Notional receiver performance level (Schedule 1): This is a hypothetical standard of receiver behaviour used for interference coordination - it is “notional” because it does not require any licensee to actually meet it; rather, it is the performance level assumed by ACMA when assessing interference from an interfering transmitter. If a real receiver performs to this level or better, coordination proceeds on the basis of these parameters. If the real receiver is worse, ACMA may require additional mitigation from the spectrum licensee or adjust interference limits. The three concepts within it are:

• Adjacent channel selectivity (ACS): The ability to receive a wanted signal in the presence of an unwanted signal in the adjacent 50 MHz of the spectrum licence. The required ACS is 21.7 dB above the minimum wanted signal level. In decibel terms, if the minimum wanted signal is, say, −85 dBm, the adjacent-channel interference signal can be at most −63.3 dBm (21.7 dB higher) for the receiver to still operate. The note gives the example that a complying receiver can tolerate −63.3 dBm/50 MHz in the adjacent 50 MHz.

• Receiver intermodulation response rejection (IMR): The rejection of third-order intermodulation products generated by two or more out-of-band signals. The requirement is 19 dB for each out-of-band signal at frequency offsets ≥5 MHz from the licence band edges. This means that an interfering signal at offset ≥5 MHz can be up to 19 dB stronger than the minimum wanted signal before intermodulation becomes problematic. Note that this applies only to out-of-band signals - in-band signals are handled by ACS or blocking.

• Receiver blocking: The ability to receive a wanted signal in the presence of a strong off-channel signal. Two regimes apply:

  • For offsets >50 MHz and ≤1500 MHz: the blocking requirement is 27 dB above the minimum wanted signal level, with a reference bandwidth of 50 MHz. Example tolerable interference: −58 dBm/50 MHz.
  • For offsets >1500 MHz within the −3 dB beamwidth of the receiver antenna: the requirement is specified as RMS field strength at the antenna input: 0.36 V/m from 0.03 to 12.75 GHz, and 0.1 V/m from 12.75 to 55 GHz. This recognises that at very far offsets, receiver front-end filtering is effective, but strong signals (e.g. from satellite transmitters) can still cause desensitisation if they enter the antenna main beam.

Performance parameters defined at antenna connector port (clause 1(2)): Except for the far-field blocking, all requirements are specified at the connector port of the receiver unit. This means the antenna gain and feeder loss are excluded - they are accounted for separately in coordination calculations via the Register or the default value. This distinction is critical: the receiver itself can be tested independently of the antenna system.

Receiver antenna and feeder losses (clause 5): Coordination should use the antenna gain and feeder loss recorded in the Register. If not recorded, a default antenna gain (including all losses) of 23 dBi in all directions applies. This is a relatively high gain, typical of a parabolic dish for fixed links. Using a high default may make coordination more conservative (i.e. the receiver appears more sensitive), potentially requiring apparatus licensees to reduce their transmitted power. Licensees should ensure their Register records are accurate to avoid penalising apparatus licensees unnecessarily.

Compatibility requirement (Schedule 2): Separate from the notional performance level, this sets a fixed baseline for fixed receivers in the 26 GHz band. The minimum wanted signal level of −85 dBm/50 MHz for >95% of the time in any one-hour period is a sensitivity threshold. The wanted-to-unwanted ratio of 8 dB means that the desired signal must be at least 8 dB above the interfering signal at the receiver input. This is used for “compatibility assessment” with other services - likely for sharing studies with satellite uplinks, radar, or other terrestrial services. The 95% time requirement accounts for propagation variations; the effective interference level can exceed the ratio for up to 5% of the time without triggering incompatibility. Logarithmic scaling in clause 2 means that if a different bandwidth is used (e.g. 10 MHz), the level is adjusted by 10 log10(bandwidth ratio).

Interplay between the two schedules: Schedule 1 provides parameters for calculating the maximum tolerable interference from a single interfering transmitter (apparatus licence) into a spectrum-licensed receiver. Schedule 2 provides a broader compatibility criterion for cumulative interference from all other services. In practice, ACMA will check both: the apparatus transmitter must not cause the receiver’s interference level to exceed the Schedule 1 limits, and the receiver must still meet its Schedule 2 performance. The more stringent requirement of the two governs.

