Antenna Utilities
Three dimensional co-siting workstation for shared towers and rooftops, computing antenna to antenna isolation from real geometry and measured radiation patterns, and grading every figure against the validity bounds of the model that produced it.
Included in the 14-day Pro trial on every new account. No credit card.
Shared towers and commercial rooftops accumulate antennas from different operators, on different bands, pointing in different directions. Whether one system desensitises another depends on where each antenna sits, which way it faces, and how far it is tilted. Those are exactly the things a two dimensional height and offset model cannot express. ITU-R Report M.2244 section 8.2.1 measured 2.6 GHz panels at a fixed three metre horizontal separation. Rotating one antenna boresight from minus 45 to plus 45 degrees changed isolation by about twenty decibels, and four degrees of electrical downtilt on both moved it from 56 to 76 dB. At one fixed separation, orientation alone spanned roughly thirty decibels. Orientation dominates real isolation, so a model that knows only height and offset will treat two antennas on opposite tower faces as though they were stacked one above the other.
This tool places antennas in three dimensions on a structure you draw, resolves the real pairwise geometry including signed off boresight angles in both planes, and reports the isolation the path provides against the isolation each mechanism requires. Isolation is computed two ways for every pair: by the M.2244 closed form that most engineers know, and by pattern aware Friis using each antenna gain in the direction of the other. Both are always shown, along with which one the tool trusts for that pair and the reason. That matters more than it sounds, because the closed form is only valid in the far field of both antennas, and ordinary VHF and UHF spacings sit well inside the invalid region rather than outside it.
The site you are designing on is usually not empty, so licensed antennas import directly from the ACMA register, transmit and receive records alike. Point to point dishes are pointed at their real partner sites from the licensed link geometry rather than left facing north, and every imported antenna is held in place as the existing installation it is, so a new antenna is positioned around what is genuinely on the tower. Every figure carries its provenance: whether a pattern was measured or a generic envelope, whether a value came from a cited standard or a representative typical, and whether the spacing sits inside the bounds of the model behind the number. A check that could not be assessed is reported as not assessable and never as a pass.
Lattice tower, tower, monopole, guyed mast or rooftop pole, with height and base radius set so the taper follows automatically and mount radius changes with height the way real steel does. Antennas are dragged in the 3D view, snap onto the structure faces and follow the taper, and a standoff places them off the face with the resulting mount radius reported, because horizontal separation is the geometry the isolation models are most sensitive to.
The ITU-R Report M.2244 Annex 4 closed form, codified in SM.337-6, is computed alongside pattern aware Friis using each antenna gain toward the other. Both are always shown with the preferred model and its reason. Where the geometry is a slant rather than purely stacked or side by side, the M.2244 warning that its slant interpolation is not physically derived is carried as a note on the result rather than quietly ignored.
The vertical closed form holds beyond ten wavelengths of separation, which at 150 MHz is twenty metres, and the horizontal form beyond eight. Below about a fifth of a wavelength the vertical form returns an unphysical negative isolation. Ordinary rooftop spacings sit inside those bounds, so results are graded against the published limits, out of range pairs are counted in the status bar, and an unassessable check is never reported as a pass. A study that reads as clean because nothing could be assessed is the most dangerous output this tool could produce.
Transmitter broadband noise, receiver blocking, adjacent channel rejection, and harmonics and spurious emission are properties of one transmitter into one receiver and appear per pair. Receiver intermodulation, transmitter intermodulation and passive intermodulation are made by several transmitters together and are reported once per victim receiver. Receiver intermodulation follows ITU-R SM.1134-1 Annex 1 in full, and that Recommendation own worked example is carried as a regression test.
Two directional dishes are a fixed service pair and the land mobile susceptibility figures are the wrong model for them, so they are assessed by net filter discrimination instead: the ITU-R F.699 reference pattern for off boresight discrimination and the ETSI EN 302 217 emission and selectivity masks for off tune rejection, judged against an interference to noise criterion under the ACMA RALI FX 3 alternative criteria clause. Dishes in different bands report no interaction rather than a pass on an extrapolated mask.
Adjacent channel selectivity, blocking, spurious and intermodulation rejection are seeded from ETSI EN 300 086 for analogue PMR, EN 300 113 for digital PMR, EN 300 392-2 for TETRA, and DMR inheriting EN 300 113 as its own air interface standard directs. Each carries the clause it came from. Noise figure is specified in none of them, so it is asked for rather than assumed, and any field with no cited figure is left empty rather than filled with something plausible.
