHF transceivers/receivers. 
RF ferrite beads/toroids on power leads at the power supply can be helpful.
RF from the antenna itself through the air with proximity to the radio/equipment
can cause similar problems.
Increasing distance from the antenna to the equipment can be very helpful, and decreases RF exposure.
Another consideration is that with any small HF antenna the concentrated RF electromagnetic field is close to the coaxial cable
lead and can get onto the outside of the shield of the coax which can give a path back to the radio/equipment resulting in similar problems.
Also, the desirable level of capacitive coupling of the metal counterpoise to earth varies with installations, as does
parasitic coupling to surrounding structures, and common mode currents can occur.
Quite helpful can be few loops of the coax as a choke at/near the antenna end of the coaxial lead,
a toroid core or Ferrite (split) beads at both the antenna end and the radio end of the coaxial lead.
Check results including SWR.
When (split) ferrite beads are used along a coaxial cable, often 5-10 or more are needed.
Garage Door Openers
Avoid proximity to automatic garage door openers;
activation can occur.
A good System Ground is important. 
Stray RF can be substantially reduced.
Along with using the same power circuit/outlet as appropriate for your station equipment,
ground loop problems such as noise in reception can be dramatically reduced by a good common ground.
A poor RF ground can result in weak signals due to ground wire losses or radiation pattern distortion.
RF feedback can cause such things as modulation distortion or even stop your radio from working.
such as   Power, Microphone, Speaker, Amplifier, Data, PC, and Accessory   Leads/Wires/Cables. 

Transmitter Protection:
Check SWR with an antenna analyzer if possible.
Modify your installation for improvement if needed.
Reduce power output as appropriate.
Use an external tuner if necessary; improvement is generally adequate for 7.5″ & 9″ models by mounting location/style change (see above).
COMPACtenna Installation SAFETY SHEET 8.24.21