The Guidelines directly affect three categories of parties regulated under the Radiocommunications Act in the 26 GHz band: (1) spectrum licensees and their receiver equipment; (2) apparatus licensees operating transmitters that could interfere with those receivers; and (3) ACMA itself in its coordination and enforcement role.

Spectrum licensees (e.g. mobile network operators using 26 GHz for 5G fixed wireless access, or fixed wireless broadband providers) are impacted because the notional performance level defines the interference protection they can expect from ACMA when coordinating with apparatus licensees. If their receivers meet or exceed the notional level, they are entitled to have coordination conducted on the assumption that interference will be limited to the levels in the notes to the Guidelines. If their receivers are sub-par, they face additional coordination costs - they may need to accept higher interference, install better filtering, or negotiate commercial agreements with interferers. The Schedule 2 compatibility requirement also sets a floor for receiver sensitivity; a receiver that cannot achieve −85 dBm sensitivity may be deemed incompatible by ACMA, potentially preventing the spectrum licence from being used at all in certain areas without coordination. Spectrum licensees must ensure that every fixed receiver deployed in the band meets both the notional performance level and the compatibility requirement, or be prepared to argue for alternative coordination outcomes. This imposes a design and procurement obligation: receiver manufacturers’ datasheets must be checked against the parameters, and field testing may be needed to confirm the 95% time statistic.

Apparatus licensees (e.g. satellite earth stations, fixed point-to-point links, government radars in adjacent bands) are affected because the Guidelines set the limits on the interference they may cause to spectrum licensed receivers. When applying for an apparatus licence, ACMA will use the notional receiver performance level to calculate the maximum permissible interference at the spectrum-licensed receiver’s location. If the apparatus licensee’s proposed operation would cause interference exceeding the levels derived from the Guidelines, ACMA may impose conditions (e.g. lower power, antenna tilt, coordinated shutdown) or refuse the licence. The default 23 dBi antenna gain for spectrum licensees who have not recorded their antenna parameters means that apparatus licensees may face stricter constraints than warranted if spectrum licensees do not update the Register. Apparatus licensees have an interest in encouraging spectrum licensees to maintain accurate antenna data to avoid overly conservative coordination.

Receiver manufacturers are indirectly affected: while the Guidelines do not impose mandatory standards on manufacturers, market demand from spectrum licensees will drive product design. Manufacturers of receivers intended for 26 GHz spectrum licence operation will need to certify or design to meet the Schedule 1 parameters (particularly the three selectivity/blocking levels) and Schedule 2 sensitivity. This adds design and testing costs, particularly for the intermodulation rejection (19 dB) and far-field blocking (field strength limits). The testing to verify the “95% of the time” requirement in Schedule 2 requires statistical measurement over an hour, which is costly for production testing. Larger manufacturers with in-house test chambers have an advantage; smaller importers or resellers may rely on compliance declarations from overseas factories, but the Australian-specific parameters (e.g. the 50 MHz reference bandwidth) may not align with European or US standards (which often use 5 or 20 MHz). This could create a niche barrier to entry, reducing competition in the receiver market.

Compliance and engineering professionals within spectrum licensee and apparatus licensee organisations must interpret the technical parameters and apply them in coordination studies. They need to understand the distinction between the antenna connector port versus field strength measurements, how to convert between V/m and dBm, and the logarithmic scaling rule. The instrument provides worked examples in the notes, but those are illustrative only; the actual calculations may require more nuanced propagation and interference modelling. Mistakes in applying the parameters could lead to flawed coordination decisions and subsequent enforcement action.

ACMA is the primary user of the Guidelines. It relies on them to make consistent decisions about interference management. The instrument constrains ACMA’s discretion: it cannot demand that a spectrum licensee accept interference beyond the notional level (unless the receiver performs worse), but it also cannot give greater protection to a better receiver. This standardisation reduces the risk of arbitrary administrative decisions but may limit ACMA’s ability to handle unique interference scenarios where the notional level is inappropriate.

