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


Easy to Install        Easy to Use


Generally, best performance of a mobile antenna is achieved with location at the top of the vehicle.
Long antennas can be unsightly and often do not allow travel into garages, beneath underpasses,
and standard technology short antennas have significantly decreased performance and bandwidth.
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.
The short yet powerful COMPACtenna is designed for best results (SWR, Performance) at an upper corner of a vehicle.
COMPACtenna PHOTO L-Bracket NMO my vehicle REAR-SIDE VIEW - CROPPED             COMPACtenna PHOTO L-Bracket NMO my vehicle REAR VIEW Dual NMO - DEDICATED Radios, DEDICATED Antennas            COMPACtenna Installation NMO - Thru-Hole Mount 
COMPACtenna Photo 7in Antenna Magnet Mount on Truck Cab          COMPACtenna 2M-220-440 Photo W0RS Mobile Installation Photo 2 with SWR's       COMPACtenna Pickup Truck Image - Universal-Adaptable NMO Lip Mount Location - Resized smaller
COMPACtenna Science & Technology is designed for the Convenient use of UPPER Corners of Vehicle
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
COMPACtenna CompacCounterpoise PHOTO with 9in. Model - LABELLED Base Station 11.1.2022


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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″)


7.5″ and 9″ Models  –  Vehicle Application

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/Adaptable-Universal bracket mounts with screws to optimize corner location installation.]
METAL Ground Plane Vehicle Counterpoise
Apply antenna mount to metal with good (clean) ground connection
(magnet mount type provides capacitive coupling to ground)
Vehicle Antenna Mount Types
Through-Hole mounts with vehicles with metal roofs have been found to work optimally more consistently than many other types.
One benefit is that they don’t have the challenge of adequate connection/coupling to ground plane counterpoise that some mount types may.
L-Bracket & Adjustable-Universal Bracket attached-to-vehicle-metal with screws type mounts are also favorites by many for similar reasons.
Magnet Mounts:  As can be seen by the formulas, etc. below, magnet mount capacitive coupling is often quite good at VHF/UHF frequencies..
Lip Adjustable Mounts:  See below.
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: 
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. Laird GB8PI shown.
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:

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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 Installation NMO L-Bracket Coax PL-259 - SEAL UNDERSIDE TEXT
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 - DEDICATED Radios, DEDICATED Antennas


Adjustable-Universal bracket mount option
Can provide greater clearance and flexibility to achieve upper corner hatchback vehicle antenna mounting as above:
COMPACtenna Installation - Adjustable Mount - Firestik 'CB' DOOR JAM model with NMO hole mount option discussed
Below:  A couple NMO through-hole mounts to consider for adjustable mount above


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-Universal Lip Mounts
For SUV, Crossover and Van hatchback door upper corner
Also Pickup Truck upper rear of rear door
COMPACtenna 2M-220-440 W0RS Mobile Installation:
COMPACtenna 2M-220-440 Photo W0RS Mobile Installation Photo 2 with SWR's
COMPACtenna Pickup Truck Image - Universal-Adaptable NMO Lip Mount Location

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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


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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.
With other ‘small’ antenna technologies it is ‘standard’ that one needs to tune the antenna structure itself,
sometimes changing the structural tuning for each frequency change.
With COMPACtenna Science & Technology, there is desirably no tuning of the antenna itself.
Instead, antenna system ‘positional tuning’ is only when necessary and accomplished essentially by changing the location
of the antenna/antenna+counterpoise system.
Mobile: Moving the top-corner-of-vehicle-location antenna even closer to the corner (as appropriate) on the vehicle
to an even better SWR-matched position.
Base Station: Moving a VHF/UHF antenna on CompacCounterpoise in an attic when there is interaction with nearby metal structures.
This is typically needed only when substantial parasitic interaction is ‘near’/influencing the antenna/counterpoise structure. 
Receive performance can be very negatively affected in noisy RF environments
due to unintentional radiators
such as switching power supplies, computers, including as part of vehicles,
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 shielding and filtering including on the power line as well as on the RF input.
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!
Some radios are considerably more ‘immune’ to RF noise that can occur in vehicles even with the vehicle off !
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,
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.
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.
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.
Modify your installation for improvement if needed.
Reduce power output as appropriate.
COMPACtenna Installation SAFETY SHEET 8.24.21