Low-profile microstrip end-fire antennas based on metamaterial substrates
Bibliographic record
Abstract
The development of microstrip technology has introduced a range of revolutionary antenna designs that provide a low-cost, easily integrable antenna in a low-profile, planar form factor. Typical microstrip antennas have either a broadside or an omnidirectional radiation pattern. This study investigates the design of a low-profile end-fire microstrip antenna based on the use of metamaterial substrates. A 900 MHz dipole antenna is placed above two types of high impedance surfaces (HIS): a single-layer HIS and a double-layer HIS. The patches forming the HIS were designed to produce a radiation pattern with main lobes as close to 90° from normal as possible. Our simulation results show that a single-layer HIS design with thickness of 0.06λ₀ and length and width of 1.1λ₀ by 1.1λ₀ has a main lobe at 56° from normal and an efficiency of 28%. A double-layer HIS design with a thickness of 0.03λ₀, a length of 1.1λ₀, and a width of 2.15λ₀ produces a main lobe at 40° from normal with an efficiency of 50%. In order to produce a radiation pattern closer to end-fire, we propose a compact microstrip patch antenna that uses a negative permittivity substrate to achieve an end-fire radiation pattern. The antenna is designed to operate at X-band frequencies and has a footprint of 42 mm². Loading a narrow patch with a negative permittivity substrate introduces an effective inductance that resonates with the strong fringing capacitance of the patch. The electric field is vertically polarized and nearly uniform across the patch with negative permittivity ensuring a uniform phase distribution. This introduces nulls in the transverse direction that improve the directivity of the antenna. The negative permittivity substrate is implemented using a thin-wire medium with four vias spread across the patch. The fabricated antenna is matched using a quarter-wavelength transformer to 50 Ω at 10.8 GHz with a peak return loss of 30 dB and a peak directivity of 11.3 dBi. The operating frequency appears between two parallel resonances and has a 10-dB impedance bandwidth of 4%. The efficiency is simulated to be approximately 85%.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".