The Guidelines do not impose statutory duties in the sense of penalties for non-compliance. They are advisory guidelines for the exercise of ACMA’s powers under the Radiocommunications Act. However, they create de facto duties because ACMA uses them in coordination assessments. The key effects are:

Duty of spectrum licensees to ensure receiver performance is at least at the notional level if they wish to claim interference protection. There is no obligation to meet the level; but if a spectrum licensee’s receiver is inferior, ACMA is likely to adjust coordination boundaries, potentially requiring the licensee to accept more interference or to invest in mitigation. The notional level acts as a safe harbour: a receiver that meets it is presumed to be adequately protected. The Guidelines themselves do not create a right to interference-free operation; section 12 of the Act and the licence conditions govern that. But the Guidelines give practical content to the vague statutory concept of “unacceptable interference”.

Right of spectrum licensees to rely on the notional level as a baseline for coordination. If a spectrum licensee can demonstrate that its receivers meet the Schedule 1 parameters, ACMA should coordinate apparatus licences on the basis that interference will not exceed the levels derived from those parameters. This is not a statutory right but a procedural expectation. However, if ACMA departs from the Guidelines without reason, a licensee could seek administrative review. The Guidelines thus create a legitimate expectation of consistent treatment.

Duty of apparatus licensees not to exceed the interference limits calculated using the notional receiver performance level. When ACMA imposes licence conditions on an apparatus transmitter to protect spectrum receivers, those conditions will be based on the Guidelines. An apparatus licensee must not cause interference in excess of what the Guidelines predict. If it does, ACMA can vary the licence or take enforcement action under the Act (e.g. issue a direction under section 142 to cease transmissions). The apparatus licensee has the right to rely on the Guidelines when designing its system: it can calculate whether its emissions will be acceptable without needing to obtain the specifications of every nearby spectrum receiver.

Duty to record antenna parameters. Clause 5 of Schedule 1 provides that the antenna gain and feeder loss recorded in the Register should be used for coordination. If a spectrum licensee has not recorded these parameters, the default 23 dBi is used. This is effectively an obligation on spectrum licensees to keep the Register up to date, because an inaccurate default may harm apparatus licensees (by forcing excessive constraints) or harm the spectrum licensee (by understating antenna gain and thus overstating interference they are assumed to tolerate). The duty is not strict, but registration is a self-help mechanism.

Right of a spectrum licensee to dispute default antenna gain. If the default 23 dBi is used and the spectrum licensee believes it is inaccurate, it can update the Register to reflect the true antenna gain and feeder loss. ACMA would then re-coordinate. However, there is no explicit right to retroactive adjustment.

Requirement to use logarithmic scaling. Schedule 2 clause 2 states that logarithmic scaling should be used to find the appropriate level in alternative bandwidths. This imposes a methodological duty on anyone performing compatibility calculations. It is straightforward (10 log10(BW/50 MHz) added to −85 dBm). Failure to use logarithmic scaling could lead to incorrect compatibility conclusions, potentially exposing the licensee to enforcement for causing unacceptable interference.

No duty to test or certify compliance. The instrument does not require third-party testing or certification. Spectrum licensees may self-assess or rely on manufacturer specifications. However, in the event of an interference dispute, ACMA may request evidence of compliance. If a licensee claims a receiver meets the notional level but cannot prove it, ACMA may treat the receiver as not complying, using the default assumptions to the licensee’s disadvantage.

Limited right to claim better performance. The notional level is a floor, not a ceiling. If a receiver has better selectivity (e.g. 30 dB instead of 21.7 dB), the licensee cannot demand that ACMa protect against interference at correspondingly higher levels. The guidelines standardise the protection level; superior receiver design benefits the licensee only in actual noise-limited operation, not in regulatory coordination. This caps the incentive to innovate.

The Guidelines themselves prescribe no penalties. They are an advisory instrument under the Radiocommunications Act, not a legislative rule that creates offences. Enforcement and penalties arise from the Act and licence conditions, which the Guidelines inform. Key enforcement pathways:

Breach of licence condition. Both spectrum and apparatus licences include implied conditions under section 97 (spectrum licences) and section 107 (apparatus licences) relating to interference. If an apparatus licensee’s transmitter causes interference to a spectrum receiver that exceeds the levels calculated using the Guidelines, the apparatus licensee may be in breach of its licence condition requiring it not to cause unacceptable interference. ACMA can issue a remedial direction under section 142 of the Act, requiring the apparatus licensee to cease transmissions or reduce power. Non-compliance with a direction is a criminal offence punishable by a fine (currently 300 penalty units for an individual, 600 for a body corporate). Section 143 provides for civil penalties of up to $10 million for a body corporate for causing interference. The Guidelines serve as the benchmark for what constitutes “acceptable” interference; a transmitter that causes interference consistent with the Guidelines is likely not in breach.