Antennas added from the component catalogue load their real measured radiation patterns in the background, which lifts their coupling figures from screening grade to measured. Antennas built from an archetype use a generic class envelope, which is a screening figure. The status bar states which basis the scene is on and the inspector tags each antenna, so a screening result is never mistaken for a measured one.
Licensed devices import from the ACMA register by site name or identifier, receive records included, because a co-siting study is transmitters into receivers and an import that kept only transmitters would report a clean study for a tower full of victims. Both importers make their gaps loud: transmit power backed out of EIRP is flagged as assumed, a device with no usable power arrives disabled, and representative receiver figures are tagged as typicals wherever a result rests on them.
Add an antenna from the library and it drops onto the best position for the frequencies and pattern it carries. From there you place it by clicking the plan view, taking the top ranked spot, or picking from a ranked table of genuinely distinct positions, and the search can be bound to the height band and compass arc the antenna could really occupy. Selecting a licensed antenna draws the same heat map for its fixed position, which answers whether it is already mounted in a poor spot.
Passive intermodulation depends on corrosion, contact pressure and dissimilar metals at joints that cannot be seen from a desk. The tool predicts where products land, flags the ones falling in a receiver, and points at inspection and testing. It will not return a level, because any level it returned would be invented. ITU-R SM.1446-0 defines and measures transmitter intermodulation but sets out no prediction formula, and that limit is respected rather than papered over.
Reach for the 3D Antenna Separation & Co-siting in any of the following situations.
Because orientation dominates real isolation. ITU-R Report M.2244 section 8.2.1 measured 2.6 GHz panels at a fixed three metre horizontal separation. Rotating one antenna boresight from minus 45 to plus 45 degrees changed isolation by about twenty decibels, and four degrees of electrical downtilt on both moved it from 56 to 76 dB. At one fixed separation, orientation alone spanned roughly thirty decibels. A height and offset model cannot represent any of that, and will treat two antennas on opposite faces of a tower at the same height as though they were stacked vertically.
It is excellent where it is valid, which is the far field of both antennas: beyond about ten wavelengths of vertical separation or eight horizontal. At 150 MHz ten wavelengths is twenty metres, so ordinary VHF and UHF rooftop spacings sit inside the invalid region, where the derivation has dropped terms that are no longer negligible and the error has no consistent sign. Rather than returning a confident number there, the tool grades results against the published bounds, counts out of range pairs, and prefers pattern aware Friis, which is what M.2244 itself recommends.
No. No Australian instrument and no tower company mandates a co-siting interference study, so this is engineering evidence for your own design decisions and for the site owner, not a compliance certificate. It is a desktop study: it predicts rather than measures, and it is neither an electromagnetic energy assessment nor a structural check. The value is knowing before you mount, against a lease that can require a system to be powered down at short notice once it is up.
Because they are a different discipline. Two directional dishes are a fixed service pair, and land mobile receiver susceptibility figures are the wrong model for them. They are assessed by net filter discrimination instead, using the ITU-R F.699 reference pattern for off boresight discrimination and the ETSI EN 302 217 masks for off tune rejection, against an interference to noise criterion under the ACMA RALI FX 3 alternative criteria clause. One site import therefore assesses both the land mobile and the fixed service antennas on the same tower.
No, and it will not pretend to. Passive intermodulation depends on corrosion, contact pressure and dissimilar metals at joints nobody can see from a desk. It cannot be calculated, only measured. The tool predicts where the products land, flags the ones falling in a receiver, and points you at inspection and testing. Returning a level would mean inventing one.
They are held in place. Imported antennas are locked from placement and drag, their mount fields are read only, and they are marked with a padlock, because they are the fixed reality a new antenna is fitted around. Selecting one still draws the placement heat map for its own position, which answers a real question: is it mounted where it should be? A licensed antenna sitting in the red is one in the wrong spot, though moving it is a licence variation rather than something the tool does for you.
It falls back to a generic class envelope, and the result is labelled screening grade rather than measured. The status bar states which basis the whole scene is on and the inspector tags each antenna individually. Screening is fine for ruling options in or out, but a mount should be committed on measured patterns, and the tool makes the difference visible rather than letting the two look alike.
Included in the 14-day Pro trial on every new account. No credit card.