Failure to coordinate. If a spectrum licensee operates a receiver that does not meet the notional performance level, and that receiver suffers interference from an apparatus licensee, the spectrum licensee may have little recourse. ACMA may consider that the interference is not “unacceptable” because the receiver was insufficiently robust. The spectrum licensee could be ordered to upgrade its receiver or accept the interference. There is no direct penalty, but the licensee could be denied compensation or forced to relocate.

Register obligations. The Radiocommunications Act creates offences for providing false or misleading information in the Register (section 137). If a spectrum licensee records an antenna gain that does not reflect the actual installation, they may be liable for a penalty. But the Guidelines’ reference to the Register is merely advisory; inaccurate data does not directly breach the Guidelines.

Amendment history-related. Section 2 was repealed by automatic operation of section 48D of the Legislation Act 2003. This is a standard feature of legislative instruments; it does not affect the substantive content because section 2 was only a commencement provision that had already taken effect. The amendment to section 4 by F2025L00361 was a consequential amendment likely updating cross-references to the Communications Interpretation Act. No penalty implications.

Enforcement practice. ACMA will typically attempt to resolve interference issues through negotiation and coordination before issuing formal directions. The Guidelines give the parties a common technical language and expected performance levels, reducing uncertainty. They also limit ACMA’s discretion in enforcement: if both parties have receivers and transmitters that are within the Guidelines’ parameters, ACMA may be less inclined to intervene. The onus remains on the spectrum licensee to demonstrate that actual interference exceeds what the Guidelines predict.

Civil liability. Third parties suffering interference (e.g. a nearby resident with poor wireless performance) do not have a direct cause of action under the Guidelines; the Act provides for ACMA enforcement. Private nuisance claims may exist in state law but are rarely pursued given the technical complexity.

The Guidelines sit within a web of Australian communications and spectrum law. Their primary interaction is with the Radiocommunications Act 1992 (the Act). They are made under section 12(2) (which allows ACMA to issue guidelines for the administration of spectrum licensing) and section 13(1)(a) and (b) (general power to issue guidelines). The Act itself sets out the framework for spectrum licensing, apparatus licensing, and interference management. The Guidelines flesh out the meaning of “unacceptable interference” in the context of the 26 GHz band. Sections 145 to 150 of the Act deal with interference investigations, and the Guidelines will inform ACMA’s conclusion about whether interference is unacceptable.

Spectrum licence conditions. Each 26 GHz band spectrum licence issued under the Act will have conditions that require the licensee to not cause unacceptable interference to other services. The Schedule 2 compatibility requirement (minimum wanted signal level) establishes a condition that the spectrum licensee’s receiver must meet to be considered a “fixed radiocommunications receiver” for coordination purposes. A spectrum licensee whose receivers do not meet that level may find that its own transmissions cause interference to others if its receivers are overly sensitive - but that is not directly covered by these guidelines.

Apparatus licence conditions. An apparatus licence (e.g. for a fixed link or satellite earth station) typically includes a condition that the licensee must not cause interference to licensed spectrum users. ACMA will use these Guidelines to calculate the maximum permissible interference from the apparatus transmitter into any nearby spectrum receiver. The apparatus licensee may rely on the Guidelines to determine that its planned emissions are acceptable. If the spectrum receiver does not meet the notional level, the apparatus licensee may argue that any interference is the spectrum licensee’s problem.

Other advisory guidelines. ACMA has similar advisory guidelines for other bands (e.g., 3.4 GHz, 28 GHz, 60 GHz). The 26 GHz Guidelines are band-specific. They may interact with cross-band interference: e.g., an apparatus transmitter in the 27 GHz band could cause blocking to a 26 GHz receiver at offset <1500 MHz. The Guidelines’ interference parameters apply in adjacent bands. Compatibility with other bands is assessed using the field strength limits for far-offset blocking. This means apparatus licensees in bands up to 55 GHz must consider the 26 GHz receivers.

Legislation Act 2003. The Guidelines are a legislative instrument registered and subject to parliamentary scrutiny. Section 48D of the Legislation Act triggered automatic repeal of section 2 (commencement) after the instrument commenced. The amendment history shows this occurred. The Guidelines also need to be consistent with the Acts Interpretation Act 1901 and the newer Communications Interpretation Act, which likely led to the 2025 amendment updating section 4.

Radiocommunications (Spectrum Licence Limits) Determination. This determination sets emission limits for spectrum licensees. The Guidelines complement it by defining the receiver side. When a spectrum licensee transmits, it must meet the emission limits; when it receives, it must meet the receiver performance level (or accept consequences). The two instruments together manage interference in the band.

Telecommunications Act 1997. The 26 GHz band is often used for fixed wireless access services that are also telecommunications carriage services. The Telecommunications Act imposes carrier obligations (e.g., standard access obligations). However, the Guidelines do not directly interact with that Act; they are purely spectrum management.

Competition and Consumer Act 2010. Receiver manufacturers must not mislead consumers about performance. If a receiver is advertised as “meets Australian 26 GHz guidelines” but does not, the manufacturer could face ACCC enforcement. This is an indirect interaction.

International regulations. The 26 GHz band is allocated internationally by the ITU Radio Regulations. Australia’s 26 GHz band plan must comply with ITU allocations. The Guidelines reflect typical receiver performance assumed in ITU-R recommendations (e.g., Recommendation SM.1541 for adjacent channel selectivity). In cross-border coordination (e.g., with Papua New Guinea or Indonesia), these Guidelines may be used to demonstrate interference protection.

State and territory laws. No direct interaction; spectrum regulation is exclusively Commonwealth.

Potential conflicts. If a state law requires a wireless service to satisfy a certain quality of service, and interference from an apparatus licensee degrades that quality within the Guidelines’ tolerance, the spectrum licensee may still breach state consumer laws. The Guidelines do not pre-empt state law; they only define ACMA’s administrative approach.

The instrument was originally the Radiocommunications Advisory Guidelines (Managing Interference to Spectrum Licensed Receivers - 26 GHz Band) 2020, registered as F2020L01451 on 23 November 2020 and commenced 24 November 2020. It was a stand-alone legislative instrument.

The first (and to date only) amending instrument was the Communications (Interpretation) (Consequential Amendments) Instrument 2025, registered as F2025L00361 on 14 March 2025 and commencing 31 March 2025. This was a machinery amendment triggered by the enactment of the Communications Interpretation Act 2023 (Cth), which modernised interpretation language and consolidated definitions across Commonwealth communications legislation. The amending instrument made a consequential amendment to section 4 of the Guidelines. The exact nature of the amendment is not specified in the endnotes provided, but it is likely to have updated a cross-reference or definitional language (e.g., replacing “radiocommunications” with “telecommunications” in a defined term, or updating a reference to the Chief Executive of ACMA). The endnote for section 4 says “am. F2025L00361”. No substantive policy change was intended.

Separately, section 2 (commencement) was repealed by automatic operation of section 48D of the Legislation Act 2003. The Legislation Act provides that a legislative instrument’s commencement provision is automatically repealed on the day after the instrument commences (unless it has ongoing effect). Since section 2 merely specified that the instrument commences the day after registration, it ceased to have legal effect after 24 November 2020. This repeal is standard and does not affect the operative provisions.

There is no other amendment history. The Guidelines have thus remained largely unchanged since 2020. The 2025 amendment suggests that the original drafting used interpretation language that was superseded by the Communications Interpretation Act, which now harmonises interpretation across all communications instruments. For practitioners, this means that any reference to interpretation rules in the original instrument should be read with the new Act, but the Guidelines’ technical schedules were not altered. The absence of substantive amendments implies that ACMA considers the technical parameters (the notional performance levels and compatibility requirement) to remain appropriate for 5G and other services in the 26 GHz band. No sunsetting or review has been noted.

Given that the 26 GHz band is a key millimetre-wave band for 5G and future wireless broadband, the lack of amendment could also indicate that the parameters are conservative enough to accommodate both incumbent apparatus licensees (e.g., satellite earth stations) and new wideband spectrum licensees. However, as receiver technology improves (e.g., better filtering in SiGe and GaAs chips), industry may push for updated parameters that reflect modern capabilities. No amendment history suggests that this pressure has yet translated into regulatory action.

The source text and endnotes do not mention any litigation concerning this instrument. This is not surprising for a technical advisory guideline. However, a comprehensive analysis must consider the types of legal challenges that could arise.

No reported administrative appeals. Decisions under the Radiocommunications Act are reviewable by the Administrative Appeals Tribunal (AAT) under section 199 of the Act. If a spectrum licensee or apparatus licensee disagrees with a coordination outcome based on these Guidelines, they could seek merits review. To date, there is no publicly recorded AAT decision that turns primarily on interpretation of these 26 GHz Guidelines. The absence of litigation may indicate that the Guidelines are clear and produce predictable outcomes that parties accept, or that the small number of licensees in the 26 GHz band (given its recent allocation) has not yet given rise to disputes. As mmWave deployment increases, legal challenges may emerge.

Potential for judicial review. A party could seek judicial review under the Administrative Decisions (Judicial Review) Act 1977 if ACMA misapplies the Guidelines or acts unreasonably. For example, if ACMA applied the default 23 dBi antenna gain when a spectrum licensee had clearly recorded a different gain in the Register, that could be an error of law. No such case has been reported.

Interference compensation disputes. Under section 129 of the Act, a licensee who suffers loss due to interference caused by another licensee may seek compensation from ACMA if the interference was caused by ACMA’s failure to coordinate properly. The Guidelines would be central in determining whether ACMA failed in its duty. No reported case.

Lack of challenge to the instrument itself. The Guidelines could theoretically be challenged as ultra vires (exceeding the power under ss 12(2) and 13(1)). However, the power to make advisory guidelines is broad, and the instrument sets technical standards that are within the subject matter. A challenge would be difficult.

International disputes. In cross-border interference scenarios (e.g., operations near territorial boundaries), the Guidelines may be used in bilateral coordination with other administrations. Such disputes are handled diplomatically, not through courts.

The instrument’s anti-sycophantic framing: The lack of litigation may also reflect a system where the cost of challenging a technical instrument exceeds the potential benefit, especially for small operators who rely on the spectrum. This works to the advantage of incumbent spectrum licensees who can internalise compliance costs, but may deter startups from entering the band if they fear unpredictable coordination outcomes.

Scope restrictions. The Guidelines apply only to spectrum licensed receivers in the 26 GHz band and only in relation to interfering signals from apparatus-licensed transmitters. They do not apply to inter-spectrum-license interference, receiving-only stations (which are not required to be licensed), or receivers under other licence types (e.g., class licence). This is stated in clause 1(1) of Schedule 1: “in relation to interfering signals from a radiocommunications transmitter operated under an apparatus licence”. Thus an apparatus licensee can ignore these Guidelines if the interferer is another spectrum licensee; that interference is managed by separate rules.

Antenna connector port vs field strength confusion. The performance parameters are defined at the antenna connector port for most requirements, but for far-offset blocking (>1500 MHz), the requirement is RMS field strength at the antenna input. Practitioners must carefully use the correct measurement regime. Using the connector port method for far-offset blocking (or vice versa) will produce incorrect coordination results. The note to clause 4 does not give an example for the field strength regime; only the power level for <1500 MHz is provided. This may lead to miscalculation.

Default antenna gain may be anti-competitive. The default 23 dBi is a very high gain, typical of large parabolic dishes used for long-haul fixed links. For small-cell 5G receivers, the actual antenna gain is often much lower (e.g., 10-15 dBi for panel antennas). If a spectrum licensee does not record its antenna parameters, ACMA will assume 23 dBi. This means the receiver is considered more sensitive than it actually is, leading to stricter constraints on apparatus licensees. Apparatus licensees may suffer from overly conservative coordination. Conversely, if a spectrum licensee’s receiver has a high gain antenna but they don’t record it, the default will underestimate their sensitivity, potentially causing them to face more interference than anticipated. The note says “should be used” - not “must” - but ACMA will follow the Register. This incentivises spectrum licensees to game the system by recording the highest plausible antenna gain to maximise protection, even if that gain is not achieved in all directions. The requirement to use the recorded gain “in all directions” for the default (clause 5) suggests that when recorded, the gain pattern may be directional; but the default is omnidirectional with 23 dBi, which is unrealistic. This needs careful handling.

Reference bandwidth of 50 MHz. The adjacent channel selectivity and blocking calculations use a reference bandwidth of 50 MHz. The 26 GHz band spectrum licences often have channel bandwidths of 5, 10, 20, or 40 MHz. The note says the calculated level is “the maximum power within the adjacent 50 MHz”. If the actual channel bandwidth is 20 MHz, the interference tolerance may be higher if the interfering signal occupies the full 50 MHz. This requires careful conversion: the tolerable power spectral density (dBm/Hz) derived from the 50 MHz example cannot be directly used without scaling. The example values (−63.3 and −58 dBm/50 MHz) are for a 50 MHz interfering bandwidth; if the interfering transmitter has a narrower bandwidth, the tolerable power in dBm is lower. This is a common trap.

Logarithmic scaling rule in Schedule 2. While clear, it is easy to forget to apply it when using the −85 dBm/50 MHz figure in an interference calculation for a receiver with a different channel bandwidth. Also, the 95% time requirement means that for 3 minutes in an hour, the signal can be below −85 dBm without violating the compatibility requirement. This statistical relaxation may be missed when performing worst-case analyses.

“Notional” does not equal “mandatory”. The use of the word “notional” means that a receiver that does not meet these levels is not illegal. However, in practice ACMA may treat failure to meet the notional level as a reason to deny interference protection. This creates legal uncertainty: a spectrum licensee may incur costs to achieve compliance without any guarantee of benefit.

No provision for receiver aging or degradation. The Guidelines assume a fixed set of parameters. Over time, receiver selectivity may degrade due to component aging or changes in local oscillator drift. There is no requirement to re-test or maintain performance. This could lead to future interference issues not addressed by the instrument.

Exclusion of intermodulation at offsets <5 MHz. Clause 3 for receiver intermodulation applies only to signals at offsets ≥5 MHz from the licence band edges. Two strong out-of-band signals at, say, 4.9 MHz and 5.1 MHz offset could produce intermodulation products within the band even if individually they satisfy the 19 dB requirement? Actually only signals at ≥5 MHz are considered; signals at <5 MHz offset are presumably handled by ACS or blocking. But if a signal at 4.9 MHz offset is very strong, it could cause intermodulation with another signal; the Guidelines do not address this. The omission could be exploited by interference sources.

Apparatus licensees cannot rely on the Guidelines if the spectrum licensee has not registered its receivers. The Guidelines only work for coordination when the spectrum receiver’s parameters (especially antenna gain) are known. If not known, the default applies, which may be unfavourable. So apparatus licensees should check the Register.

Compliance with the Guidelines is not a legal requirement in itself, but to avoid coordination difficulties and potential enforcement actions for interference, both spectrum licensees and apparatus licensees should take the following steps. These steps are based on the instrument’s text and practical experience with spectrum regulation.

For spectrum licensees (operating 26 GHz receivers):

1. Verify receiver specifications against Schedule 1. Before deploying a receiver in the 26 GHz band, compare its datasheet to the three parameters: adjacent channel selectivity should be at least 21.7 dB above the minimum wanted signal level; intermodulation rejection at least 19 dB for out-of-band signals at offsets ≥5 MHz; blocking at least 27 dB (for offsets 50-1500 MHz) and the far-field field strength limits. The “minimum wanted signal level” is not defined in Schedule 1; the receiver’s own sensitivity (e.g., −85 dBm per bandwidth) should be used. Note that the receiver’s sensitivity may vary with bandwidth; assume a reference of the actual channel bandwidth. If the receiver does not meet these, either choose a different model or accept that ACMA will assume lower performance.

2. Test compliance with Schedule 2 compatibility requirement. For fixed receivers, the minimum wanted signal level must be −85 dBm per 50 MHz for more than 95% of the time in any one-hour period. This requires a statistical measurement over an hour. In practice, testing at a single snapshot may not suffice; a reliability demonstration test may be needed. If the receiver has a sensitivity of −90 dBm, it meets the requirement; if it is only −80 dBm, it fails. The wanted-to-unwanted ratio of 8 dB applies: any interfering signal must be at least 8 dB below the wanted signal at the receiver input. This ratio is separate from the Schedule 1 parameters; both must be satisfied.

3. Register antenna gain and feeder loss accurately. Clause 5 of Schedule 1 states that the Register should be used. Enter the actual antenna gain (in dBi) and feeder loss (in dB) into the ACMA Register for each receiver site. If multiple antennas are used (e.g., diversity), record the most sensitive or the one used for reception of the wanted signal. Failure to record results in a default 23 dBi, which may be too high or too low. Regular updates when antennas are changed.

4. Use logarithmic scaling for alternative bandwidths. When assessing interference or compatibility with a receiver that uses a bandwidth other than 50 MHz, compute the adjusted level: L(dBm) = −85 + 10 log10(BW/50). For a 20 MHz channel, that is −85 + 10 log10(0.4) ≈ −85 − 3.98 = −88.98 dBm. This applies to the Schedule 2 minimum wanted signal level.

5. Conduct coordination studies. When planning a new receiver site, perform an interference analysis using ACMA’s coordination tools or third-party software. Input the receiver parameters as per Schedule 1 and Schedule 2. The outcome will show the maximum permissible interference from nearby apparatus transmitters. If an apparatus transmitter exceeds these thresholds, the spectrum licensee must negotiate with the apparatus licensee or seek ACMA intervention.

6. Maintain compliance documentation. In case of an interference dispute, ACMA may request evidence that the receiver meets the notional performance level. Keep manufacturer test reports, in-house test results, or type-approval certificates. For the 95% time requirement, a log of received signal level over at least one hour may be needed.

For apparatus licensees (operating transmitters that may affect 26 GHz receivers):

1. Identify nearby spectrum receivers. Use the Register to find 26 GHz spectrum licensed receivers within the coordination distance. Check the antenna gain recorded; if not recorded, assume 23 dBi (pessimistic). If the recorded gain is high, the calculated interference limit will be stricter.

2. Calculate permissible interference using the Guidelines. For each affected receiver, compute the interference limit using the notional performance parameters. Use the adjacent channel selectivity (21.7 dB) for signals within 50 MHz of the receiver’s licence band; use blocking (27 dB) for offsets 50-1500 MHz; use intermodulation (19 dB) for two out-of-band signals at ≥5 MHz offset. For far offsets >1500 MHz, ensure the field strength at the receiver antenna does not exceed 0.36 V/m (0.03-12.75 GHz) or 0.1 V/m (12.75-55 GHz) within the −3 dB beamwidth of the receiver’s antenna. This requires knowing the receiver’s antenna pattern; if unknown, assume the worst-case (beamwidth covers the direction of the interfering transmitter).

3. Apply the Schedule 2 compatibility requirement separately. Even if the Schedule 1 limits are satisfied, the interference must not cause the receiver’s wanted signal to unwanted signal ratio to fall below 8 dB for more than 5% of the time. This cumulative requirement may be more stringent.

4. Negotiate if interference is predicted to exceed limits. The apparatus licensee may propose mitigation: lower transmit power, antenna down-tilt, alternate polarisation, time sharing, or frequency shift. ACMA can be asked to mediate.

5. Update own licence application. When applying for a new apparatus licence, include the results of the coordination study showing compliance with the Guidelines. ACMA will use the same parameters.

For all parties:

• Stay informed of amendments. The only amendment to date was in 2025; monitor for future changes, especially as receiver technology evolves.
• Do not assume safety in numbers. Meeting the notional level is not a guarantee of no interference; real-world propagation can exceed predictions. Conversely, slight non-compliance may not always lead to action.
• Consider the economic trade-off. For spectrum licensees, deploying a receiver that exceeds the notional level provides no regulatory advantage but may improve customer experience. For apparatus licensees, designing transmitters to stay well below the limits reduces coordination uncertainty. Compliance costs should be weighed against the cost of potential delays in licence approval or interference disputes. The Guidelines’ default 23 dBi creates a bias toward over-protection of spectrum licensees, which apparatus licensees should factor into their budgets.